mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-25 02:09:42 +00:00
![Ingo Molnar](/assets/img/avatar_default.png)
The spinlock-debug wait-loop was using loops_per_jiffy to detect too long spinlock waits - but on fast CPUs this led to a way too fast timeout and false messages. The fix is to include a __delay(1) call in the loop, to correctly approximate the intended delay timeout of 1 second. The code assumes that every architecture implements __delay(1) to last around 1/(loops_per_jiffy*HZ) seconds. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
263 lines
5.9 KiB
C
263 lines
5.9 KiB
C
/*
|
|
* Copyright 2005, Red Hat, Inc., Ingo Molnar
|
|
* Released under the General Public License (GPL).
|
|
*
|
|
* This file contains the spinlock/rwlock implementations for
|
|
* DEBUG_SPINLOCK.
|
|
*/
|
|
|
|
#include <linux/config.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/delay.h>
|
|
|
|
static void spin_bug(spinlock_t *lock, const char *msg)
|
|
{
|
|
static long print_once = 1;
|
|
struct task_struct *owner = NULL;
|
|
|
|
if (xchg(&print_once, 0)) {
|
|
if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
|
|
owner = lock->owner;
|
|
printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
|
|
msg, raw_smp_processor_id(),
|
|
current->comm, current->pid);
|
|
printk(KERN_EMERG " lock: %p, .magic: %08x, .owner: %s/%d, "
|
|
".owner_cpu: %d\n",
|
|
lock, lock->magic,
|
|
owner ? owner->comm : "<none>",
|
|
owner ? owner->pid : -1,
|
|
lock->owner_cpu);
|
|
dump_stack();
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* We cannot continue on SMP:
|
|
*/
|
|
// panic("bad locking");
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
|
|
|
|
static inline void debug_spin_lock_before(spinlock_t *lock)
|
|
{
|
|
SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
|
|
SPIN_BUG_ON(lock->owner == current, lock, "recursion");
|
|
SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
|
|
lock, "cpu recursion");
|
|
}
|
|
|
|
static inline void debug_spin_lock_after(spinlock_t *lock)
|
|
{
|
|
lock->owner_cpu = raw_smp_processor_id();
|
|
lock->owner = current;
|
|
}
|
|
|
|
static inline void debug_spin_unlock(spinlock_t *lock)
|
|
{
|
|
SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
|
|
SPIN_BUG_ON(!spin_is_locked(lock), lock, "already unlocked");
|
|
SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
|
|
SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
|
|
lock, "wrong CPU");
|
|
lock->owner = SPINLOCK_OWNER_INIT;
|
|
lock->owner_cpu = -1;
|
|
}
|
|
|
|
static void __spin_lock_debug(spinlock_t *lock)
|
|
{
|
|
int print_once = 1;
|
|
u64 i;
|
|
|
|
for (;;) {
|
|
for (i = 0; i < loops_per_jiffy * HZ; i++) {
|
|
if (__raw_spin_trylock(&lock->raw_lock))
|
|
return;
|
|
__delay(1);
|
|
}
|
|
/* lockup suspected: */
|
|
if (print_once) {
|
|
print_once = 0;
|
|
printk(KERN_EMERG "BUG: spinlock lockup on CPU#%d, "
|
|
"%s/%d, %p\n",
|
|
raw_smp_processor_id(), current->comm,
|
|
current->pid, lock);
|
|
dump_stack();
|
|
}
|
|
}
|
|
}
|
|
|
|
void _raw_spin_lock(spinlock_t *lock)
|
|
{
|
|
debug_spin_lock_before(lock);
|
|
if (unlikely(!__raw_spin_trylock(&lock->raw_lock)))
|
|
__spin_lock_debug(lock);
|
|
debug_spin_lock_after(lock);
|
|
}
|
|
|
|
int _raw_spin_trylock(spinlock_t *lock)
|
|
{
|
|
int ret = __raw_spin_trylock(&lock->raw_lock);
|
|
|
|
if (ret)
|
|
debug_spin_lock_after(lock);
|
|
#ifndef CONFIG_SMP
|
|
/*
|
|
* Must not happen on UP:
|
|
*/
|
|
SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
