svn commit: r188227 - in stable/7/sys: . contrib/pf dev/ath/ath_hal dev/cxgb security/audit

[Robert Watson]

Author: rwatson
Date: Fri Feb  6 12:22:00 2009
New Revision: 188227
URL: http://svn.freebsd.org/changeset/base/188227

Log:
  Merge r184489 from head to stable/7:
  
    When we drop an audit record going to and audit pipe because the audit
    pipe has overflowed, drop the newest, rather than oldest, record.  This
    makes overflow drop behavior consistent with memory allocation failure
    leading to drop, avoids touching the consumer end of the queue from a
    producer, and lowers the CPU overhead of dropping a record by dropping
    before memory allocation and copying.
  
    Obtained from:        Apple, Inc.

Modified:
  stable/7/sys/   (props changed)
  stable/7/sys/contrib/pf/   (props changed)
  stable/7/sys/dev/ath/ath_hal/   (props changed)
  stable/7/sys/dev/cxgb/   (props changed)
  stable/7/sys/security/audit/audit_pipe.c

Modified: stable/7/sys/security/audit/audit_pipe.c
==============================================================================
--- stable/7/sys/security/audit/audit_pipe.c	Fri Feb  6 12:20:08 2009	(r188226)
+++ stable/7/sys/security/audit/audit_pipe.c	Fri Feb  6 12:22:00 2009	(r188227)
@@ -396,17 +396,22 @@ audit_pipe_preselect(au_id_t auid, au_ev
 
 /*
  * Append individual record to a queue -- allocate queue-local buffer, and
- * add to the queue.  We try to drop from the head of the queue so that more
- * recent events take precedence over older ones, but if allocation fails we
- * do drop the new event.
+ * add to the queue.  If the queue is full or we can't allocate memory, drop
+ * the newest record.
  */
 static void
 audit_pipe_append(struct audit_pipe *ap, void *record, u_int record_len)
 {
-	struct audit_pipe_entry *ape, *ape_remove;
+	struct audit_pipe_entry *ape;
 
 	mtx_assert(&audit_pipe_mtx, MA_OWNED);
 
+	if (ap->ap_qlen >= ap->ap_qlimit) {
+		ap->ap_drops++;
+		audit_pipe_drops++;
+		return;
+	}
+
 	ape = malloc(sizeof(*ape), M_AUDIT_PIPE_ENTRY, M_NOWAIT | M_ZERO);
 	if (ape == NULL) {
 		ap->ap_drops++;
@@ -425,15 +430,6 @@ audit_pipe_append(struct audit_pipe *ap,
 	bcopy(record, ape->ape_record, record_len);
 	ape->ape_record_len = record_len;
 
-	if (ap->ap_qlen >= ap->ap_qlimit) {
-		ape_remove = TAILQ_FIRST(&ap->ap_queue);
-		TAILQ_REMOVE(&ap->ap_queue, ape_remove, ape_queue);
-		audit_pipe_entry_free(ape_remove);
-		ap->ap_qlen--;
-		ap->ap_drops++;
-		audit_pipe_drops++;
-	}
-
 	TAILQ_INSERT_TAIL(&ap->ap_queue, ape, ape_queue);
 	ap->ap_inserts++;
 	ap->ap_qlen++;