diff options
Diffstat (limited to 'kernel/locking/lockdep.c')
| -rw-r--r-- | kernel/locking/lockdep.c | 901 |
1 files changed, 695 insertions, 206 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index bdaf4829098c..4470680f0226 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -54,28 +54,60 @@ #include <linux/nmi.h> #include <linux/rcupdate.h> #include <linux/kprobes.h> +#include <linux/lockdep.h> +#include <linux/context_tracking.h> +#include <linux/console.h> #include <asm/sections.h> #include "lockdep_internals.h" -#define CREATE_TRACE_POINTS #include <trace/events/lock.h> #ifdef CONFIG_PROVE_LOCKING -int prove_locking = 1; +static int prove_locking = 1; module_param(prove_locking, int, 0644); #else #define prove_locking 0 #endif #ifdef CONFIG_LOCK_STAT -int lock_stat = 1; +static int lock_stat = 1; module_param(lock_stat, int, 0644); #else #define lock_stat 0 #endif +#ifdef CONFIG_SYSCTL +static const struct ctl_table kern_lockdep_table[] = { +#ifdef CONFIG_PROVE_LOCKING + { + .procname = "prove_locking", + .data = &prove_locking, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, +#endif /* CONFIG_PROVE_LOCKING */ +#ifdef CONFIG_LOCK_STAT + { + .procname = "lock_stat", + .data = &lock_stat, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, +#endif /* CONFIG_LOCK_STAT */ +}; + +static __init int kernel_lockdep_sysctls_init(void) +{ + register_sysctl_init("kernel", kern_lockdep_table); + return 0; +} +late_initcall(kernel_lockdep_sysctls_init); +#endif /* CONFIG_SYSCTL */ + DEFINE_PER_CPU(unsigned int, lockdep_recursion); EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion); @@ -125,10 +157,12 @@ static inline void lockdep_unlock(void) __this_cpu_dec(lockdep_recursion); } +#ifdef CONFIG_PROVE_LOCKING static inline bool lockdep_assert_locked(void) { return DEBUG_LOCKS_WARN_ON(__owner != current); } +#endif static struct task_struct *lockdep_selftest_task_struct; @@ -182,11 +216,9 @@ static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); static struct hlist_head lock_keys_hash[KEYHASH_SIZE]; unsigned long nr_lock_classes; unsigned long nr_zapped_classes; -#ifndef CONFIG_DEBUG_LOCKDEP -static -#endif +unsigned long max_lock_class_idx; struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; -static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS); +DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS); static inline struct lock_class *hlock_class(struct held_lock *hlock) { @@ -337,7 +369,7 @@ static inline void lock_release_holdtime(struct held_lock *hlock) * elements. These elements are linked together by the lock_entry member in * struct lock_class. */ -LIST_HEAD(all_lock_classes); +static LIST_HEAD(all_lock_classes); static LIST_HEAD(free_lock_classes); /** @@ -400,7 +432,7 @@ static inline u16 hlock_id(struct held_lock *hlock) return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS)); } -static inline unsigned int chain_hlock_class_idx(u16 hlock_id) +static inline __maybe_unused unsigned int chain_hlock_class_idx(u16 hlock_id) { return hlock_id & (MAX_LOCKDEP_KEYS - 1); } @@ -544,8 +576,10 @@ static struct lock_trace *save_trace(void) if (!debug_locks_off_graph_unlock()) return NULL; + nbcon_cpu_emergency_enter(); print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); dump_stack(); + nbcon_cpu_emergency_exit(); return NULL; } @@ -679,7 +713,7 @@ void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) usage[i] = '\0'; } -static void __print_lock_name(struct lock_class *class) +static void __print_lock_name(struct held_lock *hlock, struct lock_class *class) { char str[KSYM_NAME_LEN]; const char *name; @@ -694,18 +728,20 @@ static void __print_lock_name(struct lock_class *class) printk(KERN_CONT "#%d", class->name_version); if (class->subclass) printk(KERN_CONT "/%d", class->subclass); + if (hlock && class->print_fn) + class->print_fn(hlock->instance); } } -static void print_lock_name(struct lock_class *class) +static void print_lock_name(struct held_lock *hlock, struct lock_class *class) { char usage[LOCK_USAGE_CHARS]; get_usage_chars(class, usage); printk(KERN_CONT " ("); - __print_lock_name(class); - printk(KERN_CONT "){%s}-{%hd:%hd}", usage, + __print_lock_name(hlock, class); + printk(KERN_CONT "){%s}-{%d:%d}", usage, class->wait_type_outer ?: class->wait_type_inner, class->wait_type_inner); } @@ -742,7 +778,7 @@ static void print_lock(struct held_lock *hlock) } printk(KERN_CONT "%px", hlock->instance); - print_lock_name(lock); + print_lock_name(hlock, lock); printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip); } @@ -754,12 +790,12 @@ static void lockdep_print_held_locks(struct task_struct *p) printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p)); else printk("%d lock%s held by %s/%d:\n", depth, - depth > 1 ? "s" : "", p->comm, task_pid_nr(p)); + str_plural(depth), p->comm, task_pid_nr(p)); /* * It's not reliable to print a task's held locks if it's not sleeping * and it's not the current task. */ - if (p->state == TASK_RUNNING && p != current) + if (p != current && task_is_running(p)) return; for (i = 0; i < depth; i++) { printk(" #%d: ", i); @@ -789,20 +825,24 @@ static int very_verbose(struct lock_class *class) #ifdef __KERNEL__ static int static_obj(const void *obj) { - unsigned long start = (unsigned long) &_stext, - end = (unsigned long) &_end, - addr = (unsigned long) obj; + unsigned long addr = (unsigned long) obj; - if (arch_is_kernel_initmem_freed(addr)) - return 0; + if (is_kernel_core_data(addr)) + return 1; /* - * static variable? + * keys are allowed in the __ro_after_init section. */ - if ((addr >= start) && (addr < end)) + if (is_kernel_rodata(addr)) return 1; - if (arch_is_kernel_data(addr)) + /* + * in initdata section and used during bootup only? + * NOTE: On some platforms the initdata section is + * outside of the _stext ... _end range. + */ + if (system_state < SYSTEM_FREEING_INITMEM && + init_section_contains((void *)addr, 1)) return 1; /* @@ -842,7 +882,7 @@ static int count_matching_names(struct lock_class *new_class) } /* used from NMI context -- must be lockless */ -static __always_inline struct lock_class * +static noinstr struct lock_class * look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) { struct lockdep_subclass_key *key; @@ -850,12 +890,16 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) struct lock_class *class; if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { + instrumentation_begin(); debug_locks_off(); + nbcon_cpu_emergency_enter(); printk(KERN_ERR "BUG: looking up invalid subclass: %u\n", subclass); printk(KERN_ERR "turning off the locking correctness validator.\n"); dump_stack(); + nbcon_cpu_emergency_exit(); + instrumentation_end(); return NULL; } @@ -885,14 +929,16 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return NULL; - hlist_for_each_entry_rcu(class, hash_head, hash_entry) { + hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) { if (class->key == key) { /* * Huh! same key, different name? Did someone trample * on some memory? We're most confused. */ - WARN_ON_ONCE(class->name != lock->name && - lock->key != &__lockdep_no_validate__); + WARN_ONCE(class->name != lock->name && + lock->key != &__lockdep_no_validate__, + "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n", + lock->name, lock->key, class->name); return class; } } @@ -929,10 +975,13 @@ static bool assign_lock_key(struct lockdep_map *lock) else { /* Debug-check: all keys must be persistent! */ debug_locks_off(); + nbcon_cpu_emergency_enter(); pr_err("INFO: trying to register non-static key.\n"); - pr_err("the code is fine but needs lockdep annotation.\n"); + pr_err("The code is fine but needs lockdep annotation, or maybe\n"); + pr_err("you didn't initialize this object before use?\n"); pr_err("turning off the locking correctness validator.