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); _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
