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-rw-r--r--kernel/Makefile3
-rw-r--r--kernel/cpuset.c10
-rw-r--r--kernel/exit.c5
-rw-r--r--kernel/fork.c4
-rw-r--r--kernel/mutex-debug.c464
-rw-r--r--kernel/mutex-debug.h134
-rw-r--r--kernel/mutex.c325
-rw-r--r--kernel/mutex.h35
-rw-r--r--kernel/sched.c1
9 files changed, 975 insertions, 6 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index 4f5a1453093a..a940bac02837 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -7,8 +7,9 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
sysctl.o capability.o ptrace.o timer.o user.o \
signal.o sys.o kmod.o workqueue.o pid.o \
rcupdate.o intermodule.o extable.o params.o posix-timers.o \
- kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o
+ kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o
+obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
obj-$(CONFIG_FUTEX) += futex.o
obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
obj-$(CONFIG_SMP) += cpu.o spinlock.o
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index eab64e23bcae..2a75e44e1a41 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1513,7 +1513,7 @@ static int cpuset_add_file(struct dentry *dir, const struct cftype *cft)
struct dentry *dentry;
int error;
- down(&dir->d_inode->i_sem);
+ mutex_lock(&dir->d_inode->i_mutex);
dentry = cpuset_get_dentry(dir, cft->name);
if (!IS_ERR(dentry)) {
error = cpuset_create_file(dentry, 0644 | S_IFREG);
@@ -1522,7 +1522,7 @@ static int cpuset_add_file(struct dentry *dir, const struct cftype *cft)
dput(dentry);
} else
error = PTR_ERR(dentry);
- up(&dir->d_inode->i_sem);
+ mutex_unlock(&dir->d_inode->i_mutex);
return error;
}
@@ -1793,7 +1793,7 @@ static long cpuset_create(struct cpuset *parent, const char *name, int mode)
/*
* Release manage_sem before cpuset_populate_dir() because it
- * will down() this new directory's i_sem and if we race with
+ * will down() this new directory's i_mutex and if we race with
* another mkdir, we might deadlock.
*/
up(&manage_sem);
@@ -1812,7 +1812,7 @@ static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
struct cpuset *c_parent = dentry->d_parent->d_fsdata;
- /* the vfs holds inode->i_sem already */
+ /* the vfs holds inode->i_mutex already */
return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR);
}
@@ -1823,7 +1823,7 @@ static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
struct cpuset *parent;
char *pathbuf = NULL;
- /* the vfs holds both inode->i_sem already */
+ /* the vfs holds both inode->i_mutex already */
down(&manage_sem);
cpuset_update_task_memory_state();
diff --git a/kernel/exit.c b/kernel/exit.c
index caceabf3f230..309a46fa16f8 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -29,6 +29,7 @@
#include <linux/syscalls.h>
#include <linux/signal.h>
#include <linux/cn_proc.h>
+#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -869,6 +870,10 @@ fastcall NORET_TYPE void do_exit(long code)
mpol_free(tsk->mempolicy);
tsk->mempolicy = NULL;
#endif
+ /*
+ * If DEBUG_MUTEXES is on, make sure we are holding no locks:
+ */
+ mutex_debug_check_no_locks_held(tsk);
/* PF_DEAD causes final put_task_struct after we schedule. */
preempt_disable();
diff --git a/kernel/fork.c b/kernel/fork.c
index 72e3252c6763..b18d64554feb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -979,6 +979,10 @@ static task_t *copy_process(unsigned long clone_flags,
}
#endif
+#ifdef CONFIG_DEBUG_MUTEXES
+ p->blocked_on = NULL; /* not blocked yet */
+#endif
+
p->tgid = p->pid;
if (clone_flags & CLONE_THREAD)
p->tgid = current->tgid;
diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
new file mode 100644
index 000000000000..4fcb051a8b9e
--- /dev/null
+++ b/kernel/mutex-debug.c
@@ -0,0 +1,464 @@
+/*
+ * kernel/mutex-debug.c
+ *
+ * Debugging code for mutexes
+ *
+ * Started by Ingo Molnar:
+ *
+ * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * lock debugging, locking tree, deadlock detection started by:
+ *
+ * Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
+ * Released under the General Public License (GPL).
+ */
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+
+#include <asm/mutex.h>
+
+#include "mutex-debug.h"
+
+/*
+ * We need a global lock when we walk through the multi-process
+ * lock tree. Only used in the deadlock-debugging case.
