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Protect the event->class lookup database using an rwlock instead of a

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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.
This commit is contained in:
Robert Watson 2008-10-30 17:47:57 +00:00
parent d6f57961a8
commit c211285f25
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=184482
1 changed files with 15 additions and 8 deletions
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23
sys/security/audit/audit_bsm_klib.c
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@ -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, au_class_t class)
*/
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, au_class_t class)
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);