From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takahiro Yasui Subject: [RFC][PATCH 0/3] dm-raid1: fix deadlock at suspend after suspend was interrupted Date: Tue, 19 Jan 2010 15:40:55 -0500 Message-ID: <4B5618D7.4050202@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids Hi, This is a patch set to fix deadlock on suspending of mirror device. ISSUE ===== Suspend procedure on a dm-mirror device could cause deadlock on recovery_count semaphore. When mirror_presuspend is called, recovery_count semaphore is acquired in dm_rh_stop_recovery() to stop recovery routine, but when an signal is caught in dm_wait_for_completion() or an error occurred in in dm_suspend(), the suspend process is interrupted without releasing recovery_count semaphore of a mirror device. This means that another suspend is executed, and then the suspend process gets stuck at dm_rh_stop_recovery(). When suspend procedure is interrupted, the device should work properly since the status of the device is not "suspended." SOLUTION ======== Introduce a target handler, cancel_presuspend, to cancel status changes done by a target specific presuspend handler. PATCH SET ========= 1/3: dm: introduce cancel_presuspend framework 2/3: dm-raid1: add cancel_presuspend function 3/3: dm-delay: add cancel_presuspend function I appreciate your comments. Thanks, -- Takahiro Yasui Hitachi Computer Products (America), Inc.