From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH 1/3] Remove two cancel_delayed_work() calls from the error handler Date: Mon, 26 May 2014 15:25:36 +0000 Message-ID: <1401117935.3303.3.camel@dabdike> References: <538359DB.9080601@acm.org> <53835A52.9010306@acm.org> <53835C55.6070400@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from mx2.parallels.com ([199.115.105.18]:43828 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752927AbaEZPZm convert rfc822-to-8bit (ORCPT ); Mon, 26 May 2014 11:25:42 -0400 In-Reply-To: <53835C55.6070400@redhat.com> Content-Language: en-US Content-ID: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "pbonzini@redhat.com" Cc: "linux-scsi@vger.kernel.org" , "bvanassche@acm.org" , "hch@infradead.org" , "hare@suse.de" , "axboe@kernel.dk" , "jdl1291@gmail.com" On Mon, 2014-05-26 at 17:23 +0200, Paolo Bonzini wrote: > Il 26/05/2014 17:14, Bart Van Assche ha scritto: > > scsi_put_command() is either invoked before a command is queued or > > after a command has completed. scsi_cmnd.abort_work is scheduled > > after a command has timed out and before it is finished. The block > > layer guarantees that either the softirq_done_fn() or the > > rq_timed_out_fn() function is invoked but not both. This means that > > scsi_put_command() is never invoked while abort_work is scheduled. > > Hence remove the cancel_delayed_work() call from scsi_put_command(). > > > > Similarly, scsi_abort_command() is only invoked from the SCSI > > timeout handler. If scsi_abort_command() is invoked for a SCSI > > command with the SCSI_EH_ABORT_SCHEDULED flag set this means that > > scmd_eh_abort_handler() has already invoked scsi_queue_insert() and > > hence that scsi_cmnd.abort_work is no longer pending. Hence also > > remove the cancel_delayed_work() call from scsi_abort_command(). > > > > Signed-off-by: Bart Van Assche > > Cc: Hannes Reinecke > > Cc: Paolo Bonzini > > Cc: Christoph Hellwig > > Cc: Jens Axboe > > Cc: Joe Lawrence > > --- > > drivers/scsi/scsi.c | 2 +- > > drivers/scsi/scsi_error.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > > index 88d46fe..c972eab 100644 > > --- a/drivers/scsi/scsi.c > > +++ b/drivers/scsi/scsi.c > > @@ -334,7 +334,7 @@ void scsi_put_command(struct scsi_cmnd *cmd) > > list_del_init(&cmd->list); > > spin_unlock_irqrestore(&cmd->device->list_lock, flags); > > > > - cancel_delayed_work(&cmd->abort_work); > > + WARN_ON_ONCE(delayed_work_pending(&cmd->abort_work)); > > > > __scsi_put_command(cmd->device->host, cmd); > > } > > diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c > > index f17aa7a..5232583 100644 > > --- a/drivers/scsi/scsi_error.c > > +++ b/drivers/scsi/scsi_error.c > > @@ -193,7 +193,7 @@ scsi_abort_command(struct scsi_cmnd *scmd) > > SCSI_LOG_ERROR_RECOVERY(3, > > scmd_printk(KERN_INFO, scmd, > > "scmd %p previous abort failed\n", scmd)); > > - cancel_delayed_work(&scmd->abort_work); > > + WARN_ON_ONCE(delayed_work_pending(&scmd->abort_work)); > > return FAILED; > > } > > > > > > I still prefer a BUG_ON in scsi_put_command, but anyway: series Me too, since this is supposed to be an impossible condition that would induce corruption in the cmd free lists and hence make the system unusable. James