From owner-svn-src-head@freebsd.org Fri Nov 11 20:09:56 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0EFD8C3CA6E; Fri, 11 Nov 2016 20:09:56 +0000 (UTC) (envelope-from cem@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id D1C8E1287; Fri, 11 Nov 2016 20:09:55 +0000 (UTC) (envelope-from cem@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id uABK9t5Q014439; Fri, 11 Nov 2016 20:09:55 GMT (envelope-from cem@FreeBSD.org) Received: (from cem@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id uABK9t0i014438; Fri, 11 Nov 2016 20:09:55 GMT (envelope-from cem@FreeBSD.org) Message-Id: <201611112009.uABK9t0i014438@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: cem set sender to cem@FreeBSD.org using -f From: "Conrad E. Meyer" Date: Fri, 11 Nov 2016 20:09:54 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r308553 - head/sys/dev/ioat X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Nov 2016 20:09:56 -0000 Author: cem Date: Fri Nov 11 20:09:54 2016 New Revision: 308553 URL: https://svnweb.freebsd.org/changeset/base/308553 Log: ioat(4): Fix race between process_events and reset_hw In the case where a hardware error is detected during ioat_process_events, hardware may advance (by one descriptor, probably) and a subsequent ioat_process_events may race the intended ioat_reset_hw followup. In that case, the second process_events would observe a completion update that does not match the software "last_seen" status, and attempt to successfully complete already-failed descriptors. Guard against this race with the resetting_cleanup flag. Reviewed by: bdrewery, markj Sponsored by: Dell EMC Isilon Modified: head/sys/dev/ioat/ioat.c Modified: head/sys/dev/ioat/ioat.c ============================================================================== --- head/sys/dev/ioat/ioat.c Fri Nov 11 20:08:45 2016 (r308552) +++ head/sys/dev/ioat/ioat.c Fri Nov 11 20:09:54 2016 (r308553) @@ -765,6 +765,15 @@ out: mtx_lock(&ioat->submit_lock); mtx_lock(&ioat->cleanup_lock); ioat->quiescing = TRUE; + /* + * This is safe to do here because we have both locks and the submit + * queue is quiesced. We know that we will drain all outstanding + * events, so ioat_reset_hw can't deadlock. It is necessary to + * protect other ioat_process_event threads from racing ioat_reset_hw, + * reading an indeterminate hw state, and attempting to continue + * issuing completions. + */ + ioat->resetting_cleanup = TRUE; chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET); if (1 <= g_ioat_debug_level)