Date: Fri, 2 Jan 2015 13:10:34 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r276532 - head/sys/kern Message-ID: <201501021310.t02DAYhn001838@svn.freebsd.org>
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Author: hselasky Date: Fri Jan 2 13:10:33 2015 New Revision: 276532 URL: https://svnweb.freebsd.org/changeset/base/276532 Log: 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. MFC after: 1 week Modified: head/sys/kern/kern_cons.c Modified: head/sys/kern/kern_cons.c ============================================================================== --- head/sys/kern/kern_cons.c Fri Jan 2 08:57:36 2015 (r276531) +++ head/sys/kern/kern_cons.c Fri Jan 2 13:10:33 2015 (r276532) @@ -601,7 +601,13 @@ static void cn_drvinit(void *unused) { - mtx_init(&cnputs_mtx, "cnputs_mtx", NULL, MTX_SPIN | MTX_NOWITNESS); + /* + * NOTE: Debug prints and/or witness printouts in console + * driver clients can cause the "cnputs_mtx" mutex to + * recurse. Make sure the "MTX_RECURSE" flags is set! + */ + mtx_init(&cnputs_mtx, "cnputs_mtx", NULL, MTX_SPIN | + MTX_NOWITNESS | MTX_RECURSE); use_cnputs_mtx = 1; }
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