+ */
+DEFINE_SPINLOCK(debug_mutex_lock);
+
+/*
+ * All locks held by all tasks, in a single global list:
+ */
+LIST_HEAD(debug_mutex_held_locks);
+
+/*
+ * In the debug case we carry the caller's instruction pointer into
+ * other functions, but we dont want the function argument overhead
+ * in the nondebug case - hence these macros:
+ */
+#define __IP_DECL__ , unsigned long ip
+#define __IP__ , ip
+#define __RET_IP__ , (unsigned long)__builtin_return_address(0)
+
+/*
+ * "mutex debugging enabled" flag. We turn it off when we detect
+ * the first problem because we dont want to recurse back
+ * into the tracing code when doing error printk or
+ * executing a BUG():
+ */
+int debug_mutex_on = 1;
+
+static void printk_task(struct task_struct *p)
+{
+ if (p)
+ printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
+ else
+ printk("<none>");
+}
+
+static void printk_ti(struct thread_info *ti)
+{
+ if (ti)
+ printk_task(ti->task);
+ else
+ printk("<none>");
+}
+
+static void printk_task_short(struct task_struct *p)
+{
+ if (p)
+ printk("%s/%d [%p, %3d]", p->comm, p->pid, p, p->prio);
+ else
+ printk("<none>");
+}
+
+static void printk_lock(struct mutex *lock, int print_owner)
+{
+ printk(" [%p] {%s}\n", lock, lock->name);
+
+ if (print_owner && lock->owner) {
+ printk(".. held by: ");
+ printk_ti(lock->owner);
+ printk("\n");
+ }
+ if (lock->owner) {
+ printk("... acquired at: ");
+ print_symbol("%s\n", lock->acquire_ip);
+ }
+}
+
+/*
+ * printk locks held by a task:
+ */
+static void show_task_locks(struct task_struct *p)
+{
+ switch (p->state) {
+ case TASK_RUNNING: printk("R"); break;
+ case TASK_INTERRUPTIBLE: printk("S"); break;
+ case TASK_UNINTERRUPTIBLE: printk("D"); break;
+ case TASK_STOPPED: printk("T"); break;
+ case EXIT_ZOMBIE: printk("Z"); break;
+ case EXIT_DEAD: printk("X"); break;
+ default: printk("?"); break;
+ }
+ printk_task(p);
+ if (p->blocked_on) {
+ struct mutex *lock = p->blocked_on->lock;
+
+ printk(" blocked on mutex:");
+ printk_lock(lock, 1);
+ } else
+ printk(" (not blocked on mutex)\n");
+}
+
+/*
+ * printk all locks held in the system (if filter == NULL),
+ * or all locks belonging to a single task (if filter != NULL):
+ */
+void show_held_locks(struct task_struct *filter)
+{
+ struct list_head *curr, *cursor = NULL;
+ struct mutex *lock;
+ struct thread_info *t;
+ unsigned long flags;
+ int count = 0;
+
+ if (filter) {
+ printk("------------------------------\n");
+ printk("| showing all locks held by: | (");
+ printk_task_short(filter);
+ printk("):\n");
+ printk("------------------------------\n");
+ } else {
+ printk("---------------------------\n");
+ printk("| showing all locks held: |\n");
+ printk("---------------------------\n");
+ }
+
+ /*
+ * Play safe and acquire the global trace lock. We
+ * cannot printk with that lock held so we iterate
+ * very carefully:
+ */
+next:
+ debug_spin_lock_save(&debug_mutex_lock, flags);
+ list_for_each(curr, &debug_mutex_held_locks) {
+ if (cursor && curr != cursor)
+ continue;
+ lock = list_entry(curr, struct mutex, held_list);
+ t = lock->owner;
+ if (filter && (t != filter->thread_info))
+ continue;
+ count++;
+ cursor = curr->next;
+ debug_spin_lock_restore(&debug_mutex_lock, flags);
+
+ printk("\n#%03d: ", count);
+ printk_lock(lock, filter ? 0 : 1);
+ goto next;
+ }
+ debug_spin_lock_restore(&debug_mutex_lock, flags);
+ printk("\n");
+}
+
+void mutex_debug_show_all_locks(void)
+{
+ struct task_struct *g, *p;
+ int count = 10;
+ int unlock = 1;
+
+ printk("\nShowing all blocking locks in the system:\n");
+
+ /*
+ * Here we try to get the tasklist_lock as hard as possible,
+ * if not successful after 2 seconds we ignore it (but keep
+ * trying). This is to enable a debug printout even if a
+ * tasklist_lock-holding task deadlocks or crashes.
