Browse Source

timerfd use waitqueue lock ...

The timerfd was using the unlocked waitqueue operations, but it was
using a different lock, so poll_wait() would race with it.

This makes timerfd directly use the waitqueue lock.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
master
Davide Libenzi 15 years ago
committed by Linus Torvalds
parent
commit
18963c01b8
  1. 24
      fs/timerfd.c

24
fs/timerfd.c

@ -24,7 +24,6 @@
struct timerfd_ctx {
struct hrtimer tmr;
ktime_t tintv;
spinlock_t lock;
wait_queue_head_t wqh;
int expired;
};
@ -39,10 +38,10 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx, tmr);
unsigned long flags;
spin_lock_irqsave(&ctx->lock, flags);
spin_lock_irqsave(&ctx->wqh.lock, flags);
ctx->expired = 1;
wake_up_locked(&ctx->wqh);
spin_unlock_irqrestore(&ctx->lock, flags);
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
return HRTIMER_NORESTART;
}
@ -83,10 +82,10 @@ static unsigned int timerfd_poll(struct file *file, poll_table *wait)
poll_wait(file, &ctx->wqh, wait);
spin_lock_irqsave(&ctx->lock, flags);
spin_lock_irqsave(&ctx->wqh.lock, flags);
if (ctx->expired)
events |= POLLIN;
spin_unlock_irqrestore(&ctx->lock, flags);
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
return events;
}
@ -101,7 +100,7 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
if (count < sizeof(ticks))
return -EINVAL;
spin_lock_irq(&ctx->lock);
spin_lock_irq(&ctx->wqh.lock);
res = -EAGAIN;
if (!ctx->expired && !(file->f_flags & O_NONBLOCK)) {
__add_wait_queue(&ctx->wqh, &wait);
@ -115,9 +114,9 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
res = -ERESTARTSYS;
break;
}
spin_unlock_irq(&ctx->lock);
spin_unlock_irq(&ctx->wqh.lock);
schedule();
spin_lock_irq(&ctx->lock);
spin_lock_irq(&ctx->wqh.lock);
}
__remove_wait_queue(&ctx->wqh, &wait);
__set_current_state(TASK_RUNNING);
@ -139,7 +138,7 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
} else
ticks = 1;
}
spin_unlock_irq(&ctx->lock);
spin_unlock_irq(&ctx->wqh.lock);
if (ticks)
res = put_user(ticks, buf) ? -EFAULT: sizeof(ticks);
return res;
@ -176,7 +175,6 @@ asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
return -ENOMEM;
init_waitqueue_head(&ctx->wqh);
spin_lock_init(&ctx->lock);
timerfd_setup(ctx, clockid, flags, &ktmr);
@ -202,10 +200,10 @@ asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
* it to the new values.
*/
for (;;) {
spin_lock_irq(&ctx->lock);
spin_lock_irq(&ctx->wqh.lock);
if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
break;
spin_unlock_irq(&ctx->lock);
spin_unlock_irq(&ctx->wqh.lock);
cpu_relax();
}
/*
@ -213,7 +211,7 @@ asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
*/
timerfd_setup(ctx, clockid, flags, &ktmr);
spin_unlock_irq(&ctx->lock);
spin_unlock_irq(&ctx->wqh.lock);
fput(file);
}

Loading…
Cancel
Save