The patch titled
timerfd: use waitqueue lock
has been added to the -mm tree. Its filename is
timerfd-use-waitqueue-lock.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: timerfd: use waitqueue lock
From: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
The timerfd was using the unlocked waitqueue operations, but it was using a
different lock, so poll_wait() would race with it. This patch makes
timerfd directly use the waitqueue lock.
Signed-off-by: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Cc: Davi Arnaut <davi@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/timerfd.c | 24 +++++++++++-------------
1 files changed, 11 insertions(+), 13 deletions(-)
diff -puN fs/timerfd.c~timerfd-use-waitqueue-lock fs/timerfd.c
--- a/fs/timerfd.c~timerfd-use-waitqueue-lock
+++ a/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_tmrp
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
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
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
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
} 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
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
* 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
*/
timerfd_setup(ctx, clockid, flags, &ktmr);
- spin_unlock_irq(&ctx->lock);
+ spin_unlock_irq(&ctx->wqh.lock);
fput(file);
}
_
Patches currently in -mm which might be from davidel@xxxxxxxxxxxxxxx are
origin.patch
x86_64-fix-oprofile-smp.patch
eventfd-use-waitqueue-lock.patch
timerfd-use-waitqueue-lock.patch
-
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