+ */
+retry:
+ if (!read_trylock(&tasklist_lock)) {
+ if (count == 10)
+ printk("hm, tasklist_lock locked, retrying... ");
+ if (count) {
+ count--;
+ printk(" #%d", 10-count);
+ mdelay(200);
+ goto retry;
+ }
+ printk(" ignoring it.\n");
+ unlock = 0;
+ }
+ if (count != 10)
+ printk(" locked it.\n");
+
+ do_each_thread(g, p) {
+ show_task_locks(p);
+ if (!unlock)
+ if (read_trylock(&tasklist_lock))
+ unlock = 1;
+ } while_each_thread(g, p);
+
+ printk("\n");
+ show_held_locks(NULL);
+ printk("=============================================\n\n");
+
+ if (unlock)
+ read_unlock(&tasklist_lock);
+}
+
+static void report_deadlock(struct task_struct *task, struct mutex *lock,
+ struct mutex *lockblk, unsigned long ip)
+{
+ printk("\n%s/%d is trying to acquire this lock:\n",
+ current->comm, current->pid);
+ printk_lock(lock, 1);
+ printk("... trying at: ");
+ print_symbol("%s\n", ip);
+ show_held_locks(current);
+
+ if (lockblk) {
+ printk("but %s/%d is deadlocking current task %s/%d!\n\n",
+ task->comm, task->pid, current->comm, current->pid);
+ printk("\n%s/%d is blocked on this lock:\n",
+ task->comm, task->pid);
+ printk_lock(lockblk, 1);
+
+ show_held_locks(task);
+
+ printk("\n%s/%d's [blocked] stackdump:\n\n",
+ task->comm, task->pid);
+ show_stack(task, NULL);
+ }
+
+ printk("\n%s/%d's [current] stackdump:\n\n",
+ current->comm, current->pid);
+ dump_stack();
+ mutex_debug_show_all_locks();
+ printk("[ turning off deadlock detection. Please report this. ]\n\n");
+ local_irq_disable();
+}
+
+/*
+ * Recursively check for mutex deadlocks:
+ */
+static int check_deadlock(struct mutex *lock, int depth,
+ struct thread_info *ti, unsigned long ip)
+{
+ struct mutex *lockblk;
+ struct task_struct *task;
+
+ if (!debug_mutex_on)
+ return 0;
+
+ ti = lock->owner;
+ if (!ti)
+ return 0;
+
+ task = ti->task;
+ lockblk = NULL;
+ if (task->blocked_on)
+ lockblk = task->blocked_on->lock;
+
+ /* Self-deadlock: */
+ if (current == task) {
+ DEBUG_OFF();
+ if (depth)
+ return 1;
+ printk("\n==========================================\n");
+ printk( "[ BUG: lock recursion deadlock detected! |\n");
+ printk( "------------------------------------------\n");
+ report_deadlock(task, lock, NULL, ip);
+ return 0;
+ }
+
+ /* Ugh, something corrupted the lock data structure? */
+ if (depth > 20) {
+ DEBUG_OFF();
+ printk("\n===========================================\n");
+ printk( "[ BUG: infinite lock dependency detected!? |\n");
+ printk( "-------------------------------------------\n");
+ report_deadlock(task, lock, lockblk, ip);
+ return 0;
+ }
+
+ /* Recursively check for dependencies: */
+ if (lockblk && check_deadlock(lockblk, depth+1, ti, ip)) {
+ printk("\n============================================\n");
+ printk( "[ BUG: circular locking deadlock detected! ]\n");
+ printk( "--------------------------------------------\n");
+ report_deadlock(task, lock, lockblk, ip);
+ return 0;
+ }
+ return 0;
+}
+
+/*
+ * Called when a task exits, this function checks whether the
+ * task is holding any locks, and reports the first one if so:
+ */
+void mutex_debug_check_no_locks_held(struct task_struct *task)
+{
+ struct list_head *curr, *next;
+ struct thread_info *t;
+ unsigned long flags;
+ struct mutex *lock;
+
+ if (!debug_mutex_on)
+ return;
+
+ debug_spin_lock_save(&debug_mutex_lock, flags);
+ list_for_each_safe(curr, next, &debug_mutex_held_locks) {
+ lock = list_entry(curr, struct mutex, held_list);
+ t = lock->owner;
+ if (t != task->thread_info)
+ continue;
+ list_del_init(curr);
+ DEBUG_OFF();
+ debug_spin_lock_restore(&debug_mutex_lock, flags);
+
+ printk("BUG: %s/%d, lock held at task exit time!\n",
+ task->comm, task->pid);