\n"); dump_stack(); + nbcon_cpu_emergency_exit(); return false; } @@ -1236,6 +1285,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) struct lockdep_subclass_key *key; struct hlist_head *hash_head; struct lock_class *class; + int idx; DEBUG_LOCKS_WARN_ON(!irqs_disabled()); @@ -1275,8 +1325,10 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) return NULL; } + nbcon_cpu_emergency_enter(); print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); dump_stack(); + nbcon_cpu_emergency_exit(); return NULL; } nr_lock_classes++; @@ -1290,6 +1342,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) class->name_version = count_matching_names(class); class->wait_type_inner = lock->wait_type_inner; class->wait_type_outer = lock->wait_type_outer; + class->lock_type = lock->lock_type; /* * We use RCU's safe list-add method to make * parallel walking of the hash-list safe: @@ -1300,15 +1353,20 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) * of classes. */ list_move_tail(&class->lock_entry, &all_lock_classes); + idx = class - lock_classes; + if (idx > max_lock_class_idx) + max_lock_class_idx = idx; if (verbose(class)) { graph_unlock(); + nbcon_cpu_emergency_enter(); printk("\nnew class %px: %s", class->key, class->name); if (class->name_version > 1) printk(KERN_CONT "#%d", class->name_version); printk(KERN_CONT "\n"); dump_stack(); + nbcon_cpu_emergency_exit(); if (!graph_lock()) { return NULL; @@ -1347,8 +1405,10 @@ static struct lock_list *alloc_list_entry(void) if (!debug_locks_off_graph_unlock()) return NULL; + nbcon_cpu_emergency_enter(); print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); dump_stack(); + nbcon_cpu_emergency_exit(); return NULL; } nr_list_entries++; @@ -1361,7 +1421,7 @@ static struct lock_list *alloc_list_entry(void) */ static int add_lock_to_list(struct lock_class *this, struct lock_class *links_to, struct list_head *head, - unsigned long ip, u16 distance, u8 dep, + u16 distance, u8 dep, const struct lock_trace *trace) { struct lock_list *entry; @@ -1391,7 +1451,7 @@ static int add_lock_to_list(struct lock_class *this, /* * For good efficiency of modular, we use power of 2 */ -#define MAX_CIRCULAR_QUEUE_SIZE 4096UL +#define MAX_CIRCULAR_QUEUE_SIZE (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS) #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) /* @@ -1671,6 +1731,7 @@ static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset) static enum bfs_result __bfs(struct lock_list *source_entry, void *data, bool (*match)(struct lock_list *entry, void *data), + bool (*skip)(struct lock_list *entry, void *data), struct lock_list **target_entry, int offset) { @@ -1731,7 +1792,12 @@ static enum bfs_result __bfs(struct lock_list *source_entry, /* * Step 3: we haven't visited this and there is a strong * dependency path to this, so check with @match. + * If @skip is provide and returns true, we skip this + * lock (and any path this lock is in). */ + if (skip && skip(lock, data)) + continue; + if (match(lock, data)) { *target_entry = lock; return BFS_RMATCH; @@ -1739,7 +1805,7 @@ static enum bfs_result __bfs(struct lock_list *source_entry, /* * Step 4: if not match, expand the path by adding the - * forward or backwards dependencis in the search + * forward or backwards dependencies in the search * */ first = true; @@ -1774,9 +1840,10 @@ static inline enum bfs_result __bfs_forwards(struct lock_list *src_entry, void *data, bool (*match)(struct lock_list *entry, void *data), + bool (*skip)(struct lock_list *entry, void *data), struct lock_list **target_entry) { - return __bfs(src_entry, data, match, target_entry, + return __bfs(src_entry, data, match, skip, target_entry, offsetof(struct lock_class, locks_after)); } @@ -1785,9 +1852,10 @@ static inline enum bfs_result __bfs_backwards(struct lock_list *src_entry, void *data, bool (*match)(struct lock_list *entry, void *data), + bool (*skip)(struct lock_list *entry, void *data), struct lock_list **target_entry) { - return __bfs(src_entry, data, match, target_entry, + return __bfs(src_entry, data, match, skip, target_entry, offsetof(struct lock_class, locks_before)); } @@ -1808,7 +1876,7 @@ print_circular_bug_entry(struct lock_list *target, int depth) if (debug_locks_silent) return; printk("\n-> #%u", depth); - print_lock_name(target->class); + print_lock_name(NULL, target->class); printk(KERN_CONT ":\n"); print_lock_trace(target->trace, 6); } @@ -1821,6 +1889,8 @@ print_circular_lock_scenario(struct held_lock *src, struct lock_class *source = hlock_class(src); struct lock_class *target = hlock_class(tgt); struct lock_class *parent = prt->class; + int src_read = src->read; + int tgt_read = tgt->read; /* * A direct locking problem where unsafe_class lock is taken @@ -1837,28 +1907,36 @@ print_circular_lock_scenario(struct held_lock *src, */ if (parent != source) { printk("Chain exists of:\n "); - __print_lock_name(source); + __print_lock_name(src, source); printk(KERN_CONT " --> "); - __print_lock_name(parent); + __print_lock_name(NULL, parent); printk(KERN_CONT " --> "); - __print_lock_name(target); + __print_lock_name(tgt, target); printk(KERN_CONT "\n\n"); } printk(" Possible unsafe locking scenario:\n\n"); printk(" CPU0 CPU1\n"); printk(" ---- ----\n"); - printk(" lock("); - __print_lock_name(target); + if (tgt_read != 0) + printk(" rlock("); + else + printk(" lock("); + __print_lock_name(tgt, target); printk(KERN_CONT ");\n"); printk(" lock("); - __print_lock_name(parent); + __print_lock_name(NULL, parent); printk(KERN_CONT ");\n"); printk(" lock("); - __print_lock_name(target); + __print_lock_name(tgt, target); printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(source); + if (src_read != 0) + printk(" rlock("); + else if (src->sync) + printk(" sync("); + else + printk(" lock("); + __print_lock_name(src, source); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); } @@ -1906,7 +1984,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth, * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the * dependency graph, as any strong path ..-> A -> B ->.. we can get with * having dependency A -> B, we could already get a equivalent path ..-> A -> - * .. -> B -> .. with A -> .. -> B. Therefore A -> B is reduntant. + * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. * * We need to make sure both the start and the end of A -> .. -> B is not * weaker than A -> B. For the start part, please see the comment in @@ -1976,6 +2054,8 @@ static noinline void print_circular_bug(struct lock_list *this, depth = get_lock_depth(target); + nbcon_cpu_emergency_enter(); + print_circular_bug_header(target, depth, check_src, check_tgt); parent = get_lock_parent(target); @@ -1994,6 +2074,8 @@ static noinline void print_circular_bug(struct lock_list *this, printk("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } static noinline void print_bfs_bug(int ret) @@ -2004,6 +2086,9 @@ static noinline void print_bfs_bug(int ret) /* * Breadth-first-search failed, graph got corrupted? */ + if (ret == BFS_EQUEUEFULL) + pr_warn("Increase LOCKDEP_CIRCULAR_QUEUE_BITS to avoid this warning:\n"); + WARN(1, "lockdep bfs error:%d\n", ret); } @@ -2018,7 +2103,7 @@ static unsigned long __lockdep_count_forward_deps(struct lock_list *this) unsigned long count = 0; struct lock_list *target_entry; - __bfs_forwards(this, (void *)&count, noop_count, &target_entry); + __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry); return count; } @@ -2043,7 +2128,7 @@ static unsigned long __lockdep_count_backward_deps(struct lock_list *this) unsigned long count = 0; struct lock_list *target_entry; - __bfs_backwards(this, (void *)&count, noop_count, &target_entry); + __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry); return count; } @@ -2071,11 +2156,12 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) static noinline enum bfs_result check_path(struct held_lock *target, struct lock_list *src_entry, bool (*match)(struct lock_list *entry, void *data), + bool (*skip)(struct lock_list *entry, void *data), struct lock_list **target_entry) { enum bfs_result ret; - ret = __bfs_forwards(src_entry, target, match, target_entry); + ret = __bfs_forwards(src_entry, target, match, skip, target_entry); if (unlikely(bfs_error(ret))) print_bfs_bug(ret); @@ -2083,6 +2169,8 @@ check_path(struct held_lock *target, struct lock_list *src_entry, return ret; } +static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *); + /* * Prove that the dependency graph starting at <src> can not * lead to <target>. If it can, there is a circle when adding @@ -2102,7 +2190,7 @@ check_noncircular(struct held_lock *src, struct held_lock *target, debug_atomic_inc(nr_cyclic_checks); - ret = check_path(target, &src_entry, hlock_conflict, &target_entry); + ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry); if (unlikely(ret == BFS_RMATCH)) { if (!