Date: Tue, 1 Jul 2014 06:29:15 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r268074 - head/sys/kern Message-ID: <201407010629.s616TFul082441@svn.freebsd.org>
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Author: mjg Date: Tue Jul 1 06:29:15 2014 New Revision: 268074 URL: http://svnweb.freebsd.org/changeset/base/268074 Log: Perform a lockless check in sigacts_shared. It is used only during execve (i.e. singlethreaded), so there is no fear of returning 'not shared' which soon becomes 'shared'. While here reorganize the code a little to avoid proc lock/unlock in shared case. MFC after: 1 week Modified: head/sys/kern/kern_exec.c head/sys/kern/kern_sig.c Modified: head/sys/kern/kern_exec.c ============================================================================== --- head/sys/kern/kern_exec.c Tue Jul 1 06:23:48 2014 (r268073) +++ head/sys/kern/kern_exec.c Tue Jul 1 06:29:15 2014 (r268074) @@ -621,18 +621,17 @@ interpret: * handlers. In execsigs(), the new process will have its signals * reset. */ - PROC_LOCK(p); - oldcred = crcopysafe(p, newcred); if (sigacts_shared(p->p_sigacts)) { oldsigacts = p->p_sigacts; - PROC_UNLOCK(p); newsigacts = sigacts_alloc(); sigacts_copy(newsigacts, oldsigacts); - PROC_LOCK(p); - p->p_sigacts = newsigacts; } else oldsigacts = NULL; + PROC_LOCK(p); + if (oldsigacts) + p->p_sigacts = newsigacts; + oldcred = crcopysafe(p, newcred); /* Stop profiling */ stopprofclock(p); Modified: head/sys/kern/kern_sig.c ============================================================================== --- head/sys/kern/kern_sig.c Tue Jul 1 06:23:48 2014 (r268073) +++ head/sys/kern/kern_sig.c Tue Jul 1 06:29:15 2014 (r268074) @@ -3453,10 +3453,6 @@ sigacts_copy(struct sigacts *dest, struc int sigacts_shared(struct sigacts *ps) { - int shared; - mtx_lock(&ps->ps_mtx); - shared = ps->ps_refcnt > 1; - mtx_unlock(&ps->ps_mtx); - return (shared); + return (ps->ps_refcnt > 1); }
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