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Merge master.kernel.org:/pub/scm/linux/kernel/git/mingo/mutex-2.6

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This commit is contained in:
Linus Torvalds
2006-01-09 17:31:38 -08:00
parent a457aa6c2b 11b751ae8c
commit 80c0531514
198 changed files with 2754 additions and 649 deletions
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3
kernel/Makefile
View File

@ -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

10
kernel/cpuset.c
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@ -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();

5
kernel/exit.c
View File

@ -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();

4
kernel/fork.c
View File

@ -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;

464
kernel/mutex-debug.c Normal file
View File

@ -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);

134
kernel/mutex-debug.h Normal file
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@ -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

325
kernel/mutex.c Normal file
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@ -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);

35
kernel/mutex.h Normal file
View File

@ -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__

1
kernel/sched.c
View File

@ -4386,6 +4386,7 @@ void show_state(void)
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
mutex_debug_show_all_locks();
}
/**