All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Rabin Vincent <rabin@rab.in>, Jens Axboe <axboe@fb.com>,
	Jan Kara <jack@suse.cz>, Al Viro <viro@zeniv.linux.org.uk>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] bdev: fix NULL pointer dereference in sync()/close() race
Date: Mon, 29 Aug 2016 16:54:39 -0400	[thread overview]
Message-ID: <20160829205439.GG28713@mtj.duckdns.org> (raw)
In-Reply-To: <5c8ff17a-27ba-0987-401d-9eeeb66b52f2@oracle.com>

Hello,

On Mon, Aug 29, 2016 at 10:49:57PM +0200, Vegard Nossum wrote:
> That didn't work at all. I guess bd_acquire() would just do a bdgrab()
> and not touch ->bd_holders, whereas blkdev_get() would increment

Yeah, bdev has two different refs - one for bdev struct itself and the
other for the actual accessors.

> bd_holders and therefore prevent __blkdev_put() from freeing the block
> device? Too confusing...

I think you'll need to do the actual blkdev_get or one of its
variants.

Thanks.

-- 
tejun

  reply	other threads:[~2016-08-29 20:54 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-27  7:07 [PATCH] bdev: fix NULL pointer dereference in sync()/close() race Vegard Nossum
2016-08-27  9:03 ` Rabin Vincent
2016-08-27  9:30   ` Vegard Nossum
2016-08-29 19:55     ` Tejun Heo
2016-08-29 20:49       ` Vegard Nossum
2016-08-29 20:54         ` Tejun Heo [this message]
2016-08-29 21:33       ` Vegard Nossum
2016-08-29 23:49         ` 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=20160829205439.GG28713@mtj.duckdns.org \
    --to=tj@kernel.org \
    --cc=axboe@fb.com \
    --cc=jack@suse.cz \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rabin@rab.in \
    --cc=stable@vger.kernel.org \
    --cc=vegard.nossum@oracle.com \
    --cc=viro@zeniv.linux.org.uk \
    /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.