Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755467AbbGCQC7 (ORCPT ); Fri, 3 Jul 2015 12:02:59 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:58230 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755705AbbGCQCx (ORCPT ); Fri, 3 Jul 2015 12:02:53 -0400 Date: Fri, 3 Jul 2015 09:02:51 -0700 From: Christoph Hellwig To: Calvin Owens Cc: Nagalakshmi Nandigama , Praveen Krishnamoorthy , Sreekanth Reddy , Abhijit Mahajan , MPT-FusionLinux.pdl@avagotech.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 6/6] Fix unsafe fw_event_list usage Message-ID: <20150703160251.GB11815@infradead.org> References: <1431661322-3097935-1-git-send-email-calvinowens@fb.com> <1433821856-2815280-1-git-send-email-calvinowens@fb.com> <1433821856-2815280-7-git-send-email-calvinowens@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433821856-2815280-7-git-send-email-calvinowens@fb.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1520 Lines: 39 On Mon, Jun 08, 2015 at 08:50:56PM -0700, Calvin Owens wrote: > Since the fw_event deletes itself from the list, cleanup_queue() can > walk onto garbage pointers or walk off into freed memory. > > This refactors the code in _scsih_fw_event_cleanup_queue() to not > iterate over the fw_event_list without a lock. I think this really should be folded into the previous one, with the fixes in this one the other refcounting change don't make a whole lot sense. > +static struct fw_event_work *dequeue_next_fw_event(struct MPT2SAS_ADAPTER *ioc) > +{ > + unsigned long flags; > + struct fw_event_work *fw_event = NULL; > + > + spin_lock_irqsave(&ioc->fw_event_lock, flags); > + if (!list_empty(&ioc->fw_event_list)) { > + fw_event = list_first_entry(&ioc->fw_event_list, > + struct fw_event_work, list); > + list_del_init(&fw_event->list); > + fw_event_work_get(fw_event); > + } > + spin_unlock_irqrestore(&ioc->fw_event_lock, flags); > + > + return fw_event; Shouldn't we have a reference for each item on the list that gets transfer to whomever removes it from the list? Additionally _firmware_event_work should call dequeue_next_fw_event first in the function so that item is off the list before we process it, and can then just drop the reference once it's done. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/