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authorIngo Molnar <mingo@kernel.org>2020-08-06 10:16:38 +0200
committerIngo Molnar <mingo@kernel.org>2020-08-06 10:16:38 +0200
commita703f3633ff1d982bc4adfe7e0921bedb1701216 (patch)
treeeb85b29a0bbcb29045e197ab77e18ffc8649a722 /kernel/locking
parenta7ef9b28aa8d72a1656fa6f0a01bbd1493886317 (diff)
parentb5e6a027bd327daa679ca55182a920659e2cbb90 (diff)
Merge branch 'WIP.locking/seqlocks' into locking/urgent
Pick up the full seqlock series PeterZ is working on. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/lockdep.c80
1 files changed, 59 insertions, 21 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 29a8de4c50b9..c9ea05edce25 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -395,7 +395,7 @@ void lockdep_init_task(struct task_struct *task)
static __always_inline void lockdep_recursion_finish(void)
{
- if (WARN_ON_ONCE(--current->lockdep_recursion))
+ if (WARN_ON_ONCE((--current->lockdep_recursion) & LOCKDEP_RECURSION_MASK))
current->lockdep_recursion = 0;
}
@@ -2062,9 +2062,9 @@ print_bad_irq_dependency(struct task_struct *curr,
pr_warn("-----------------------------------------------------\n");
pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
curr->comm, task_pid_nr(curr),
- curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
+ lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
- curr->hardirqs_enabled,
+ lockdep_hardirqs_enabled(),
curr->softirqs_enabled);
print_lock(next);
@@ -3331,9 +3331,9 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
curr->comm, task_pid_nr(curr),
- lockdep_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
+ lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
- lockdep_hardirqs_enabled(curr),
+ lockdep_hardirqs_enabled(),
lockdep_softirqs_enabled(curr));
print_lock(this);
@@ -3646,10 +3646,19 @@ static void __trace_hardirqs_on_caller(void)
*/
void lockdep_hardirqs_on_prepare(unsigned long ip)
{
- if (unlikely(!debug_locks || current->lockdep_recursion))
+ if (unlikely(!debug_locks))
+ return;
+
+ /*
+ * NMIs do not (and cannot) track lock dependencies, nothing to do.
+ */
+ if (unlikely(in_nmi()))
return;
- if (unlikely(current->hardirqs_enabled)) {
+ if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
+ return;
+
+ if (unlikely(lockdep_hardirqs_enabled())) {
/*
* Neither irq nor preemption are disabled here
* so this is racy by nature but losing one hit
@@ -3677,7 +3686,7 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
* Can't allow enabling interrupts while in an interrupt handler,
* that's general bad form and such. Recursion, limited stack etc..
*/
- if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+ if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
return;
current->hardirq_chain_key = current->curr_chain_key;
@@ -3692,10 +3701,30 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
{
struct task_struct *curr = current;
- if (unlikely(!debug_locks || curr->lockdep_recursion))
+ if (unlikely(!debug_locks))
return;
- if (curr->hardirqs_enabled) {
+ /*
+ * NMIs can happen in the middle of local_irq_{en,dis}able() where the
+ * tracking state and hardware state are out of sync.
+ *
+ * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
+ * and not rely on hardware state like normal interrupts.
+ */
+ if (unlikely(in_nmi())) {
+ /*
+ * Skip:
+ * - recursion check, because NMI can hit lockdep;
+ * - hardware state check, because above;
+ * - chain_key check, see lockdep_hardirqs_on_prepare().
+ */
+ goto skip_checks;
+ }
+
+ if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
+ return;
+
+ if (lockdep_hardirqs_enabled()) {
/*
* Neither irq nor preemption are disabled here
* so this is racy by nature but losing one hit
@@ -3720,8 +3749,9 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
current->curr_chain_key);
+skip_checks:
/* we'll do an OFF -> ON transition: */
- curr->hardirqs_enabled = 1;
+ this_cpu_write(hardirqs_enabled, 1);
curr->hardirq_enable_ip = ip;
curr->hardirq_enable_event = ++curr->irq_events;
debug_atomic_inc(hardirqs_on_events);
@@ -3735,7 +3765,15 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
{
struct task_struct *curr = current;
- if (unlikely(!debug_locks || curr->lockdep_recursion))
+ if (unlikely(!debug_locks))
+ return;
+
+ /*
+ * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
+ * they will restore the software state. This ensures the software
+ * state is consistent inside NMIs as well.
+ */
+ if (unlikely(!in_nmi() && (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)))
return;
/*
@@ -3745,11 +3783,11 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
- if (curr->hardirqs_enabled) {
+ if (lockdep_hardirqs_enabled()) {
/*
* We have done an ON -> OFF transition:
*/
- curr->hardirqs_enabled = 0;
+ this_cpu_write(hardirqs_enabled, 0);
curr->hardirq_disable_ip = ip;
curr->hardirq_disable_event = ++curr->irq_events;
debug_atomic_inc(hardirqs_off_events);
@@ -3794,7 +3832,7 @@ void lockdep_softirqs_on(unsigned long ip)
* usage bit for all held locks, if hardirqs are
* enabled too:
*/
- if (curr->hardirqs_enabled)
+ if (lockdep_hardirqs_enabled())
mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
lockdep_recursion_finish();
}
@@ -3843,7 +3881,7 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
*/
if (!hlock->trylock) {
if (hlock->read) {
- if (curr->hardirq_context)
+ if (lockdep_hardirq_context())
if (!mark_lock(curr, hlock,
LOCK_USED_IN_HARDIRQ_READ))
return 0;
@@ -3852,7 +3890,7 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
LOCK_USED_IN_SOFTIRQ_READ))
return 0;
} else {
- if (curr->hardirq_context)
+ if (lockdep_hardirq_context())
if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
return 0;
if (curr->softirq_context)
@@ -3890,7 +3928,7 @@ lock_used:
static inline unsigned int task_irq_context(struct task_struct *task)
{
- return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context +
+ return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
}
@@ -3983,7 +4021,7 @@ static inline short task_wait_context(struct task_struct *curr)
* Set appropriate wait type for the context; for IRQs we have to take
* into account force_irqthread as that is implied by PREEMPT_RT.
*/
- if (curr->hardirq_context) {
+ if (lockdep_hardirq_context()) {
/*
* Check if force_irqthreads will run us threaded.
*/
@@ -4826,11 +4864,11 @@ static void check_flags(unsigned long flags)
return;
if (irqs_disabled_flags(flags)) {
- if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
+ if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
printk("possible reason: unannotated irqs-off.\n");
}
} else {
- if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
+ if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
printk("possible reason: unannotated irqs-on.\n");
}
}