svn commit: r184482 - head/sys/security/audit

[Robert Watson]

Author: rwatson
Date: Thu Oct 30 17:47:57 2008
New Revision: 184482
URL: http://svn.freebsd.org/changeset/base/184482

Log:
  Protect the event->class lookup database using an rwlock instead of a
  mutex, as it's rarely changed but frequently accessed read-only from
  multiple threads, so a potentially significant source of contention.
  
  MFC after:    1 month
  Sponsored by: Apple, Inc.

Modified:
  head/sys/security/audit/audit_bsm_klib.c

Modified: head/sys/security/audit/audit_bsm_klib.c
==============================================================================
--- head/sys/security/audit/audit_bsm_klib.c    Thu Oct 30 16:29:04 2008        
(r184481)
+++ head/sys/security/audit/audit_bsm_klib.c    Thu Oct 30 17:47:57 2008        
(r184482)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999-2005 Apple Inc.
+ * Copyright (c) 1999-2008 Apple Inc.
  * Copyright (c) 2005 Robert N. M. Watson
  * All rights reserved.
  *
@@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/malloc.h>
 #include <sys/mount.h>
 #include <sys/proc.h>
+#include <sys/rwlock.h>
 #include <sys/sem.h>
 #include <sys/sbuf.h>
 #include <sys/syscall.h>
@@ -65,9 +66,15 @@ struct evclass_list {
 };
 
 static MALLOC_DEFINE(M_AUDITEVCLASS, "audit_evclass", "Audit event class");
-static struct mtx              evclass_mtx;
+static struct rwlock           evclass_lock;
 static struct evclass_list     evclass_hash[EVCLASSMAP_HASH_TABLE_SIZE];
 
+#define        EVCLASS_LOCK_INIT()     rw_init(&evclass_lock, "evclass_lock")
+#define        EVCLASS_RLOCK()         rw_rlock(&evclass_lock)
+#define        EVCLASS_RUNLOCK()       rw_runlock(&evclass_lock)
+#define        EVCLASS_WLOCK()         rw_wlock(&evclass_lock)
+#define        EVCLASS_WUNLOCK()       rw_wunlock(&evclass_lock)
+
 /*
  * Look up the class for an audit event in the class mapping table.
  */
@@ -78,7 +85,7 @@ au_event_class(au_event_t event)
        struct evclass_elem *evc;
        au_class_t class;
 
-       mtx_lock(&evclass_mtx);
+       EVCLASS_RLOCK();
        evcl = &evclass_hash[event % EVCLASSMAP_HASH_TABLE_SIZE];
        class = 0;
        LIST_FOREACH(evc, &evcl->head, entry) {
@@ -88,7 +95,7 @@ au_event_class(au_event_t event)
                }
        }
 out:
-       mtx_unlock(&evclass_mtx);
+       EVCLASS_RUNLOCK();
        return (class);
 }
 
@@ -111,12 +118,12 @@ au_evclassmap_insert(au_event_t event, a
         */
        evc_new = malloc(sizeof(*evc), M_AUDITEVCLASS, M_WAITOK);
 
-       mtx_lock(&evclass_mtx);
+       EVCLASS_WLOCK();
        evcl = &evclass_hash[event % EVCLASSMAP_HASH_TABLE_SIZE];
        LIST_FOREACH(evc, &evcl->head, entry) {
                if (evc->event == event) {
                        evc->class = class;
-                       mtx_unlock(&evclass_mtx);
+                       EVCLASS_WUNLOCK();
                        free(evc_new, M_AUDITEVCLASS);
                        return;
                }
@@ -125,7 +132,7 @@ au_evclassmap_insert(au_event_t event, a
        evc->event = event;
        evc->class = class;
        LIST_INSERT_HEAD(&evcl->head, evc, entry);
-       mtx_unlock(&evclass_mtx);
+       EVCLASS_WUNLOCK();
 }
 
 void
@@ -133,7 +140,7 @@ au_evclassmap_init(void)
 {
        int i;
 
-       mtx_init(&evclass_mtx, "evclass_mtx", NULL, MTX_DEF);
+       EVCLASS_LOCK_INIT();
        for (i = 0; i < EVCLASSMAP_HASH_TABLE_SIZE; i++)
                LIST_INIT(&evclass_hash[i].head);
 
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