void _raw_spin_unlock(spinlock_t *lock)
|
|
{
|
|
debug_spin_unlock(lock);
|
|
__raw_spin_unlock(&lock->raw_lock);
|
|
}
|
|
|
|
static void rwlock_bug(rwlock_t *lock, const char *msg)
|
|
{
|
|
static long print_once = 1;
|
|
|
|
if (xchg(&print_once, 0)) {
|
|
printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
|
|
msg, raw_smp_processor_id(), current->comm,
|
|
current->pid, lock);
|
|
dump_stack();
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* We cannot continue on SMP:
|
|
*/
|
|
panic("bad locking");
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
|
|
|
|
static void __read_lock_debug(rwlock_t *lock)
|
|
{
|
|
int print_once = 1;
|
|
u64 i;
|
|
|
|
for (;;) {
|
|
for (i = 0; i < loops_per_jiffy * HZ; i++) {
|
|
if (__raw_read_trylock(&lock->raw_lock))
|
|
return;
|
|
__delay(1);
|
|
}
|
|
/* lockup suspected: */
|
|
if (print_once) {
|
|
print_once = 0;
|
|
printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
|
|
"%s/%d, %p\n",
|
|
raw_smp_processor_id(), current->comm,
|
|
current->pid, lock);
|
|
dump_stack();
|
|
}
|
|
}
|
|
}
|
|
|
|
void _raw_read_lock(rwlock_t *lock)
|
|
{
|
|
RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
|
|
if (unlikely(!__raw_read_trylock(&lock->raw_lock)))
|
|
__read_lock_debug(lock);
|
|
}
|
|
|
|
int _raw_read_trylock(rwlock_t *lock)
|
|
{
|
|
int ret = __raw_read_trylock(&lock->raw_lock);
|
|
|
|
#ifndef CONFIG_SMP
|
|
/*
|
|
* Must not happen on UP:
|
|
*/
|
|
RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
void _raw_read_unlock(rwlock_t *lock)
|
|
{
|
|
RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
|
|
__raw_read_unlock(&lock->raw_lock);
|
|
}
|
|
|
|
static inline void debug_write_lock_before(rwlock_t *lock)
|
|
{
|
|
RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
|
|
RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
|
|
RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
|
|
lock, "cpu recursion");
|
|
}
|
|
|
|
static inline void debug_write_lock_after(rwlock_t *lock)
|
|
{
|
|
lock->owner_cpu = raw_smp_processor_id();
|
|
lock->owner = current;
|
|
}
|
|
|
|
static inline void debug_write_unlock(rwlock_t *lock)
|
|
{
|
|
RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
|
|
RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
|
|
RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
|
|
lock, "wrong CPU");
|
|
lock->owner = SPINLOCK_OWNER_INIT;
|
|
lock->owner_cpu = -1;
|
|
}
|
|
|
|
static void __write_lock_debug(rwlock_t *lock)
|
|
{
|
|
int print_once = 1;
|
|
u64 i;
|
|
|
|
for (;;) {
|
|
for (i = 0; i < loops_per_jiffy * HZ; i++) {
|
|
if (__raw_write_trylock(&lock->raw_lock))
|
|
return;
|
|
__delay(1);
|
|
}
|
|
/* lockup suspected: */
|
|
if (print_once) {
|
|
print_once = 0;
|
|
printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
|
|
"%s/%d, %p\n",
|
|
raw_smp_processor_id(), current->comm,
|
|
current->pid, lock);
|
|
dump_stack();
|
|
}
|
|
}
|
|
}
|
|
|
|
void _raw_write_lock(rwlock_t *lock)
|
|
{
|
|
debug_write_lock_before(lock);
|
|
if (unlikely(!__raw_write_trylock(&lock->raw_lock)))
|
|
__write_lock_debug(lock);
|
|
debug_write_lock_after(lock);
|
|
}
|
|
|
|
int _raw_write_trylock(rwlock_t *lock)
|
|
{
|
|
int ret = __raw_write_trylock(&lock->raw_lock);
|
|
|
|
if (ret)
|
|
debug_write_lock_after(lock);
|
|
#ifndef CONFIG_SMP
|
|
/*
|
|
* Must not happen on UP:
|
|
*/
|
|
RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
void _raw_write_unlock(rwlock_t *lock)
|
|
{
|
|
debug_write_unlock(lock);
|
|
__raw_write_unlock(&lock->raw_lock);
|
|
}
|