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authorThomas Gleixner <tglx@linutronix.de>2006-09-08 09:47:15 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-08 10:22:50 -0700
commitc5780e976e19faff345fcef4a01db87108b51a44 (patch)
tree1e75fc4cd3765beb575fb3196a477d97ed1905a4
parent3a459756810912d2c2bf188cef566af255936b4d (diff)
[PATCH] Use the correct restart option for futex_lock_pi
The current implementation of futex_lock_pi returns -ERESTART_RESTARTBLOCK in case that the lock operation has been interrupted by a signal. This results in a return of -EINTR to userspace in case there is an handler for the signal. This is wrong, because userspace expects that the lock function does not return in any case of signal delivery. This was not caught by my insufficient test case, but triggered a nasty userspace problem in an high load application scenario. Unfortunately also glibc does not check for this invalid return value. Using -ERSTARTNOINTR makes sure, that the interrupted syscall is restarted. The restart block related code can be safely removed, as the possible timeout argument is an absolute time value. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/futex.c84
1 files changed, 11 insertions, 73 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index b9b8aea5389..9d260e838cf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1120,9 +1120,10 @@ static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
* if there are waiters then it will block, it does PI, etc. (Due to
* races the kernel might see a 0 value of the futex too.)
*/
-static int do_futex_lock_pi(u32 __user *uaddr, int detect, int trylock,
- struct hrtimer_sleeper *to)
+static int futex_lock_pi(u32 __user *uaddr, int detect, unsigned long sec,
+ long nsec, int trylock)
{
+ struct hrtimer_sleeper timeout, *to = NULL;
struct task_struct *curr = current;
struct futex_hash_bucket *hb;
u32 uval, newval, curval;
@@ -1132,6 +1133,13 @@ static int do_futex_lock_pi(u32 __user *uaddr, int detect, int trylock,
if (refill_pi_state_cache())
return -ENOMEM;
+ if (sec != MAX_SCHEDULE_TIMEOUT) {
+ to = &timeout;
+ hrtimer_init(&to->timer, CLOCK_REALTIME, HRTIMER_ABS);
+ hrtimer_init_sleeper(to, current);
+ to->timer.expires = ktime_set(sec, nsec);
+ }
+
q.pi_state = NULL;
retry:
down_read(&curr->mm->mmap_sem);
@@ -1307,7 +1315,7 @@ static int do_futex_lock_pi(u32 __user *uaddr, int detect, int trylock,
if (!detect && ret == -EDEADLK && 0)
force_sig(SIGKILL, current);
- return ret;
+ return ret != -EINTR ? ret : -ERESTARTNOINTR;
out_unlock_release_sem:
queue_unlock(&q, hb);
@@ -1342,76 +1350,6 @@ static int do_futex_lock_pi(u32 __user *uaddr, int detect, int trylock,
}
/*
- * Restart handler
- */
-static long futex_lock_pi_restart(struct restart_block *restart)
-{
- struct hrtimer_sleeper timeout, *to = NULL;
- int ret;
-
- restart->fn = do_no_restart_syscall;
-
- if (restart->arg2 || restart->arg3) {
- to = &timeout;
- hrtimer_init(&to->timer, CLOCK_REALTIME, HRTIMER_ABS);
- hrtimer_init_sleeper(to, current);
- to->timer.expires.tv64 = ((u64)restart->arg1 << 32) |
- (u64) restart->arg0;
- }
-
- pr_debug("lock_pi restart: %p, %d (%d)\n",
- (u32 __user *)restart->arg0, current->pid);
-
- ret = do_futex_lock_pi((u32 __user *)restart->arg0, restart->arg1,
- 0, to);
-
- if (ret != -EINTR)
- return ret;
-
- restart->fn = futex_lock_pi_restart;
-
- /* The other values are filled in */
- return -ERESTART_RESTARTBLOCK;
-}
-
-/*
- * Called from the syscall entry below.
- */
-static int futex_lock_pi(u32 __user *uaddr, int detect, unsigned long sec,
- long nsec, int trylock)
-{
- struct hrtimer_sleeper timeout, *to = NULL;
- struct restart_block *restart;
- int ret;
-
- if (sec != MAX_SCHEDULE_TIMEOUT) {
- to = &timeout;
- hrtimer_init(&to->timer, CLOCK_REALTIME, HRTIMER_ABS);
- hrtimer_init_sleeper(to, current);
- to->timer.expires = ktime_set(sec, nsec);
- }
-
- ret = do_futex_lock_pi(uaddr, detect, trylock, to);
-
- if (ret != -EINTR)
- return ret;
-
- pr_debug("lock_pi interrupted: %p, %d (%d)\n", uaddr, current->pid);
-
- restart = &current_thread_info()->restart_block;
- restart->fn = futex_lock_pi_restart;
- restart->arg0 = (unsigned long) uaddr;
- restart->arg1 = detect;
- if (to) {
- restart->arg2 = to->timer.expires.tv64 & 0xFFFFFFFF;
- restart->arg3 = to->timer.expires.tv64 >> 32;
- } else
- restart->arg2 = restart->arg3 = 0;
-
- return -ERESTART_RESTARTBLOCK;
-}
-
-/*
* Userspace attempted a TID -> 0 atomic transition, and failed.
* This is the in-kernel slowpath: we look up the PI state (if any),
* and do the rt-mutex unlock.