All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Jens Axboe <axboe@kernel.dk>, "Rafael J. Wysocki" <rjw@sisk.pl>,
	Linux-pm mailing list <linux-pm@vger.kernel.org>,
	Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: Bug in disk event polling
Date: Fri, 10 Feb 2012 13:12:55 -0800	[thread overview]
Message-ID: <20120210211255.GK19392@google.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1202101557280.1281-100000@iolanthe.rowland.org>

Hello, Alan.

On Fri, Feb 10, 2012 at 04:03:51PM -0500, Alan Stern wrote:
> None of those resets above should have occurred.  They are the result
> of trying to recover from the failure of a TEST UNIT READY command.

Thanks for the log.  Yeah, I was just thinking about libata and
wondering why it would break that badly.

> > > I have verified that changing all occurrences of system_nrt_wq in 
> > > block/genhd.c to system_freezable_wq fixes the bug.  However this may 
> > > not be the way you want to solve it; you may prefer to have a freezable 
> > > non-reentrant work queue.
> > 
> > Please feel free to send out a patch to fix the issue. :)
> 
> Is there a real reason for using system_nrt_wq?  Are you okay with just
> switching over to system_freezable_wq?

I think it should be nrt.  It assumes that no one else is running it
concurrently; otherwise, multiple CPUs could jump into
disk->fops->check_events() concurrently which can be pretty ugly.

Thanks.

-- 
tejun

  reply	other threads:[~2012-02-10 21:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-10 20:31 Bug in disk event polling Alan Stern
2012-02-10 20:46 ` Tejun Heo
2012-02-10 21:03   ` Alan Stern
2012-02-10 21:12     ` Tejun Heo [this message]
2012-02-10 21:44       ` Alan Stern
2012-02-11  0:23         ` Tejun Heo
2012-02-12 17:48           ` Alan Stern
2012-02-12 21:26             ` Rafael J. Wysocki
2012-02-12 22:02               ` Alan Stern
2012-02-13 17:30             ` Tejun Heo

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=20120210211255.GK19392@google.com \
    --to=tj@kernel.org \
    --cc=axboe@kernel.dk \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=rjw@sisk.pl \
    --cc=stern@rowland.harvard.edu \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.