linux-block.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Denis Efremov <efremov@linux.com>
To: Tasos Sahanidis <tasos@tasossah.com>, linux-block@vger.kernel.org
Cc: axboe@kernel.dk, jkosina@suse.cz
Subject: Re: [PATCH] floppy: Fix hang in watchdog when disk is ejected
Date: Sun, 19 Sep 2021 01:33:59 +0300	[thread overview]
Message-ID: <92da8abb-4270-83c3-6059-44627eb6b42c@linux.com> (raw)
In-Reply-To: <399e486c-6540-db27-76aa-7a271b061f76@tasossah.com>

Hi,

On 9/3/21 09:47, Tasos Sahanidis wrote:
> When the watchdog detects a disk change, it calls cancel_activity(),
> which in turn tries to cancel the fd_timer delayed work.
> 
> In the above scenario, fd_timer_fn is set to fd_watchdog(), meaning
> it is trying to cancel its own work.
> This results in a hang as cancel_delayed_work_sync() is waiting for the
> watchdog (itself) to return, which never happens.
> 
> This can be reproduced relatively consistently by attempting to read a
> broken floppy, and ejecting it while IO is being attempted and retried.
> 
> To resolve this, this patch calls cancel_delayed_work() instead, which
> cancels the work without waiting for the watchdog to return and finish.
> 
> Before this regression was introduced, the code in this section used
> del_timer(), and not del_timer_sync() to delete the watchdog timer.
> 
> Fixes: 070ad7e793dc ("floppy: convert to delayed work and single-thread wq")
> Signed-off-by: Tasos Sahanidis <tasos@tasossah.com>
> ---
>  drivers/block/floppy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
> index fef79ea52..85464d72d 100644
> --- a/drivers/block/floppy.c
> +++ b/drivers/block/floppy.c
> @@ -1014,7 +1014,7 @@ static DECLARE_DELAYED_WORK(fd_timer, fd_timer_workfn);
>  static void cancel_activity(void)
>  {
>  	do_floppy = NULL;
> -	cancel_delayed_work_sync(&fd_timer);
> +	cancel_delayed_work(&fd_timer);
>  	cancel_work_sync(&floppy_work);
>  }


Sorry for the long response. Applied, thanks!
https://github.com/evdenis/linux-floppy/commit/4258a7afaf3bde4441e844335170ee310ee29392

I will send it to Jens with other fixes.

Regards,
Denis



      reply	other threads:[~2021-09-18 22:34 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-03  6:47 Tasos Sahanidis
2021-09-18 22:33 ` Denis Efremov [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=92da8abb-4270-83c3-6059-44627eb6b42c@linux.com \
    --to=efremov@linux.com \
    --cc=axboe@kernel.dk \
    --cc=jkosina@suse.cz \
    --cc=linux-block@vger.kernel.org \
    --cc=tasos@tasossah.com \
    --subject='Re: [PATCH] floppy: Fix hang in watchdog when disk is ejected' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).