+ printk_lock(lock, 1);
+ if (lock->owner != task->thread_info)
+ printk("exiting task is not even the owner??\n");
+ return;
+ }
+ debug_spin_lock_restore(&debug_mutex_lock, flags);
+}
+
+/*
+ * Called when kernel memory is freed (or unmapped), or if a mutex
+ * is destroyed or reinitialized - this code checks whether there is
+ * any held lock in the memory range of <from> to <to>:
+ */
+void mutex_debug_check_no_locks_freed(const void *from, const void *to)
+{
+ struct list_head *curr, *next;
+ unsigned long flags;
+ struct mutex *lock;
+ void *lock_addr;
+
+ if (!debug_mutex_on)
+ return;
+
+ debug_spin_lock_save(&debug_mutex_lock, flags);
+ list_for_each_safe(curr, next, &debug_mutex_held_locks) {
+ lock = list_entry(curr, struct mutex, held_list);
+ lock_addr = lock;
+ if (lock_addr < from || lock_addr >= to)
+ continue;
+ list_del_init(curr);
+ DEBUG_OFF();
+ debug_spin_lock_restore(&debug_mutex_lock, flags);
+
+ printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
+ current->comm, current->pid, lock, from, to);
+ dump_stack();
+ printk_lock(lock, 1);
+ if (lock->owner != current_thread_info())
+ printk("freeing task is not even the owner??\n");
+ return;
+ }
+ debug_spin_lock_restore(&debug_mutex_lock, flags);
+}
+
+/*
+ * Must be called with lock->wait_lock held.
+ */
+void debug_mutex_set_owner(struct mutex *lock,
+ struct thread_info *new_owner __IP_DECL__)
+{
+ lock->owner = new_owner;
+ DEBUG_WARN_ON(!list_empty(&lock->held_list));
+ if (debug_mutex_on) {
+ list_add_tail(&lock->held_list, &debug_mutex_held_locks);
+ lock->acquire_ip = ip;
+ }
+}
+
+void debug_mutex_init_waiter(struct mutex_waiter *waiter)
+{
+ memset(waiter, 0x11, sizeof(*waiter));
+ waiter->magic = waiter;
+ INIT_LIST_HEAD(&waiter->list);
+}
+
+void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
+{
+ SMP_DEBUG_WARN_ON(!spin_is_locked(&lock->wait_lock));
+ DEBUG_WARN_ON(list_empty(&lock->wait_list));
+ DEBUG_WARN_ON(waiter->magic != waiter);
+ DEBUG_WARN_ON(list_empty(&waiter->list));
+}
+
+void debug_mutex_free_waiter(struct mutex_waiter *waiter)
+{
+ DEBUG_WARN_ON(!list_empty(&waiter->list));
+ memset(waiter, 0x22, sizeof(*waiter));
+}
+
+void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+ struct thread_info *ti __IP_DECL__)
+{
+ SMP_DEBUG_WARN_ON(!spin_is_locked(&lock->wait_lock));
+ check_deadlock(lock, 0, ti, ip);
+ /* Mark the current thread as blocked on the lock: */
+ ti->task->blocked_on = waiter;
+ waiter->lock = lock;
+}
+
+void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+ struct thread_info *ti)
+{
+ DEBUG_WARN_ON(list_empty(&waiter->list));
+ DEBUG_WARN_ON(waiter->task != ti->task);
+ DEBUG_WARN_ON(ti->task->blocked_on != waiter);
+ ti->task->blocked_on = NULL;
+
+ list_del_init(&waiter->list);
+ waiter->task = NULL;
+}
+
+void debug_mutex_unlock(struct mutex *lock)
+{
+ DEBUG_WARN_ON(lock->magic != lock);
+ DEBUG_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
+ DEBUG_WARN_ON(lock->owner != current_thread_info());
+ if (debug_mutex_on) {
+ DEBUG_WARN_ON(list_empty(&lock->held_list));
+ list_del_init(&lock->held_list);
+ }
+}
+
+void debug_mutex_init(struct mutex *lock, const char *name)
+{
+ /*
+ * Make sure we are not reinitializing a held lock:
+ */
+ mutex_debug_check_no_locks_freed((void *)lock, (void *)(lock + 1));
+ lock->owner = NULL;
+ INIT_LIST_HEAD(&lock->held_list);
+ lock->name = name;
+ lock->magic = lock;
+}
+
+/***
+ * mutex_destroy - mark a mutex unusable
+ * @lock: the mutex to be destroyed
+ *
+ * This function marks the mutex uninitialized, and any subsequent
+ * use of the mutex is forbidden. The mutex must not be locked when
+ * this function is called.
