From: Ondřej Surý <ondrej@isc.org>
Date: Wed, 3 Jul 2024 09:51:09 +0000 (+0200)
Subject: Clarify that cds_wfcq_dequeue_blocking() doesn't block if empty
X-Git-Tag: alessio/regression/026024a6ae~5^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=912eaf6cb9f153cc8551e1ad0d8aa7b7a725fc84;p=thirdparty%2Fbind9.git

Clarify that cds_wfcq_dequeue_blocking() doesn't block if empty
---

diff --git a/lib/isc/quota.c b/lib/isc/quota.c
index ad58f338106..a4ddebc6125 100644
--- a/lib/isc/quota.c
+++ b/lib/isc/quota.c
@@ -70,6 +70,10 @@ isc_quota_release(isc_quota_t *quota) {
 	 * We are using the cds_wfcq_dequeue_blocking() variant here that
 	 * has an internal mutex because we need synchronization on
 	 * multiple dequeues running from different threads.
+	 *
+	 * NOTE: cds_wfcq_dequeue_blocking() checks whether the queue is free
+	 * with cds_wfcq_empty() before acquiring the internal lock, so if
+	 * there's nothing queued, the call should be very lightweight.
 	 */
 	struct cds_wfcq_node *node =
 		cds_wfcq_dequeue_blocking(&quota->jobs.head, &quota->jobs.tail);