*trace) { @@ -2114,52 +2202,15 @@ check_noncircular(struct held_lock *src, struct held_lock *target, *trace = save_trace(); } - print_circular_bug(&src_entry, target_entry, src, target); + if (src->class_idx == target->class_idx) + print_deadlock_bug(current, src, target); + else + print_circular_bug(&src_entry, target_entry, src, target); } return ret; } -#ifdef CONFIG_LOCKDEP_SMALL -/* - * Check that the dependency graph starting at <src> can lead to - * <target> or not. If it can, <src> -> <target> dependency is already - * in the graph. - * - * Return BFS_RMATCH if it does, or BFS_RMATCH if it does not, return BFS_E* if - * any error appears in the bfs search. - */ -static noinline enum bfs_result -check_redundant(struct held_lock *src, struct held_lock *target) -{ - enum bfs_result ret; - struct lock_list *target_entry; - struct lock_list src_entry; - - bfs_init_root(&src_entry, src); - /* - * Special setup for check_redundant(). - * - * To report redundant, we need to find a strong dependency path that - * is equal to or stronger than <src> -> <target>. So if <src> is E, - * we need to let __bfs() only search for a path starting at a -(E*)->, - * we achieve this by setting the initial node's ->only_xr to true in - * that case. And if <prev> is S, we set initial ->only_xr to false - * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant. - */ - src_entry.only_xr = src->read == 0; - - debug_atomic_inc(nr_redundant_checks); - - ret = check_path(target, &src_entry, hlock_equal, &target_entry); - - if (ret == BFS_RMATCH) - debug_atomic_inc(nr_redundant); - - return ret; -} -#endif - #ifdef CONFIG_TRACE_IRQFLAGS /* @@ -2230,6 +2281,49 @@ static inline bool usage_match(struct lock_list *entry, void *mask) return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask); } +static inline bool usage_skip(struct lock_list *entry, void *mask) +{ + if (entry->class->lock_type == LD_LOCK_NORMAL) + return false; + + /* + * Skip local_lock() for irq inversion detection. + * + * For !RT, local_lock() is not a real lock, so it won't carry any + * dependency. + * + * For RT, an irq inversion happens when we have lock A and B, and on + * some CPU we can have: + * + * lock(A); + * <interrupted> + * lock(B); + * + * where lock(B) cannot sleep, and we have a dependency B -> ... -> A. + * + * Now we prove local_lock() cannot exist in that dependency. First we + * have the observation for any lock chain L1 -> ... -> Ln, for any + * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise + * wait context check will complain. And since B is not a sleep lock, + * therefore B.inner_wait_type >= 2, and since the inner_wait_type of + * local_lock() is 3, which is greater than 2, therefore there is no + * way the local_lock() exists in the dependency B -> ... -> A. + * + * As a result, we will skip local_lock(), when we search for irq + * inversion bugs. + */ + if (entry->class->lock_type == LD_LOCK_PERCPU && + DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG)) + return false; + + /* + * Skip WAIT_OVERRIDE for irq inversion detection -- it's not actually + * a lock and only used to override the wait_type. + */ + + return true; +} + /* * Find a node in the forwards-direction dependency sub-graph starting * at @root->class that matches @bit. @@ -2245,7 +2339,7 @@ find_usage_forwards(struct lock_list *root, unsigned long usage_mask, debug_atomic_inc(nr_find_usage_forwards_checks); - result = __bfs_forwards(root, &usage_mask, usage_match, target_entry); + result = __bfs_forwards(root, &usage_mask, usage_match, usage_skip, target_entry); return result; } @@ -2262,7 +2356,7 @@ find_usage_backwards(struct lock_list *root, unsigned long usage_mask, debug_atomic_inc(nr_find_usage_backwards_checks); - result = __bfs_backwards(root, &usage_mask, usage_match, target_entry); + result = __bfs_backwards(root, &usage_mask, usage_match, usage_skip, target_entry); return result; } @@ -2272,7 +2366,7 @@ static void print_lock_class_header(struct lock_class *class, int depth) int bit; printk("%*s->", depth, ""); - print_lock_name(class); + print_lock_name(NULL, class); #ifdef CONFIG_DEBUG_LOCKDEP printk(KERN_CONT " ops: %lu", debug_class_ops_read(class)); #endif @@ -2294,7 +2388,56 @@ static void print_lock_class_header(struct lock_class *class, int depth) } /* - * printk the shortest lock dependencies from @start to @end in reverse order: + * Dependency path printing: + * + * After BFS we get a lock dependency path (linked via ->parent of lock_list), + * printing out each lock in the dependency path will help on understanding how + * the deadlock could happen. Here are some details about dependency path + * printing: + * + * 1) A lock_list can be either forwards or backwards for a lock dependency, + * for a lock dependency A -> B, there are two lock_lists: + * + * a) lock_list in the ->locks_after list of A, whose ->class is B and + * ->links_to is A. In this case, we can say the lock_list is + * "A -> B" (forwards case). + * + * b) lock_list in the ->locks_before list of B, whose ->class is A + * and ->links_to is B. In this case, we can say the lock_list is + * "B <- A" (bacwards case). + * + * The ->trace of both a) and b) point to the call trace where B was + * acquired with A held. + * + * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't + * represent a certain lock dependency, it only provides an initial entry + * for BFS. For example, BFS may introduce a "helper" lock_list whose + * ->class is A, as a result BFS will search all dependencies starting with + * A, e.g. A -> B or A -> C. + * + * The notation of a forwards helper lock_list is like "-> A", which means + * we should search the forwards dependencies starting with "A", e.g A -> B + * or A -> C. + * + * The notation of a bacwards helper lock_list is like "<- B", which means + * we should search the backwards dependencies ending with "B", e.g. + * B <- A or B <- C. + */ + +/* + * printk the shortest lock dependencies from @root to @leaf in reverse order. + * + * We have a lock dependency path as follow: + * + * @root @leaf + * | | + * V V + * ->parent ->parent + * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list | + * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln| + * + * , so it's natural that we start from @leaf and print every ->class and + * ->trace until we reach the @root. */ static void __used print_shortest_lock_dependencies(struct lock_list *leaf, @@ -2322,6 +2465,61 @@ print_shortest_lock_dependencies(struct lock_list *leaf, } while (entry && (depth >= 0)); } +/* + * printk the shortest lock dependencies from @leaf to @root. + * + * We have a lock dependency path (from a backwards search) as follow: + * + * @leaf @root + * | | + * V V + * ->parent ->parent + * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list | + * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln | + * + * , so when we iterate from @leaf to @root, we actually print the lock + * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order. + * + * Another thing to notice here is that ->class of L2 <- L1 is L1, while the + * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call + * trace of L1 in the dependency path, which is alright, because most of the + * time we can figure out where L1 is held from the call