+ */
+void fastcall mutex_destroy(struct mutex *lock)
+{
+ DEBUG_WARN_ON(mutex_is_locked(lock));
+ lock->magic = NULL;
+}
+
+EXPORT_SYMBOL_GPL(mutex_destroy);
+
diff --git a/kernel/mutex-debug.h b/kernel/mutex-debug.h
new file mode 100644
index 000000000000..fd384050acb1
--- /dev/null
+++ b/kernel/mutex-debug.h
@@ -0,0 +1,134 @@
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains mutex debugging related internal declarations,
+ * prototypes and inline functions, for the CONFIG_DEBUG_MUTEXES case.
+ * More details are in kernel/mutex-debug.c.
+ */
+
+extern spinlock_t debug_mutex_lock;
+extern struct list_head debug_mutex_held_locks;
+extern int debug_mutex_on;
+
+/*
+ * In the debug case we carry the caller's instruction pointer into
+ * other functions, but we dont want the function argument overhead
+ * in the nondebug case - hence these macros:
+ */
+#define __IP_DECL__ , unsigned long ip
+#define __IP__ , ip
+#define __RET_IP__ , (unsigned long)__builtin_return_address(0)
+
+/*
+ * This must be called with lock->wait_lock held.
+ */
+extern void debug_mutex_set_owner(struct mutex *lock,
+ struct thread_info *new_owner __IP_DECL__);
+
+static inline void debug_mutex_clear_owner(struct mutex *lock)
+{
+ lock->owner = NULL;
+}
+
+extern void debug_mutex_init_waiter(struct mutex_waiter *waiter);
+extern void debug_mutex_wake_waiter(struct mutex *lock,
+ struct mutex_waiter *waiter);
+extern void debug_mutex_free_waiter(struct mutex_waiter *waiter);
+extern void debug_mutex_add_waiter(struct mutex *lock,
+ struct mutex_waiter *waiter,
+ struct thread_info *ti __IP_DECL__);
+extern void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
+ struct thread_info *ti);
+extern void debug_mutex_unlock(struct mutex *lock);
+extern void debug_mutex_init(struct mutex *lock, const char *name);
+
+#define debug_spin_lock(lock) \
+ do { \
+ local_irq_disable(); \
+ if (debug_mutex_on) \
+ spin_lock(lock); \
+ } while (0)
+
+#define debug_spin_unlock(lock) \
+ do { \
+ if (debug_mutex_on) \
+ spin_unlock(lock); \
+ local_irq_enable(); \
+ preempt_check_resched(); \
+ } while (0)
+
+#define debug_spin_lock_save(lock, flags) \
+ do { \
+ local_irq_save(flags); \
+ if (debug_mutex_on) \
+ spin_lock(lock); \
+ } while (0)
+
+#define debug_spin_lock_restore(lock, flags) \
+ do { \
+ if (debug_mutex_on) \
+ spin_unlock(lock); \
+ local_irq_restore(flags); \
+ preempt_check_resched(); \
+ } while (0)
+
+#define spin_lock_mutex(lock) \
+ do { \
+ struct mutex *l = container_of(lock, struct mutex, wait_lock); \
+ \
+ DEBUG_WARN_ON(in_interrupt()); \
+ debug_spin_lock(&debug_mutex_lock); \
+ spin_lock(lock); \
+ DEBUG_WARN_ON(l->magic != l); \
+ } while (0)
+
+#define spin_unlock_mutex(lock) \
+ do { \
+ spin_unlock(lock); \
+ debug_spin_unlock(&debug_mutex_lock); \
+ } while (0)
+
+#define DEBUG_OFF() \
+do { \
+ if (debug_mutex_on) { \
+ debug_mutex_on = 0; \
+ console_verbose(); \
+ if (spin_is_locked(&debug_mutex_lock)) \
+ spin_unlock(&debug_mutex_lock); \
+ } \
+} while (0)
+
+#define DEBUG_BUG() \
+do { \
+ if (debug_mutex_on) { \
+ DEBUG_OFF(); \
+ BUG(); \
+ } \
+} while (0)
+
+#define DEBUG_WARN_ON(c) \
+do { \
+ if (unlikely(c && debug_mutex_on)) { \
+ DEBUG_OFF(); \
+ WARN_ON(1); \
+ } \
+} while (0)
+
+# define DEBUG_BUG_ON(c) \
+do { \
+ if (unlikely(c)) \
+ DEBUG_BUG(); \
+} while (0)
+
+#ifdef CONFIG_SMP
+# define SMP_DEBUG_WARN_ON(c) DEBUG_WARN_ON(c)
+# define SMP_DEBUG_BUG_ON(c) DEBUG_BUG_ON(c)
+#else
+# define SMP_DEBUG_WARN_ON(c) do { } while (0)
+# define SMP_DEBUG_BUG_ON(c) do { } while (0)
+#endif
+
diff --git a/kernel/mutex.c b/kernel/mutex.c
new file mode 100644
index 000000000000..7eb960661441
--- /dev/null
+++ b/kernel/mutex.c
@@ -0,0 +1,325 @@
+/*
+ * kernel/mutex.c
+ *
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * Started by Ingo Molnar:
+ *
+ * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
+ * David Howells for suggestions and improvements.
