On Fri, 9 Apr 2010, Michal Nazarewicz wrote:
> This patch modifies the fs/timerfd.c to use the newly created
> wait_event_interruptible_locked_irq() macro. This replaces an open
> code implementation with a single macro call.
And thereby breaks the code. :(
> Signed-off-by: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> fs/timerfd.c | 22 ++--------------------
> 1 files changed, 2 insertions(+), 20 deletions(-)
>
> diff --git a/fs/timerfd.c b/fs/timerfd.c
> index 1bfc95a..4d2c371 100644
> --- a/fs/timerfd.c
> +++ b/fs/timerfd.c
> @@ -109,31 +109,13 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
> struct timerfd_ctx *ctx = file->private_data;
> ssize_t res;
> u64 ticks = 0;
> - DECLARE_WAITQUEUE(wait, current);
>
> if (count < sizeof(ticks))
> return -EINVAL;
> spin_lock_irq(&ctx->wqh.lock);
> res = -EAGAIN;
> - if (!ctx->ticks && !(file->f_flags & O_NONBLOCK)) {
> - __add_wait_queue(&ctx->wqh, &wait);
> - for (res = 0;;) {
> - set_current_state(TASK_INTERRUPTIBLE);
> - if (ctx->ticks) {
> - res = 0;
> - break;
> - }
> - if (signal_pending(current)) {
> - res = -ERESTARTSYS;
> - break;
> - }
> - spin_unlock_irq(&ctx->wqh.lock);
> - schedule();
> - spin_lock_irq(&ctx->wqh.lock);
> - }
> - __remove_wait_queue(&ctx->wqh, &wait);
> - __set_current_state(TASK_RUNNING);
> - }
> + if (!(file->f_flags & O_NONBLOCK))
> + wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks);
With this change we return -EAGAIN instead of -ERESTARTSYS when the
wait got interrupted by a signal. That means instead of restarting the
syscall we return -EAGAIN to user space.
You need to return that information from wait_event.....().
Thanks,
tglx
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