From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH v3 1/2] scsi: fix race between simultaneous decrements of ->host_failed Date: Thu, 2 Jun 2016 09:20:51 -0700 Message-ID: <20160602162051.GA26699@kroah.com> References: <1464856958-30647-1-git-send-email-fangwei1@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1464856958-30647-1-git-send-email-fangwei1@huawei.com> Sender: linux-doc-owner@vger.kernel.org To: Wei Fang Cc: tj@kernel.org, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, corbet@lwn.net, hch@infradead.org, dan.j.williams@intel.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org, stable@vger.kernel.org List-Id: linux-ide@vger.kernel.org On Thu, Jun 02, 2016 at 04:42:37PM +0800, Wei Fang wrote: > sas_ata_strategy_handler() adds the works of the ata error handler > to system_unbound_wq. This workqueue asynchronously runs work items, > so the ata error handler will be performed concurrently on different > CPUs. In this case, ->host_failed will be decreased simultaneously in > scsi_eh_finish_cmd() on different CPUs, and become abnormal. > > It will lead to permanently inequal between ->host_failed and > ->host_busy, and scsi error handler thread won't become running. > IO errors after that won't be handled forever. > > Since all scmds must have been handled in the strategy handle, just > remove the decrement in scsi_eh_finish_cmd() and zero ->host_busy > after the strategy handle to fix this race. > > This fixes the problem introduced in > commit 50824d6c5657 ("[SCSI] libsas: async ata-eh"). > > Signed-off-by: Wei Fang This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read Documentation/stable_kernel_rules.txt for how to do this properly.