+ *
+ * Also see Documentation/mutex-design.txt.
+ */
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+
+/*
+ * In the DEBUG case we are using the "NULL fastpath" for mutexes,
+ * which forces all calls into the slowpath:
+ */
+#ifdef CONFIG_DEBUG_MUTEXES
+# include "mutex-debug.h"
+# include <asm-generic/mutex-null.h>
+#else
+# include "mutex.h"
+# include <asm/mutex.h>
+#endif
+
+/***
+ * mutex_init - initialize the mutex
+ * @lock: the mutex to be initialized
+ *
+ * Initialize the mutex to unlocked state.
+ *
+ * It is not allowed to initialize an already locked mutex.
+ */
+void fastcall __mutex_init(struct mutex *lock, const char *name)
+{
+ atomic_set(&lock->count, 1);
+ spin_lock_init(&lock->wait_lock);
+ INIT_LIST_HEAD(&lock->wait_list);
+
+ debug_mutex_init(lock, name);
+}
+
+EXPORT_SYMBOL(__mutex_init);
+
+/*
+ * We split the mutex lock/unlock logic into separate fastpath and
+ * slowpath functions, to reduce the register pressure on the fastpath.
+ * We also put the fastpath first in the kernel image, to make sure the
+ * branch is predicted by the CPU as default-untaken.
+ */
+static void fastcall noinline __sched
+__mutex_lock_slowpath(atomic_t *lock_count __IP_DECL__);
+
+/***
+ * mutex_lock - acquire the mutex
+ * @lock: the mutex to be acquired
+ *
+ * Lock the mutex exclusively for this task. If the mutex is not
+ * available right now, it will sleep until it can get it.
+ *
+ * The mutex must later on be released by the same task that
+ * acquired it. Recursive locking is not allowed. The task
+ * may not exit without first unlocking the mutex. Also, kernel
+ * memory where the mutex resides mutex must not be freed with
+ * the mutex still locked. The mutex must first be initialized
+ * (or statically defined) before it can be locked. memset()-ing
+ * the mutex to 0 is not allowed.
+ *
+ * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging
+ * checks that will enforce the restrictions and will also do
+ * deadlock debugging. )
+ *
+ * This function is similar to (but not equivalent to) down().
+ */
+void fastcall __sched mutex_lock(struct mutex *lock)
+{
+ /*
+ * The locking fastpath is the 1->0 transition from
+ * 'unlocked' into 'locked' state.
+ *
+ * NOTE: if asm/mutex.h is included, then some architectures
+ * rely on mutex_lock() having _no other code_ here but this
+ * fastpath. That allows the assembly fastpath to do
+ * tail-merging optimizations. (If you want to put testcode
+ * here, do it under #ifndef CONFIG_MUTEX_DEBUG.)
+ */
+ __mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
+}
+
+EXPORT_SYMBOL(mutex_lock);
+
+static void fastcall noinline __sched
+__mutex_unlock_slowpath(atomic_t *lock_count __IP_DECL__);
+
+/***
+ * mutex_unlock - release the mutex
+ * @lock: the mutex to be released
+ *
+ * Unlock a mutex that has been locked by this task previously.
+ *
+ * This function must not be used in interrupt context. Unlocking
+ * of a not locked mutex is not allowed.
+ *
+ * This function is similar to (but not equivalent to) up().