trace of L2. + */ +static void __used +print_shortest_lock_dependencies_backwards(struct lock_list *leaf, + struct lock_list *root) +{ + struct lock_list *entry = leaf; + const struct lock_trace *trace = NULL; + int depth; + + /*compute depth from generated tree by BFS*/ + depth = get_lock_depth(leaf); + + do { + print_lock_class_header(entry->class, depth); + if (trace) { + printk("%*s ... acquired at:\n", depth, ""); + print_lock_trace(trace, 2); + printk("\n"); + } + + /* + * Record the pointer to the trace for the next lock_list + * entry, see the comments for the function. + */ + trace = entry->trace; + + if (depth == 0 && (entry != root)) { + printk("lockdep:%s bad path found in chain graph\n", __func__); + break; + } + + entry = get_lock_parent(entry); + depth--; + } while (entry && (depth >= 0)); +} + static void print_irq_lock_scenario(struct lock_list *safe_entry, struct lock_list *unsafe_entry, @@ -2350,11 +2548,11 @@ print_irq_lock_scenario(struct lock_list *safe_entry, */ if (middle_class != unsafe_class) { printk("Chain exists of:\n "); - __print_lock_name(safe_class); + __print_lock_name(NULL, safe_class); printk(KERN_CONT " --> "); - __print_lock_name(middle_class); + __print_lock_name(NULL, middle_class); printk(KERN_CONT " --> "); - __print_lock_name(unsafe_class); + __print_lock_name(NULL, unsafe_class); printk(KERN_CONT "\n\n"); } @@ -2362,18 +2560,18 @@ print_irq_lock_scenario(struct lock_list *safe_entry, printk(" CPU0 CPU1\n"); printk(" ---- ----\n"); printk(" lock("); - __print_lock_name(unsafe_class); + __print_lock_name(NULL, unsafe_class); printk(KERN_CONT ");\n"); printk(" local_irq_disable();\n"); printk(" lock("); - __print_lock_name(safe_class); + __print_lock_name(NULL, safe_class); printk(KERN_CONT ");\n"); printk(" lock("); - __print_lock_name(middle_class); + __print_lock_name(NULL, middle_class); printk(KERN_CONT ");\n"); printk(" <Interrupt>\n"); printk(" lock("); - __print_lock_name(safe_class); + __print_lock_name(NULL, safe_class); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); } @@ -2393,6 +2591,8 @@ print_bad_irq_dependency(struct task_struct *curr, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("=====================================================\n"); pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", @@ -2410,20 +2610,20 @@ print_bad_irq_dependency(struct task_struct *curr, pr_warn("\nand this task is already holding:\n"); print_lock(prev); pr_warn("which would create a new lock dependency:\n"); - print_lock_name(hlock_class(prev)); + print_lock_name(prev, hlock_class(prev)); pr_cont(" ->"); - print_lock_name(hlock_class(next)); + print_lock_name(next, hlock_class(next)); pr_cont("\n"); pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", irqclass); - print_lock_name(backwards_entry->class); + print_lock_name(NULL, backwards_entry->class); pr_warn("\n... which became %s-irq-safe at:\n", irqclass); print_lock_trace(backwards_entry->class->usage_traces[bit1], 1); pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); - print_lock_name(forwards_entry->class); + print_lock_name(NULL, forwards_entry->class); pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); pr_warn("..."); @@ -2436,20 +2636,19 @@ print_bad_irq_dependency(struct task_struct *curr, lockdep_print_held_locks(curr); pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); - prev_root->trace = save_trace(); - if (!prev_root->trace) - return; - print_shortest_lock_dependencies(backwards_entry, prev_root); + print_shortest_lock_dependencies_backwards(backwards_entry, prev_root); pr_warn("\nthe dependencies between the lock to be acquired"); pr_warn(" and %s-irq-unsafe lock:\n", irqclass); next_root->trace = save_trace(); if (!next_root->trace) - return; + goto out; print_shortest_lock_dependencies(forwards_entry, next_root); pr_warn("\nstack backtrace:\n"); dump_stack(); +out: + nbcon_cpu_emergency_exit(); } static const char *state_names[] = { @@ -2627,7 +2826,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, */ bfs_init_rootb(&this, prev); - ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL); + ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL); if (bfs_error(ret)) { print_bfs_bug(ret); return 0; @@ -2657,8 +2856,18 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, * Step 3: we found a bad match! Now retrieve a lock from the backward * list whose usage mask matches the exclusive usage mask from the * lock found on the forward list. + * + * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering + * the follow case: + * + * When trying to add A -> B to the graph, we find that there is a + * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M, + * that B -> ... -> M. However M is **softirq-safe**, if we use exact + * invert bits of M's usage_mask, we will find another lock N that is + * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not + * cause a inversion deadlock. */ - backward_mask = original_mask(target_entry1->class->usage_mask); + backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL); ret = find_usage_backwards(&this, backward_mask, &target_entry); if (bfs_error(ret)) { @@ -2694,8 +2903,68 @@ static inline int check_irq_usage(struct task_struct *curr, { return 1; } + +static inline bool usage_skip(struct lock_list *entry, void *mask) +{ + return false; +} + #endif /* CONFIG_TRACE_IRQFLAGS */ +#ifdef CONFIG_LOCKDEP_SMALL +/* + * Check that the dependency graph starting at <src> can lead to + * <target> or not. If it can, <src> -> <target> dependency is already + * in the graph. + * + * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if + * any error appears in the bfs search. + */ +static noinline enum bfs_result +check_redundant(struct held_lock *src, struct held_lock *target) +{ + enum bfs_result ret; + struct lock_list *target_entry; + struct lock_list src_entry; + + bfs_init_root(&src_entry, src); + /* + * Special setup for check_redundant(). + * + * To report redundant, we need to find a strong dependency path that + * is equal to or stronger than <src> -> <target>. So if <src> is E, + * we need to let __bfs() only search for a path starting at a -(E*)->, + * we achieve this by setting the initial node's ->only_xr to true in + * that case. And if <prev> is S, we set initial ->only_xr to false + * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant. + */ + src_entry.only_xr = src->read == 0; + + debug_atomic_inc(nr_redundant_checks); + + /* + * Note: we skip local_lock() for redundant check, because as the + * comment in usage_skip(), A -> local_lock() -> B and A -> B are not + * the same. + */ + ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry); + + if (ret == BFS_RMATCH) + debug_atomic_inc(nr_redundant); + + return ret; +} + +#else + +static inline enum bfs_result +check_redundant(struct held_lock *src, struct held_lock *target) +{ + return BFS_RNOMATCH; +} + +#endif + static void inc_chains(int irq_context) { if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) @@ -2726,10 +2995,10 @@ print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) printk(" CPU0\n"); printk(" ----\n"); printk(" lock("); - __print_lock_name(prev); + __print_lock_name(prv, prev); printk(KERN_CONT ");\n"); printk(" lock("); - __print_lock_name(next); + __print_lock_name(nxt, next); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); printk(" May be due to missing lock nesting notation\n\n"); @@ -2739,9 +3008,13 @@ static void print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, struct held_lock *next) { + struct lock_class *class = hlock_class(prev); + if (!debug_locks_off_graph_unlock() || debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("============================================\n"); pr_warn("WARNING: possible recursive locking detected\n"); @@ -2753,12 +3026,19 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, pr_warn("\nbut task is already holding lock:\n"); print_lock(prev); + if (class->cmp_fn) { + pr_warn("and the lock