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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-16 02:28:30 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-16 02:28:30 +0100 |
commit | 0586bed3e8563c2eb89bc7256e30ce633ae06cfb (patch) | |
tree | 7a59610f45f7222f25b3212c53fa28636bb4427c /kernel/futex.c | |
parent | Merge branch 'core-futexes-for-linus' of git://git.kernel.org/pub/scm/linux/k... (diff) | |
parent | rtmutex: tester: Remove the remaining BKL leftovers (diff) | |
download | linux-0586bed3e8563c2eb89bc7256e30ce633ae06cfb.tar.xz linux-0586bed3e8563c2eb89bc7256e30ce633ae06cfb.zip |
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
rtmutex: tester: Remove the remaining BKL leftovers
lockdep/timers: Explain in detail the locking problems del_timer_sync() may cause
rtmutex: Simplify PI algorithm and make highest prio task get lock
rwsem: Remove redundant asmregparm annotation
rwsem: Move duplicate function prototypes to linux/rwsem.h
rwsem: Unify the duplicate rwsem_is_locked() inlines
rwsem: Move duplicate init macros and functions to linux/rwsem.h
rwsem: Move duplicate struct rwsem declaration to linux/rwsem.h
x86: Cleanup rwsem_count_t typedef
rwsem: Cleanup includes
locking: Remove deprecated lock initializers
cred: Replace deprecated spinlock initialization
kthread: Replace deprecated spinlock initialization
xtensa: Replace deprecated spinlock initialization
um: Replace deprecated spinlock initialization
sparc: Replace deprecated spinlock initialization
mips: Replace deprecated spinlock initialization
cris: Replace deprecated spinlock initialization
alpha: Replace deprecated spinlock initialization
rtmutex-tester: Remove BKL tests
Diffstat (limited to 'kernel/futex.c')
-rw-r--r-- | kernel/futex.c | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index e9251d934f7d..bda415715382 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1555,10 +1555,10 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, /* * We are here either because we stole the rtmutex from the - * pending owner or we are the pending owner which failed to - * get the rtmutex. We have to replace the pending owner TID - * in the user space variable. This must be atomic as we have - * to preserve the owner died bit here. + * previous highest priority waiter or we are the highest priority + * waiter but failed to get the rtmutex the first time. + * We have to replace the newowner TID in the user space variable. + * This must be atomic as we have to preserve the owner died bit here. * * Note: We write the user space value _before_ changing the pi_state * because we can fault here. Imagine swapped out pages or a fork @@ -1605,8 +1605,8 @@ retry: /* * To handle the page fault we need to drop the hash bucket - * lock here. That gives the other task (either the pending - * owner itself or the task which stole the rtmutex) the + * lock here. That gives the other task (either the highest priority + * waiter itself or the task which stole the rtmutex) the * chance to try the fixup of the pi_state. So once we are * back from handling the fault we need to check the pi_state * after reacquiring the hash bucket lock and before trying to @@ -1682,18 +1682,20 @@ static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked) /* * pi_state is incorrect, some other task did a lock steal and * we returned due to timeout or signal without taking the - * rt_mutex. Too late. We can access the rt_mutex_owner without - * locking, as the other task is now blocked on the hash bucket - * lock. Fix the state up. + * rt_mutex. Too late. */ + raw_spin_lock(&q->pi_state->pi_mutex.wait_lock); owner = rt_mutex_owner(&q->pi_state->pi_mutex); + if (!owner) + owner = rt_mutex_next_owner(&q->pi_state->pi_mutex); + raw_spin_unlock(&q->pi_state->pi_mutex.wait_lock); ret = fixup_pi_state_owner(uaddr, q, owner); goto out; } /* * Paranoia check. If we did not take the lock, then we should not be - * the owner, nor the pending owner, of the rt_mutex. + * the owner of the rt_mutex. */ if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p " |