From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [PATCH] uas: replace WARN_ON_ONCE() with assert_spin_locked(). Date: Mon, 11 Aug 2014 20:55:07 +0200 Message-ID: <53E9118B.3020309@redhat.com> References: <1407743966-25325-1-git-send-email-sanjeev_sharma@mentor.com> <20140811181905.GA25727@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43750 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752314AbaHKSzT (ORCPT ); Mon, 11 Aug 2014 14:55:19 -0400 In-Reply-To: <20140811181905.GA25727@roeck-us.net> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Guenter Roeck , Sanjeev Sharma Cc: gregkh@linuxfoundation.org, kraxel@redhat.com, mdharm-usb@one-eyed-alien.net, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Hi, On 08/11/2014 08:19 PM, Guenter Roeck wrote: > On Mon, Aug 11, 2014 at 01:29:26PM +0530, Sanjeev Sharma wrote: >> spin_is_locked() always return false in uniprocessor configuration and therefore it >> would be advise to repalce with assert_spin_locked(). >> >> Signed-off-by: Sanjeev Sharma >> --- >> drivers/usb/storage/uas.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c >> index 3f42785..8e5877d 100644 >> --- a/drivers/usb/storage/uas.c >> +++ b/drivers/usb/storage/uas.c >> @@ -154,7 +154,7 @@ static void uas_mark_cmd_dead(struct uas_dev_info *devinfo, >> struct scsi_cmnd *cmnd = container_of(scp, struct scsi_cmnd, SCp); >> >> uas_log_cmd_state(cmnd, caller); >> - WARN_ON_ONCE(!spin_is_locked(&devinfo->lock)); >> + assert_spin_locked(&devinfo->lock); > > Seems to me that replacing WARN_ON_ONCE (which may be annoying but only > creates a traceback, and only once) with assert_spin_locked (which > crashes the kernel) is a bit drastic. I can see your point, but so far these paranoia checks have never triggered, and having them trigger _always_ one some uni-processor (which is the reason for this patch) to me seems the worse problem of the 2. Ideally we would have a warn_spin_not_locked or such ... Regards, Hans