+ */
+void fastcall __sched mutex_unlock(struct mutex *lock)
+{
+ /*
+ * The unlocking fastpath is the 0->1 transition from 'locked'
+ * into 'unlocked' state:
+ *
+ * NOTE: no other code must be here - see mutex_lock() .
+ */
+ __mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
+}
+
+EXPORT_SYMBOL(mutex_unlock);
+
+/*
+ * Lock a mutex (possibly interruptible), slowpath:
+ */
+static inline int __sched
+__mutex_lock_common(struct mutex *lock, long state __IP_DECL__)
+{
+ struct task_struct *task = current;
+ struct mutex_waiter waiter;
+ unsigned int old_val;
+
+ debug_mutex_init_waiter(&waiter);
+
+ spin_lock_mutex(&lock->wait_lock);
+
+ debug_mutex_add_waiter(lock, &waiter, task->thread_info, ip);
+
+ /* add waiting tasks to the end of the waitqueue (FIFO): */
+ list_add_tail(&waiter.list, &lock->wait_list);
+ waiter.task = task;
+
+ for (;;) {
+ /*
+ * Lets try to take the lock again - this is needed even if
+ * we get here for the first time (shortly after failing to
+ * acquire the lock), to make sure that we get a wakeup once
+ * it's unlocked. Later on, if we sleep, this is the
+ * operation that gives us the lock. We xchg it to -1, so
+ * that when we release the lock, we properly wake up the
+ * other waiters:
+ */
+ old_val = atomic_xchg(&lock->count, -1);
+ if (old_val == 1)
+ break;
+
+ /*
+ * got a signal? (This code gets eliminated in the
+ * TASK_UNINTERRUPTIBLE case.)
+ */
+ if (unlikely(state == TASK_INTERRUPTIBLE &&
+ signal_pending(task))) {
+ mutex_remove_waiter(lock, &waiter, task->thread_info);
+ spin_unlock_mutex(&lock->wait_lock);
+
+ debug_mutex_free_waiter(&waiter);
+ return -EINTR;
+ }
+ __set_task_state(task, state);
+
+ /* didnt get the lock, go to sleep: */
+ spin_unlock_mutex(&lock->wait_lock);
+ schedule();
+ spin_lock_mutex(&lock->wait_lock);
+ }
+
+ /* got the lock - rejoice! */
+ mutex_remove_waiter(lock, &waiter, task->thread_info);
+ debug_mutex_set_owner(lock, task->thread_info __IP__);
+
+ /* set it to 0 if there are no waiters left: */
+ if (likely(list_empty(&lock->wait_list)))
+ atomic_set(&lock->count, 0);
+
+ spin_unlock_mutex(&lock->wait_lock);
+
+ debug_mutex_free_waiter(&waiter);
+
+ DEBUG_WARN_ON(list_empty(&lock->held_list));
+ DEBUG_WARN_ON(lock->owner != task->thread_info);
+
+ return 0;
+}
+
+static void fastcall noinline __sched
+__mutex_lock_slowpath(atomic_t *lock_count __IP_DECL__)
+{
+ struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+ __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE __IP__);
+}
+
+/*
+ * Release the lock, slowpath:
+ */
+static fastcall noinline void
+__mutex_unlock_slowpath(atomic_t *lock_count __IP_DECL__)
+{
+ struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+ DEBUG_WARN_ON(lock->owner != current_thread_info());
+
+ spin_lock_mutex(&lock->wait_lock);
+
+ /*
+ * some architectures leave the lock unlocked in the fastpath failure
+ * case, others need to leave it locked. In the later case we have to
+ * unlock it here
+ */
+ if (__mutex_slowpath_needs_to_unlock())
+ atomic_set(&lock->count, 1);
+
+ debug_mutex_unlock(lock);
+
+ if (!list_empty(&lock->wait_list)) {
+ /* get the first entry from the wait-list: */
+ struct mutex_waiter *waiter =
+ list_entry(lock->wait_list.next,
+ struct mutex_waiter, list);
+
+ debug_mutex_wake_waiter(lock, waiter);
+
+ wake_up_process(waiter->task);
+ }
+
+ debug_mutex_clear_owner(lock);
+
+ spin_unlock_mutex(&lock->wait_lock);
+}
+
+/*
+ * Here come the less common (and hence less performance-critical) APIs:
+ * mutex_lock_interruptible() and mutex_trylock().
