From: Mike Snitzer <snitzer@redhat.com>
To: Tahsin Erdogan <tahsin@google.com>
Cc: Alasdair Kergon <agk@redhat.com>,
dm-devel@redhat.com, Shaohua Li <shli@kernel.org>,
linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: dm: free io_barrier after blk_cleanup_queue call
Date: Mon, 10 Oct 2016 09:25:42 -0400 [thread overview]
Message-ID: <20161010132542.GA17958@redhat.com> (raw)
In-Reply-To: <1476102919-25112-1-git-send-email-tahsin@google.com>
On Mon, Oct 10 2016 at 8:35am -0400,
Tahsin Erdogan <tahsin@google.com> wrote:
> dm_old_request_fn() has paths that access md->io_barrier. The party
> destroying io_barrier should ensure that no future execution
> of dm_old_request_fn() is possible. Move destruction to below
> blk_cleanup_queue() to ensure this.
I have to believe this was born out of code inspection rather than
actual need (due to crash, etc)?
The cleanup order isn't relevant. The reference counting of a DM device
governs whether a DM device (and its associated 'struct mapped_device')
can be destroyed. Please have a look at __dm_destroy, particularly:
* No one should increment the reference count of the mapped_device,
* after the mapped_device state becomes DMF_FREEING.
Mike
next prev parent reply other threads:[~2016-10-10 13:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-10 12:35 [PATCH] dm: free io_barrier after blk_cleanup_queue call Tahsin Erdogan
2016-10-10 13:25 ` Mike Snitzer [this message]
2016-10-10 14:52 ` Tahsin Erdogan
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