comparison function returns %i:\n", + class->cmp_fn(prev->instance, next->instance)); + } + pr_warn("\nother info that might help us debug this:\n"); print_deadlock_scenario(next, prev); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } /* @@ -2774,6 +3054,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, static int check_deadlock(struct task_struct *curr, struct held_lock *next) { + struct lock_class *class; struct held_lock *prev; struct held_lock *nest = NULL; int i; @@ -2794,6 +3075,12 @@ check_deadlock(struct task_struct *curr, struct held_lock *next) if ((next->read == 2) && prev->read) continue; + class = hlock_class(prev); + + if (class->cmp_fn && + class->cmp_fn(prev->instance, next->instance) < 0) + continue; + /* * We're holding the nest_lock, which serializes this lock's * nesting behaviour. @@ -2855,6 +3142,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, return 2; } + if (prev->class_idx == next->class_idx) { + struct lock_class *class = hlock_class(prev); + + if (class->cmp_fn && + class->cmp_fn(prev->instance, next->instance) < 0) + return 2; + } + /* * Prove that the new <prev> -> <next> dependency would not * create a circular dependency in the graph. (We do this by @@ -2916,7 +3211,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, } } -#ifdef CONFIG_LOCKDEP_SMALL /* * Is the <prev> -> <next> link redundant? */ @@ -2925,7 +3219,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, return 0; else if (ret == BFS_RMATCH) return 2; -#endif if (!*trace) { *trace = save_trace(); @@ -2938,19 +3231,15 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, * to the previous lock's dependency list: */ ret = add_lock_to_list(hlock_class(next), hlock_class(prev), - &hlock_class(prev)->locks_after, - next->acquire_ip, distance, - calc_dep(prev, next), - *trace); + &hlock_class(prev)->locks_after, distance, + calc_dep(prev, next), *trace); if (!ret) return 0; ret = add_lock_to_list(hlock_class(prev), hlock_class(next), - &hlock_class(next)->locks_before, - next->acquire_ip, distance, - calc_depb(prev, next), - *trace); + &hlock_class(next)->locks_before, distance, + calc_depb(prev, next), *trace); if (!ret) return 0; @@ -3237,7 +3526,8 @@ static int alloc_chain_hlocks(int req) size = chain_block_size(curr); if (likely(size >= req)) { del_chain_block(0, size, chain_block_next(curr)); - add_chain_block(curr + req, size - req); + if (size > req) + add_chain_block(curr + req, size - req); return curr; } } @@ -3269,7 +3559,7 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) u16 chain_hlock = chain_hlocks[chain->base + i]; unsigned int class_idx = chain_hlock_class_idx(chain_hlock); - return lock_classes + class_idx - 1; + return lock_classes + class_idx; } /* @@ -3337,7 +3627,7 @@ static void print_chain_keys_chain(struct lock_chain *chain) hlock_id = chain_hlocks[chain->base + i]; chain_key = print_chain_key_iteration(hlock_id, chain_key); - print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1); + print_lock_name(NULL, lock_classes + chain_hlock_class_idx(hlock_id)); printk("\n"); } } @@ -3346,6 +3636,8 @@ static void print_collision(struct task_struct *curr, struct held_lock *hlock_next, struct lock_chain *chain) { + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("============================\n"); pr_warn("WARNING: chain_key collision\n"); @@ -3362,6 +3654,8 @@ static void print_collision(struct task_struct *curr, pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } #endif @@ -3452,8 +3746,10 @@ static inline int add_chain_cache(struct task_struct *curr, if (!debug_locks_off_graph_unlock()) return 0; + nbcon_cpu_emergency_enter(); print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); dump_stack(); + nbcon_cpu_emergency_exit(); return 0; } chain->chain_key = chain_key; @@ -3470,8 +3766,10 @@ static inline int add_chain_cache(struct task_struct *curr, if (!debug_locks_off_graph_unlock()) return 0; + nbcon_cpu_emergency_enter(); print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); dump_stack(); + nbcon_cpu_emergency_exit(); return 0; } @@ -3694,11 +3992,11 @@ static void print_usage_bug_scenario(struct held_lock *lock) printk(" CPU0\n"); printk(" ----\n"); printk(" lock("); - __print_lock_name(class); + __print_lock_name(lock, class); printk(KERN_CONT ");\n"); printk(" <Interrupt>\n"); printk(" lock("); - __print_lock_name(class); + __print_lock_name(lock, class); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); } @@ -3707,9 +4005,11 @@ static void print_usage_bug(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) { - if (!debug_locks_off_graph_unlock() || debug_locks_silent) + if (!debug_locks_off() || debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("================================\n"); pr_warn("WARNING: inconsistent lock state\n"); @@ -3738,6 +4038,8 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this, pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } /* @@ -3748,6 +4050,7 @@ valid_state(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) { if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) { + graph_unlock(); print_usage_bug(curr, this, bad_bit, new_bit); return 0; } @@ -3771,6 +4074,8 @@ print_irq_inversion_bug(struct task_struct *curr, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("========================================================\n"); pr_warn("WARNING: possible irq lock inversion dependency detected\n"); @@ -3783,7 +4088,7 @@ print_irq_inversion_bug(struct task_struct *curr, pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); else pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); - print_lock_name(other->class); + print_lock_name(NULL, other->class); pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); pr_warn("\nother info that might help us debug this:\n"); @@ -3811,11 +4116,13 @@ print_irq_inversion_bug(struct task_struct *curr, pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); root->trace = save_trace(); if (!root->trace) - return; + goto out; print_shortest_lock_dependencies(other, root); pr_warn("\nstack backtrace:\n"); dump_stack(); +out: + nbcon_cpu_emergency_exit(); } /* @@ -3892,6 +4199,8 @@ void print_irqtrace_events(struct task_struct *curr) { const struct irqtrace_events *trace = &curr->irqtrace; + nbcon_cpu_emergency_enter(); + printk("irq event stamp: %u\n", trace->irq_events); printk("hardirqs last enabled at (%u): [<%px>] %pS\n", trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip, @@ -3905,6 +4214,8 @@ void print_irqtrace_events(struct task_struct *curr) printk("softirqs last disabled at (%u): [<%px>] %pS\n", trace->softirq_disable_event, (void *)trace->softirq_disable_ip, (void *)trace->softirq_disable_ip); + + nbcon_cpu_emergency_exit(); } static int HARDIRQ_verbose(struct lock_class *class) @@ -4040,14 +4351,13 @@ static void __trace_hardirqs_on_caller(void) /** * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts - * @ip: Caller address * * Invoked before a possible transition to RCU idle from exit to user or * guest mode. This ensures that all RCU operations are done before RCU * stops watching. After the RCU transition lockdep_hardirqs_on() has to be * invoked to set the final state. */ -void lockdep_hardirqs_on_prepare(unsigned long ip) +void lockdep_hardirqs_on_prepare(void) { if (unlikely(!debug_locks)) return; @@ -4278,6 +4588,30 @@ void lockdep_softirqs_off(unsigned long ip) debug_atomic_inc(redundant_softirqs_off); } +/** + * lockdep_cleanup_dead_cpu - Ensure CPU lockdep state is cleanly stopped + * + * @cpu: index of offlined CPU + * @idle: task pointer for offlined CPU's idle thread + * + * Invoked after the CPU is dead. Ensures that the tracing infrastructure + * is left in a suitable state for the CPU to be subsequently brought + * online again. + */ +void lockdep_cleanup_dead_cpu(unsigned int cpu, struct task_struct *idle) +{ + if (unlikely(!debug_locks)) + return; + + if (unlikely(per_cpu(hardirqs_enabled, cpu))) { + pr_warn("CPU %u left hardirqs