+ */
+static int fastcall noinline __sched
+__mutex_lock_interruptible_slowpath(atomic_t *lock_count __IP_DECL__);
+
+/***
+ * mutex_lock_interruptible - acquire the mutex, interruptable
+ * @lock: the mutex to be acquired
+ *
+ * Lock the mutex like mutex_lock(), and return 0 if the mutex has
+ * been acquired or sleep until the mutex becomes available. If a
+ * signal arrives while waiting for the lock then this function
+ * returns -EINTR.
+ *
+ * This function is similar to (but not equivalent to) down_interruptible().
+ */
+int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
+{
+ /* NOTE: no other code must be here - see mutex_lock() */
+ return __mutex_fastpath_lock_retval
+ (&lock->count, __mutex_lock_interruptible_slowpath);
+}
+
+EXPORT_SYMBOL(mutex_lock_interruptible);
+
+static int fastcall noinline __sched
+__mutex_lock_interruptible_slowpath(atomic_t *lock_count __IP_DECL__)
+{
+ struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+ return __mutex_lock_common(lock, TASK_INTERRUPTIBLE __IP__);
+}
+
+/*
+ * Spinlock based trylock, we take the spinlock and check whether we
+ * can get the lock:
+ */
+static inline int __mutex_trylock_slowpath(atomic_t *lock_count)
+{
+ struct mutex *lock = container_of(lock_count, struct mutex, count);
+ int prev;
+
+ spin_lock_mutex(&lock->wait_lock);
+
+ prev = atomic_xchg(&lock->count, -1);
+ if (likely(prev == 1))
+ debug_mutex_set_owner(lock, current_thread_info() __RET_IP__);
+ /* Set it back to 0 if there are no waiters: */
+ if (likely(list_empty(&lock->wait_list)))
+ atomic_set(&lock->count, 0);
+
+ spin_unlock_mutex(&lock->wait_lock);
+
+ return prev == 1;
+}
+
+/***
+ * mutex_trylock - try acquire the mutex, without waiting
+ * @lock: the mutex to be acquired
+ *
+ * Try to acquire the mutex atomically. Returns 1 if the mutex
+ * has been acquired successfully, and 0 on contention.
+ *
+ * NOTE: this function follows the spin_trylock() convention, so
+ * it is negated to the down_trylock() return values! Be careful
+ * about this when converting semaphore users to mutexes.
+ *
+ * This function must not be used in interrupt context. The
+ * mutex must be released by the same task that acquired it.
+ */
+int fastcall mutex_trylock(struct mutex *lock)
+{
+ return __mutex_fastpath_trylock(&lock->count,
+ __mutex_trylock_slowpath);
+}
+
+EXPORT_SYMBOL(mutex_trylock);
+
+
+
diff --git a/kernel/mutex.h b/kernel/mutex.h
new file mode 100644
index 000000000000..00fe84e7b672
--- /dev/null
+++ b/kernel/mutex.h
@@ -0,0 +1,35 @@
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains mutex debugging related internal prototypes, for the
+ * !CONFIG_DEBUG_MUTEXES case. Most of them are NOPs:
+ */
+
+#define spin_lock_mutex(lock) spin_lock(lock)
+#define spin_unlock_mutex(lock) spin_unlock(lock)
+#define mutex_remove_waiter(lock, waiter, ti) \
+ __list_del((waiter)->list.prev, (waiter)->list.next)
+
+#define DEBUG_WARN_ON(c) do { } while (0)
+#define debug_mutex_set_owner(lock, new_owner) do { } while (0)
+#define debug_mutex_clear_owner(lock) do { } while (0)
+#define debug_mutex_init_waiter(waiter) do { } while (0)
+#define debug_mutex_wake_waiter(lock, waiter) do { } while (0)
+#define debug_mutex_free_waiter(waiter) do { } while (0)
+#define debug_mutex_add_waiter(lock, waiter, ti, ip) do { } while (0)
+#define debug_mutex_unlock(lock) do { } while (0)
+#define debug_mutex_init(lock, name) do { } while (0)
+
+/*
+ * Return-address parameters/declarations. They are very useful for
+ * debugging, but add overhead in the !DEBUG case - so we go the
+ * trouble of using this not too elegant but zero-cost solution:
+ */
+#define __IP_DECL__
+#define __IP__
+#define __RET_IP__
+
diff --git a/kernel/sched.c b/kernel/sched.c
index 92733091154c..34a945bcc022 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4386,6 +4386,7 @@ void show_state(void)
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
+ mutex_debug_show_all_locks();
}
/**