linux-kernel - [PATCH net-next v2 2/4] net: dql: Separate queue function responsibilities

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Date: Mon,  8 Apr 2024 10:25:54 -0700
From: Breno Leitao <leitao@...ian.org>
To: kuba@...nel.org,
	davem@...emloft.net,
	pabeni@...hat.com,
	edumazet@...gle.com
Cc: linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: [PATCH net-next v2 2/4] net: dql: Separate queue function responsibilities

The dql_queued() function currently handles both queuing object counts
and populating bitmaps for reporting stalls.

This commit splits the bitmap population into a separate function,
allowing for conditional invocation in scenarios where the feature is
disabled.

This refactor maintains functionality while improving code
organization.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 include/linux/dynamic_queue_limits.h | 44 ++++++++++++++++------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/include/linux/dynamic_queue_limits.h b/include/linux/dynamic_queue_limits.h
index ff9c65841ae8..9980df0b7247 100644
--- a/include/linux/dynamic_queue_limits.h
+++ b/include/linux/dynamic_queue_limits.h
@@ -83,28 +83,11 @@ struct dql {
 #define DQL_MAX_OBJECT (UINT_MAX / 16)
 #define DQL_MAX_LIMIT ((UINT_MAX / 2) - DQL_MAX_OBJECT)
 
-/*
- * Record number of objects queued. Assumes that caller has already checked
- * availability in the queue with dql_avail.
- */
-static inline void dql_queued(struct dql *dql, unsigned int count)
+/* Populate the bitmap to be processed later in dql_check_stall() */
+static inline void dql_queue_stall(struct dql *dql)
 {
 	unsigned long map, now, now_hi, i;
 
-	if (WARN_ON_ONCE(count > DQL_MAX_OBJECT))
-		return;
-
-	dql->last_obj_cnt = count;
-
-	/* We want to force a write first, so that cpu do not attempt
-	 * to get cache line containing last_obj_cnt, num_queued, adj_limit
-	 * in Shared state, but directly does a Request For Ownership
-	 * It is only a hint, we use barrier() only.
-	 */
-	barrier();
-
-	dql->num_queued += count;
-
 	now = jiffies;
 	now_hi = now / BITS_PER_LONG;
 
@@ -134,6 +117,29 @@ static inline void dql_queued(struct dql *dql, unsigned int count)
 		WRITE_ONCE(DQL_HIST_ENT(dql, now_hi), map | BIT_MASK(now));
 }
 
+/*
+ * Record number of objects queued. Assumes that caller has already checked
+ * availability in the queue with dql_avail.
+ */
+static inline void dql_queued(struct dql *dql, unsigned int count)
+{
+	if (WARN_ON_ONCE(count > DQL_MAX_OBJECT))
+		return;
+
+	dql->last_obj_cnt = count;
+
+	/* We want to force a write first, so that cpu do not attempt
+	 * to get cache line containing last_obj_cnt, num_queued, adj_limit
+	 * in Shared state, but directly does a Request For Ownership
+	 * It is only a hint, we use barrier() only.
+	 */
+	barrier();
+
+	dql->num_queued += count;
+
+	dql_queue_stall(dql);
+}
+
 /* Returns how many objects can be queued, < 0 indicates over limit. */
 static inline int dql_avail(const struct dql *dql)
 {
-- 
2.43.0