enabled!", cpu); + if (idle) + print_irqtrace_events(idle); + /* Clean it up for when the CPU comes online again. */ + per_cpu(hardirqs_enabled, cpu) = 0; + } +} + static int mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) { @@ -4307,7 +4641,13 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) return 0; } } - if (!hlock->hardirqs_off) { + + /* + * For lock_sync(), don't mark the ENABLED usage, since lock_sync() + * creates no critical section and no extra dependency can be introduced + * by interrupts + */ + if (!hlock->hardirqs_off && !hlock->sync) { if (hlock->read) { if (!mark_lock(curr, hlock, LOCK_ENABLED_HARDIRQ_READ)) @@ -4420,10 +4760,12 @@ unlock: * We must printk outside of the graph_lock: */ if (ret == 2) { + nbcon_cpu_emergency_enter(); printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); print_lock(this); print_irqtrace_events(curr); dump_stack(); + nbcon_cpu_emergency_exit(); } return ret; @@ -4464,6 +4806,8 @@ print_lock_invalid_wait_context(struct task_struct *curr, if (debug_locks_silent) return 0; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("=============================\n"); pr_warn("[ BUG: Invalid wait context ]\n"); @@ -4483,13 +4827,15 @@ print_lock_invalid_wait_context(struct task_struct *curr, pr_warn("stack backtrace:\n"); dump_stack(); + nbcon_cpu_emergency_exit(); + return 0; } /* * Verify the wait_type context. * - * This check validates we takes locks in the right wait-type order; that is it + * This check validates we take locks in the right wait-type order; that is it * ensures that we do not take mutexes inside spinlocks and do not attempt to * acquire spinlocks inside raw_spinlocks and the sort. * @@ -4503,12 +4849,12 @@ print_lock_invalid_wait_context(struct task_struct *curr, */ static int check_wait_context(struct task_struct *curr, struct held_lock *next) { - short next_inner = hlock_class(next)->wait_type_inner; - short next_outer = hlock_class(next)->wait_type_outer; - short curr_inner; + u8 next_inner = hlock_class(next)->wait_type_inner; + u8 next_outer = hlock_class(next)->wait_type_outer; + u8 curr_inner; int depth; - if (!curr->lockdep_depth || !next_inner || next->trylock) + if (!next_inner || next->trylock) return 0; if (!next_outer) @@ -4528,7 +4874,8 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next) for (; depth < curr->lockdep_depth; depth++) { struct held_lock *prev = curr->held_locks + depth; - short prev_inner = hlock_class(prev)->wait_type_inner; + struct lock_class *class = hlock_class(prev); + u8 prev_inner = class->wait_type_inner; if (prev_inner) { /* @@ -4538,6 +4885,14 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next) * Also due to trylocks. */ curr_inner = min(curr_inner, prev_inner); + + /* + * Allow override for annotations -- this is typically + * only valid/needed for code that only exists when + * CONFIG_PREEMPT_RT=n. + */ + if (unlikely(class->lock_type == LD_LOCK_WAIT_OVERRIDE)) + curr_inner = prev_inner; } } @@ -4577,9 +4932,9 @@ static inline int check_wait_context(struct task_struct *curr, /* * Initialize a lock instance's lock-class mapping info: */ -void lockdep_init_map_waits(struct lockdep_map *lock, const char *name, +void lockdep_init_map_type(struct lockdep_map *lock, const char *name, struct lock_class_key *key, int subclass, - short inner, short outer) + u8 inner, u8 outer, u8 lock_type) { int i; @@ -4602,6 +4957,7 @@ void lockdep_init_map_waits(struct lockdep_map *lock, const char *name, lock->wait_type_outer = outer; lock->wait_type_inner = inner; + lock->lock_type = lock_type; /* * No key, no joy, we need to hash something. @@ -4636,21 +4992,52 @@ void lockdep_init_map_waits(struct lockdep_map *lock, const char *name, raw_local_irq_restore(flags); } } -EXPORT_SYMBOL_GPL(lockdep_init_map_waits); +EXPORT_SYMBOL_GPL(lockdep_init_map_type); struct lock_class_key __lockdep_no_validate__; EXPORT_SYMBOL_GPL(__lockdep_no_validate__); +struct lock_class_key __lockdep_no_track__; +EXPORT_SYMBOL_GPL(__lockdep_no_track__); + +#ifdef CONFIG_PROVE_LOCKING +void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn, + lock_print_fn print_fn) +{ + struct lock_class *class = lock->class_cache[0]; + unsigned long flags; + + raw_local_irq_save(flags); + lockdep_recursion_inc(); + + if (!class) + class = register_lock_class(lock, 0, 0); + + if (class) { + WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn); + WARN_ON(class->print_fn && class->print_fn != print_fn); + + class->cmp_fn = cmp_fn; + class->print_fn = print_fn; + } + + lockdep_recursion_finish(); + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn); +#endif + static void print_lock_nested_lock_not_held(struct task_struct *curr, - struct held_lock *hlock, - unsigned long ip) + struct held_lock *hlock) { if (!debug_locks_off()) return; if (debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("==================================\n"); pr_warn("WARNING: Nested lock was not taken\n"); @@ -4671,6 +5058,8 @@ print_lock_nested_lock_not_held(struct task_struct *curr, pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } static int __lock_is_held(const struct lockdep_map *lock, int read); @@ -4686,7 +5075,7 @@ static int __lock_is_held(const struct lockdep_map *lock, int read); static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, int trylock, int read, int check, int hardirqs_off, struct lockdep_map *nest_lock, unsigned long ip, - int references, int pin_count) + int references, int pin_count, int sync) { struct task_struct *curr = current; struct lock_class *class = NULL; @@ -4699,6 +5088,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (unlikely(!debug_locks)) return 0; + if (unlikely(lock->key == &__lockdep_no_track__)) + return 0; + if (!prove_locking || lock->key == &__lockdep_no_validate__) check = 0; @@ -4716,11 +5108,13 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, debug_class_ops_inc(class); if (very_verbose(class)) { + nbcon_cpu_emergency_enter(); printk("\nacquire class [%px] %s", class->key, class->name); if (class->name_version > 1) printk(KERN_CONT "#%d", class->name_version); printk(KERN_CONT "\n"); dump_stack(); + nbcon_cpu_emergency_exit(); } /* @@ -4737,7 +5131,8 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, class_idx = class - lock_classes; - if (depth) { /* we're holding locks */ + if (depth && !sync) { + /* we're holding locks and the new held lock is not a sync */ hlock = curr->held_locks + depth - 1; if (hlock->class_idx == class_idx && nest_lock) { if (!references) @@ -4771,6 +5166,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, hlock->trylock = trylock; hlock->read = read; hlock->check = check; + hlock->sync = !!sync; hlock->hardirqs_off = !!hardirqs_off; hlock->references = references; #ifdef CONFIG_LOCK_STAT @@ -4820,7 +5216,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, chain_key = iterate_chain_key(chain_key, hlock_id(hlock)); if (nest_lock && !__lock_is_held(nest_lock, -1)) { - print_lock_nested_lock_not_held(curr, hlock, ip); + print_lock_nested_lock_not_held(curr, hlock); return 0; } @@ -4832,6 +5228,10 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (!validate_chain(curr, hlock, chain_head, chain_key)) return 0; + /* For lock_sync(), we are done here since no actual critical section */ + if (hlock->sync) + return 1; + curr->curr_chain_key = chain_key; curr->lockdep_depth++; check_chain_key(curr); @@ -4841,6 +5241,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, #endif if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { debug_locks_off(); + nbcon_cpu_emergency_enter(); print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); printk(KERN_DEBUG "depth: %i max: %lu!\n", curr->lockdep_depth, MAX_LOCK_DEPTH); @@ -4848,6 +5249,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, lockdep_print_held_locks(current); debug_show_all_locks(); dump_stack(); + nbcon_cpu_emergency_exit(); return 0; } @@ -4867,6 +5269,8 @@ static void print_unlock_imbalance_bug(struct task_struct *curr, if (debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("=====================================\n"); pr_warn("WARNING: bad unlock balance detected!