From owner-svn-src-head@freebsd.org Sat Apr 21 17:05:01 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 03FF6FB3571; Sat, 21 Apr 2018 17:05:00 +0000 (UTC) (envelope-from jtl@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 9EB877DA2E; Sat, 21 Apr 2018 17:05:00 +0000 (UTC) (envelope-from jtl@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 mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 954841B3B; Sat, 21 Apr 2018 17:05:00 +0000 (UTC) (envelope-from jtl@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w3LH50lT056340; Sat, 21 Apr 2018 17:05:00 GMT (envelope-from jtl@FreeBSD.org) Received: (from jtl@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w3LH50Dk056339; Sat, 21 Apr 2018 17:05:00 GMT (envelope-from jtl@FreeBSD.org) Message-Id: <201804211705.w3LH50Dk056339@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: jtl set sender to jtl@FreeBSD.org using -f From: "Jonathan T. Looney" Date: Sat, 21 Apr 2018 17:05:00 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r332860 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: jtl X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 332860 X-SVN-Commit-Repository: base 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: 2.1.25 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: Sat, 21 Apr 2018 17:05:01 -0000 Author: jtl Date: Sat Apr 21 17:05:00 2018 New Revision: 332860 URL: https://svnweb.freebsd.org/changeset/base/332860 Log: When running with INVARIANTS, the kernel contains extra checks. However, these assumptions may not hold true once we've panic'd. Therefore, the checks hold less value after a panic. Additionally, if one of the checks fails while we are already panic'd, this creates a double-panic which can interfere with debugging the original panic. Therefore, this commit allows an administrator to suppress a response to KASSERT checks after a panic by setting a tunable/sysctl. The tunable/sysctl (debug.kassert.suppress_in_panic) defaults to being enabled. Reviewed by: kib Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D12920 Modified: head/sys/kern/kern_shutdown.c Modified: head/sys/kern/kern_shutdown.c ============================================================================== --- head/sys/kern/kern_shutdown.c Sat Apr 21 15:15:47 2018 (r332859) +++ head/sys/kern/kern_shutdown.c Sat Apr 21 17:05:00 2018 (r332860) @@ -642,6 +642,7 @@ static int kassert_do_log = 1; static int kassert_log_pps_limit = 4; static int kassert_log_mute_at = 0; static int kassert_log_panic_at = 0; +static int kassert_suppress_in_panic = 1; static int kassert_warnings = 0; SYSCTL_NODE(_debug, OID_AUTO, kassert, CTLFLAG_RW, NULL, "kassert options"); @@ -676,6 +677,10 @@ SYSCTL_INT(_debug_kassert, OID_AUTO, log_pps_limit, CT SYSCTL_INT(_debug_kassert, OID_AUTO, log_mute_at, CTLFLAG_RWTUN, &kassert_log_mute_at, 0, "max number of KASSERTS to log"); +SYSCTL_INT(_debug_kassert, OID_AUTO, suppress_in_panic, CTLFLAG_RWTUN, + &kassert_suppress_in_panic, 0, + "KASSERTs will be suppressed while handling a panic"); + static int kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS); SYSCTL_PROC(_debug_kassert, OID_AUTO, kassert, @@ -707,6 +712,10 @@ kassert_panic(const char *fmt, ...) { static char buf[256]; va_list ap; + + /* If we already panic'd, don't create a double-fault. */ + if (panicstr != NULL && kassert_suppress_in_panic) + return; va_start(ap, fmt); (void)vsnprintf(buf, sizeof(buf), fmt, ap);