Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755248AbcDFNVn (ORCPT ); Wed, 6 Apr 2016 09:21:43 -0400 Received: from mail-qg0-f67.google.com ([209.85.192.67]:36589 "EHLO mail-qg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754338AbcDFNVl (ORCPT ); Wed, 6 Apr 2016 09:21:41 -0400 Subject: Re: [PATCH] csiostor: Fix backwards locking in the function __csio_unreg_rnode To: Julian Calaby References: <1459891143-20451-1-git-send-email-bastienphilbert@gmail.com> Cc: jejb@linux.vnet.ibm.com, "Martin K. Petersen" , linux-scsi , "linux-kernel@vger.kernel.org" From: Bastien Philbert Message-ID: <57050D62.3090802@gmail.com> Date: Wed, 6 Apr 2016 09:21:38 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1664 Lines: 43 On 2016-04-06 03:48 AM, Julian Calaby wrote: > Hi Bastien, > > On Wed, Apr 6, 2016 at 7:19 AM, Bastien Philbert > wrote: >> This fixes backwards locking in the function __csio_unreg_rnode to >> properly lock before the call to the function csio_unreg_rnode and >> not unlock with spin_unlock_irq as this would not allow the proper >> protection for concurrent access on the shared csio_hw structure >> pointer hw. In addition switch the locking after the critical region >> function call to properly unlock instead with spin_unlock_irq on >> >> Signed-off-by: Bastien Philbert >> --- >> drivers/scsi/csiostor/csio_rnode.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/scsi/csiostor/csio_rnode.c b/drivers/scsi/csiostor/csio_rnode.c >> index e9c3b04..029a09e 100644 >> --- a/drivers/scsi/csiostor/csio_rnode.c >> +++ b/drivers/scsi/csiostor/csio_rnode.c >> @@ -580,9 +580,9 @@ __csio_unreg_rnode(struct csio_rnode *rn) >> ln->last_scan_ntgts--; >> } >> >> - spin_unlock_irq(&hw->lock); >> - csio_unreg_rnode(rn); >> spin_lock_irq(&hw->lock); >> + csio_unreg_rnode(rn); >> + spin_unlock_irq(&hw->lock); > > Are you _certain_ this is correct? This construct usually appears when > a function has a particular lock held, then needs to unlock it to call > some other function. Are you _certain_ that this isn't the case? > > Thanks, > Yes I am pretty certain this is correct. I checked the paths that called this function and it was weired that none of them gradded the spinlock before hand. Cheers, Bastien