linux-kernel - Re: [PATCH 1/6] fuse: Kill fasync only if interrupt is queued in queue

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Date:   Wed, 7 Nov 2018 13:45:26 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] fuse: Kill fasync only if interrupt is queued in queue_interrupt()

On Tue, Nov 6, 2018 at 10:30 AM, Kirill Tkhai <ktkhai@...tuozzo.com> wrote:
> We should sent signal only in case of interrupt is really queued.
> Not a real problem, but this makes the code clearer and intuitive.
>
> Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
> ---
>  fs/fuse/dev.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index fb2530ed84b3..7705f75c77a3 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -468,6 +468,8 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
>
>  static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
>  {
> +       bool kill = false;
> +
>         spin_lock(&fiq->waitq.lock);
>         if (test_bit(FR_FINISHED, &req->flags)) {
>                 spin_unlock(&fiq->waitq.lock);
> @@ -476,9 +478,11 @@ static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
>         if (list_empty(&req->intr_entry)) {
>                 list_add_tail(&req->intr_entry, &fiq->interrupts);
>                 wake_up_locked(&fiq->waitq);
> +               kill = true;
>         }
>         spin_unlock(&fiq->waitq.lock);
> -       kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
> +       if (kill)
> +               kill_fasync(&fiq->fasync, SIGIO, POLL_IN);

All other cases just do the kill_fasync() inside the fiq->waitq.lock
locked region.  That seems the simpler and more readable solution to
this.

Thanks,
Miklos