\n"); @@ -4883,6 +5287,8 @@ static void print_unlock_imbalance_bug(struct task_struct *curr, pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } static noinstr int match_held_lock(const struct held_lock *hlock, @@ -4973,7 +5379,7 @@ static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, hlock->read, hlock->check, hlock->hardirqs_off, hlock->nest_lock, hlock->acquire_ip, - hlock->references, hlock->pin_count)) { + hlock->references, hlock->pin_count, 0)) { case 0: return 1; case 1: @@ -5017,9 +5423,10 @@ __lock_set_class(struct lockdep_map *lock, const char *name, return 0; } - lockdep_init_map_waits(lock, name, key, 0, - lock->wait_type_inner, - lock->wait_type_outer); + lockdep_init_map_type(lock, name, key, 0, + lock->wait_type_inner, + lock->wait_type_outer, + lock->lock_type); class = register_lock_class(lock, subclass, 0); hlock->class_idx = class - lock_classes; @@ -5183,14 +5590,14 @@ int __lock_is_held(const struct lockdep_map *lock, int read) struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) { - if (read == -1 || hlock->read == read) - return 1; + if (read == -1 || !!hlock->read == read) + return LOCK_STATE_HELD; - return 0; + return LOCK_STATE_NOT_HELD; } } - return 0; + return LOCK_STATE_NOT_HELD; } static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) @@ -5211,7 +5618,7 @@ static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) * be guessable and still allows some pin nesting in * our u32 pin_count. */ - cookie.val = 1 + (prandom_u32() >> 16); + cookie.val = 1 + (sched_clock() & 0xffff); hlock->pin_count += cookie.val; return cookie; } @@ -5290,6 +5697,7 @@ static noinstr void check_flags(unsigned long flags) } } +#ifndef CONFIG_PREEMPT_RT /* * We dont accurately track softirq state in e.g. * hardirq contexts (such as on 4KSTACKS), so only @@ -5304,6 +5712,7 @@ static noinstr void check_flags(unsigned long flags) DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); } } +#endif if (!debug_locks) print_irqtrace_events(current); @@ -5440,7 +5849,7 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass, lockdep_recursion_inc(); __lock_acquire(lock, subclass, trylock, read, check, - irqs_disabled_flags(flags), nest_lock, ip, 0, 0); + irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 0); lockdep_recursion_finish(); raw_local_irq_restore(flags); } @@ -5452,7 +5861,8 @@ void lock_release(struct lockdep_map *lock, unsigned long ip) trace_lock_release(lock, ip); - if (unlikely(!lockdep_enabled())) + if (unlikely(!lockdep_enabled() || + lock->key == &__lockdep_no_track__)) return; raw_local_irq_save(flags); @@ -5466,13 +5876,45 @@ void lock_release(struct lockdep_map *lock, unsigned long ip) } EXPORT_SYMBOL_GPL(lock_release); +/* + * lock_sync() - A special annotation for synchronize_{s,}rcu()-like API. + * + * No actual critical section is created by the APIs annotated with this: these + * APIs are used to wait for one or multiple critical sections (on other CPUs + * or threads), and it means that calling these APIs inside these critical + * sections is potential deadlock. + */ +void lock_sync(struct lockdep_map *lock, unsigned subclass, int read, + int check, struct lockdep_map *nest_lock, unsigned long ip) +{ + unsigned long flags; + + if (unlikely(!lockdep_enabled())) + return; + + raw_local_irq_save(flags); + check_flags(flags); + + lockdep_recursion_inc(); + __lock_acquire(lock, subclass, 0, read, check, + irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 1); + check_chain_key(current); + lockdep_recursion_finish(); + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(lock_sync); + noinstr int lock_is_held_type(const struct lockdep_map *lock, int read) { unsigned long flags; - int ret = 0; + int ret = LOCK_STATE_NOT_HELD; + /* + * Avoid false negative lockdep_assert_held() and + * lockdep_assert_not_held(). + */ if (unlikely(!lockdep_enabled())) - return 1; /* avoid false negative lockdep_assert_held() */ + return LOCK_STATE_UNKNOWN; raw_local_irq_save(flags); check_flags(flags); @@ -5551,6 +5993,8 @@ static void print_lock_contention_bug(struct task_struct *curr, if (debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("=================================\n"); pr_warn("WARNING: bad contention detected!\n"); @@ -5567,6 +6011,8 @@ static void print_lock_contention_bug(struct task_struct *curr, pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } static void @@ -5586,6 +6032,9 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip) if (DEBUG_LOCKS_WARN_ON(!depth)) return; + if (unlikely(lock->key == &__lockdep_no_track__)) + return; + hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) { print_lock_contention_bug(curr, lock, ip); @@ -5628,6 +6077,9 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip) if (DEBUG_LOCKS_WARN_ON(!depth)) return; + if (unlikely(lock->key == &__lockdep_no_track__)) + return; + hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) { print_lock_contention_bug(curr, lock, _RET_IP_); @@ -5662,7 +6114,7 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; - trace_lock_acquired(lock, ip); + trace_lock_contended(lock, ip); if (unlikely(!lock_stat || !lockdep_enabled())) return; @@ -5680,7 +6132,7 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; - trace_lock_contended(lock, ip); + trace_lock_acquired(lock, ip); if (unlikely(!lock_stat || !lockdep_enabled())) return; @@ -5799,6 +6251,8 @@ static void zap_class(struct pending_free *pf, struct lock_class *class) WRITE_ONCE(class->name, NULL); nr_lock_classes--; __clear_bit(class - lock_classes, lock_classes_in_use); + if (class - lock_classes == max_lock_class_idx) + max_lock_class_idx--; } else { WARN_ONCE(true, "%s() failed for class %s\n", __func__, class->name); @@ -5810,13 +6264,10 @@ static void zap_class(struct pending_free *pf, struct lock_class *class) static void reinit_class(struct lock_class *class) { - void *const p = class; - const unsigned int offset = offsetof(struct lock_class, key); - WARN_ON_ONCE(!class->lock_entry.next); WARN_ON_ONCE(!list_empty(&class->locks_after)); WARN_ON_ONCE(!list_empty(&class->locks_before)); - memset(p + offset, 0, sizeof(*class) - offset); + memset_startat(class, 0, key); WARN_ON_ONCE(!class->lock_entry.next); WARN_ON_ONCE(!list_empty(&class->locks_after)); WARN_ON_ONCE(!list_empty(&class->locks_before)); @@ -5841,25 +6292,27 @@ static struct pending_free *get_pending_free(void) static void free_zapped_rcu(struct rcu_head *cb); /* - * Schedule an RCU callback if no RCU callback is pending. Must be called with - * the graph lock held. - */ -static void call_rcu_zapped(struct pending_free *pf) +* See if we need to queue an RCU callback, must called with +* the lockdep lock held, returns false if either we don't have +* any pending free or the callback is already scheduled. +* Otherwise, a call_rcu() must follow this function call. +*/ +static bool prepare_call_rcu_zapped(struct pending_free *pf) { WARN_ON_ONCE(inside_selftest()); if (list_empty(&pf->zapped)) - return; + return false; if (delayed_free.scheduled) - return; + return false; delayed_free.scheduled = true; WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf); delayed_free.index ^= 1; - call_rcu(&delayed_free.rcu_head, free_zapped_rcu); + return true; } /* The caller must hold the graph lock. May be called from RCU context. */ @@ -5885,6 +6338,7 @@ static void free_zapped_rcu(struct rcu_head *ch) { struct pending_free *pf; unsigned long flags; + bool need_callback; if (WARN_ON_ONCE(ch != &delayed_free.rcu_head)) return; @@ -5896,14 +6350,18 @@ static void free_zapped_rcu(struct rcu_head *ch) pf = delayed_free.pf + (delayed_free.index ^ 1); __free_zapped_classes(pf); delayed_free.scheduled = false; + need_callback = + prepare_call_rcu_zapped(delayed_free.pf + delayed_free.index); + lockdep_unlock(); + raw_local_irq_restore(flags); /* - * If