Module Name: src
Committed By: thorpej
Date: Thu Sep 1 02:35:06 UTC 2022
Modified Files:
src/sys/net: pktqueue.c
Log Message:
pktq_dequeue(): Prevent packets from getting stuck beind barrier markers.
pktq_barrier() ensures that all packets enqueued before the barrier have
been dequeued before the barrier returns. However, previously, pktq_dequeue()
would return NULL when a barrier marker was encountered. If there were
packets queued up behind the marker and no additional softint were scheduled
for the pktqueue, those packets would end up stranded. pktq_dequeue() now
continues to the next slot after the marker, ensuring that processing can
continue after the barrier has been signaled.
To generate a diff of this commit:
cvs rdiff -u -r1.16 -r1.17 src/sys/net/pktqueue.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/net/pktqueue.c
diff -u src/sys/net/pktqueue.c:1.16 src/sys/net/pktqueue.c:1.17
--- src/sys/net/pktqueue.c:1.16 Tue Dec 21 04:09:32 2021
+++ src/sys/net/pktqueue.c Thu Sep 1 02:35:06 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: pktqueue.c,v 1.16 2021/12/21 04:09:32 knakahara Exp $ */
+/* $NetBSD: pktqueue.c,v 1.17 2022/09/01 02:35:06 thorpej Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -36,7 +36,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pktqueue.c,v 1.16 2021/12/21 04:09:32 knakahara Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pktqueue.c,v 1.17 2022/09/01 02:35:06 thorpej Exp $");
#ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h"
@@ -410,7 +410,16 @@ pktq_dequeue(pktqueue_t *pq)
if (__predict_false(m == PKTQ_MARKER)) {
/* Note the marker entry. */
atomic_inc_uint(&pq->pq_barrier);
- return NULL;
+
+ /* Get the next queue entry. */
+ m = pcq_get(pktq_pcq(pq, ci));
+
+ /*
+ * There can only be one barrier operation pending
+ * on a pktqueue at any given time, so we can assert
+ * that the next item is not a marker.
+ */
+ KASSERT(m != PKTQ_MARKER);
}
if (__predict_true(m != NULL)) {
pktq_inc_count(pq, PQCNT_DEQUEUE);
