Date: Tue, 6 Jan 2009 14:15:38 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r186825 - head/sys/security/audit Message-ID: <200901061415.n06EFc91033354@svn.freebsd.org>
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Author: rwatson Date: Tue Jan 6 14:15:38 2009 New Revision: 186825 URL: http://svn.freebsd.org/changeset/base/186825 Log: Do a lockless read of the audit pipe list before grabbing the audit pipe lock in order to avoid the lock acquire hit if the pipe list is very likely empty. Obtained from: TrustedBSD Project MFC after: 3 weeks Sponsored by: Apple, Inc. Modified: head/sys/security/audit/audit_pipe.c Modified: head/sys/security/audit/audit_pipe.c ============================================================================== --- head/sys/security/audit/audit_pipe.c Tue Jan 6 14:10:30 2009 (r186824) +++ head/sys/security/audit/audit_pipe.c Tue Jan 6 14:15:38 2009 (r186825) @@ -436,6 +436,10 @@ audit_pipe_preselect(au_id_t auid, au_ev { struct audit_pipe *ap; + /* Lockless read to avoid acquiring the global lock if not needed. */ + if (TAILQ_EMPTY(&audit_pipe_list)) + return (0); + AUDIT_PIPE_LIST_RLOCK(); TAILQ_FOREACH(ap, &audit_pipe_list, ap_list) { AUDIT_PIPE_LOCK(ap);
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