Date: Sun, 11 Jan 2015 12:17:27 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r276969 - stable/10/sys/kern Message-ID: <201501111217.t0BCHRqn086751@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: hselasky Date: Sun Jan 11 12:17:27 2015 New Revision: 276969 URL: https://svnweb.freebsd.org/changeset/base/276969 Log: MFC r276532 and r276626: The "cnputs_mtx" mutex must be allowed to recurse. Debug prints and/or witness printouts in the console driver clients can cause this mutex to recurse by calls to "printf()" from witness for example. In particular this can happen if "debug.witness.skipspin=0" is set in the boot environment. Modified: stable/10/sys/kern/kern_cons.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/kern/kern_cons.c ============================================================================== --- stable/10/sys/kern/kern_cons.c Sun Jan 11 12:08:17 2015 (r276968) +++ stable/10/sys/kern/kern_cons.c Sun Jan 11 12:17:27 2015 (r276969) @@ -505,6 +505,13 @@ cnputs(char *p) int unlock_reqd = 0; if (use_cnputs_mtx) { + /* + * NOTE: Debug prints and/or witness printouts in + * console driver clients can cause the "cnputs_mtx" + * mutex to recurse. Simply return if that happens. + */ + if (mtx_owned(&cnputs_mtx)) + return; mtx_lock_spin(&cnputs_mtx); unlock_reqd = 1; }
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201501111217.t0BCHRqn086751>