there's anything on the open list, close and start a new callback. - */ - call_rcu_zapped(delayed_free.pf + delayed_free.index); + * If there's pending free and its callback has not been scheduled, + * queue an RCU callback. + */ + if (need_callback) + call_rcu(&delayed_free.rcu_head, free_zapped_rcu); - lockdep_unlock(); - raw_local_irq_restore(flags); } /* @@ -5943,6 +6401,7 @@ static void lockdep_free_key_range_reg(void *start, unsigned long size) { struct pending_free *pf; unsigned long flags; + bool need_callback; init_data_structures_once(); @@ -5950,10 +6409,11 @@ static void lockdep_free_key_range_reg(void *start, unsigned long size) lockdep_lock(); pf = get_pending_free(); __lockdep_free_key_range(pf, start, size); - call_rcu_zapped(pf); + need_callback = prepare_call_rcu_zapped(pf); lockdep_unlock(); raw_local_irq_restore(flags); - + if (need_callback) + call_rcu(&delayed_free.rcu_head, free_zapped_rcu); /* * Wait for any possible iterators from look_up_lock_class() to pass * before continuing to free the memory they refer to. @@ -6047,6 +6507,7 @@ static void lockdep_reset_lock_reg(struct lockdep_map *lock) struct pending_free *pf; unsigned long flags; int locked; + bool need_callback = false; raw_local_irq_save(flags); locked = graph_lock(); @@ -6055,11 +6516,13 @@ static void lockdep_reset_lock_reg(struct lockdep_map *lock) pf = get_pending_free(); __lockdep_reset_lock(pf, lock); - call_rcu_zapped(pf); + need_callback = prepare_call_rcu_zapped(pf); graph_unlock(); out_irq: raw_local_irq_restore(flags); + if (need_callback) + call_rcu(&delayed_free.rcu_head, free_zapped_rcu); } /* @@ -6089,7 +6552,13 @@ void lockdep_reset_lock(struct lockdep_map *lock) lockdep_reset_lock_reg(lock); } -/* Unregister a dynamically allocated key. */ +/* + * Unregister a dynamically allocated key. + * + * Unlike lockdep_register_key(), a search is always done to find a matching + * key irrespective of debug_locks to avoid potential invalid access to freed + * memory in lock_class entry. + */ void lockdep_unregister_key(struct lock_class_key *key) { struct hlist_head *hash_head = keyhashentry(key); @@ -6097,6 +6566,7 @@ void lockdep_unregister_key(struct lock_class_key *key) struct pending_free *pf; unsigned long flags; bool found = false; + bool need_callback = false; might_sleep(); @@ -6104,10 +6574,8 @@ void lockdep_unregister_key(struct lock_class_key *key) return; raw_local_irq_save(flags); - if (!graph_lock()) - goto out_irq; + lockdep_lock(); - pf = get_pending_free(); hlist_for_each_entry_rcu(k, hash_head, hash_entry) { if (k == key) { hlist_del_rcu(&k->hash_entry); @@ -6115,13 +6583,18 @@ void lockdep_unregister_key(struct lock_class_key *key) break; } } - WARN_ON_ONCE(!found); - __lockdep_free_key_range(pf, key, 1); - call_rcu_zapped(pf); - graph_unlock(); -out_irq: + WARN_ON_ONCE(!found && debug_locks); + if (found) { + pf = get_pending_free(); + __lockdep_free_key_range(pf, key, 1); + need_callback = prepare_call_rcu_zapped(pf); + } + lockdep_unlock(); raw_local_irq_restore(flags); + if (need_callback) + call_rcu(&delayed_free.rcu_head, free_zapped_rcu); + /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */ synchronize_rcu(); } @@ -6129,17 +6602,17 @@ EXPORT_SYMBOL_GPL(lockdep_unregister_key); void __init lockdep_init(void) { - printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); + pr_info("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); - printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); - printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); - printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); - printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); - printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); - printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); - printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); + pr_info("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); + pr_info("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); + pr_info("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); + pr_info("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); + pr_info("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); + pr_info("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); + pr_info("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); - printk(" memory used by lock dependency info: %zu kB\n", + pr_info(" memory used by lock dependency info: %zu kB\n", (sizeof(lock_classes) + sizeof(lock_classes_in_use) + sizeof(classhash_table) + @@ -6157,12 +6630,12 @@ void __init lockdep_init(void) ); #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) - printk(" memory used for stack traces: %zu kB\n", + pr_info(" memory used for stack traces: %zu kB\n", (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024 ); #endif - printk(" per task-struct memory footprint: %zu bytes\n", + pr_info(" per task-struct memory footprint: %zu bytes\n", sizeof(((struct task_struct *)NULL)->held_locks)); } @@ -6175,6 +6648,8 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from, if (debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("=========================\n"); pr_warn("WARNING: held lock freed!\n"); @@ -6187,6 +6662,8 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from, pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } static inline int not_in_range(const void* mem_from, unsigned long mem_len, @@ -6233,6 +6710,8 @@ static void print_held_locks_bug(void) if (debug_locks_silent) return; + nbcon_cpu_emergency_enter(); + pr_warn("\n"); pr_warn("====================================\n"); pr_warn("WARNING: %s/%d still has locks held!\n", @@ -6242,6 +6721,8 @@ static void print_held_locks_bug(void) lockdep_print_held_locks(current); pr_warn("\nstack backtrace:\n"); dump_stack(); + + nbcon_cpu_emergency_exit(); } void debug_check_no_locks_held(void) @@ -6299,6 +6780,7 @@ asmlinkage __visible void lockdep_sys_exit(void) if (unlikely(curr->lockdep_depth)) { if (!debug_locks_off()) return; + nbcon_cpu_emergency_enter(); pr_warn("\n"); pr_warn("================================================\n"); pr_warn("WARNING: lock held when returning to user space!\n"); @@ -6307,6 +6789,7 @@ asmlinkage __visible void lockdep_sys_exit(void) pr_warn("%s/%d is leaving the kernel with locks still held!\n", curr->comm, curr->pid); lockdep_print_held_locks(curr); + nbcon_cpu_emergency_exit(); } /* @@ -6319,8 +6802,11 @@ asmlinkage __visible void lockdep_sys_exit(void) void lockdep_rcu_suspicious(const char *file, const int line, const char *s) { struct task_struct *curr = current; + int dl = READ_ONCE(debug_locks); + bool rcu = warn_rcu_enter(); /* Note: the following can be executed concurrently, so be careful. */ + nbcon_cpu_emergency_enter(); pr_warn("\n"); pr_warn("=============================\n"); pr_warn("WARNING: suspicious RCU usage\n"); @@ -6328,15 +6814,16 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) pr_warn("-----------------------------\n"); pr_warn("%s:%d %s!\n", file, line, s); pr_warn("\nother info that might help us debug this:\n\n"); - pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n", + pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s", !rcu_lockdep_current_cpu_online() ? "RCU used illegally from offline CPU!\n" : "", - rcu_scheduler_active, debug_locks); + rcu_scheduler_active, dl, + dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n"); /* * If a CPU is in the RCU-free window in idle (ie: in the section - * between rcu_idle_enter() and rcu_idle_exit(), then RCU + * between ct_idle_enter() and ct_idle_exit(), then RCU * considers that CPU to be in an "extended quiescent state", * which means that RCU will be completely ignoring that CPU. * Therefore, rcu_read_lock() and friends have absolutely no @@ -6358,5 +6845,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); + nbcon_cpu_emergency_exit(); + warn_rcu_exit(rcu); } EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |