Subject: [PATCH v14 3/8] net: split off _napi_busy_loop()

From: Stefan Roesch <[email-masked]>
Date: Mon, 5 Jun 2023 14:20:04 -0700

This splits off the function _napi_busy_loop from the commonality of
napi_busy_loop() and napi_busy_loop_rcu().

Signed-off-by: Stefan Roesch <[email-masked]>
---
 net/core/dev.c | 66 ++++++++++++++++++++++++--------------------------
 1 file changed, 31 insertions(+), 35 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index fcd4a6a70646..2a2d9bae1eb4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6214,39 +6214,10 @@ static inline void __napi_busy_poll(struct napi_busy_poll_ctx *ctx,
 	local_bh_enable();
 }
 
-/*
- * Warning: can exit without calling need_resched().
- */
-void napi_busy_loop_rcu(unsigned int napi_id,
-		    bool (*loop_end)(void *, unsigned long),
-		    void *loop_end_arg, bool prefer_busy_poll, u16 budget)
-{
-	unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
-	struct napi_busy_poll_ctx ctx = {};
-
-	ctx.napi = napi_by_id(napi_id);
-	if (!ctx.napi)
-		return;
-
-	preempt_disable();
-	for (;;) {
-		__napi_busy_poll(&ctx, prefer_busy_poll, budget);
-
-		if (!loop_end || loop_end(loop_end_arg, start_time))
-			break;
-		if (unlikely(need_resched()))
-			break;
-
-		cpu_relax();
-	}
-	if (ctx.napi_poll)
-		busy_poll_stop(ctx.napi, ctx.have_poll_lock, prefer_busy_poll, budget);
-	preempt_enable();
-}
-
-void napi_busy_loop(unsigned int napi_id,
+static void _napi_busy_loop(unsigned int napi_id,
 		    bool (*loop_end)(void *, unsigned long),
-		    void *loop_end_arg, bool prefer_busy_poll, u16 budget)
+		    void *loop_end_arg, bool prefer_busy_poll, u16 budget,
+		    bool rcu)
 {
 	unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
 	struct napi_busy_poll_ctx ctx = {};
@@ -6254,7 +6225,8 @@ void napi_busy_loop(unsigned int napi_id,
 restart:
 	ctx.napi_poll = NULL;
 
-	rcu_read_lock();
+	if (rcu)
+		rcu_read_lock();
 
 	ctx.napi = napi_by_id(napi_id);
 	if (!ctx.napi)
@@ -6268,8 +6240,12 @@ void napi_busy_loop(unsigned int napi_id,
 			break;
 
 		if (unlikely(need_resched())) {
+			if (rcu)
+				break;
+
 			if (ctx.napi_poll)
-				busy_poll_stop(ctx.napi, ctx.have_poll_lock, prefer_busy_poll, budget);
+				busy_poll_stop(ctx.napi, ctx.have_poll_lock,
+					       prefer_busy_poll, budget);
 			preempt_enable();
 			rcu_read_unlock();
 			cond_resched();
@@ -6283,7 +6259,27 @@ void napi_busy_loop(unsigned int napi_id,
 		busy_poll_stop(ctx.napi, ctx.have_poll_lock, prefer_busy_poll, budget);
 	preempt_enable();
 out:
-	rcu_read_unlock();
+	if (rcu)
+		rcu_read_unlock();
+}
+
+/*
+ * Warning: can exit without calling need_resched().
+ */
+void napi_busy_loop_rcu(unsigned int napi_id,
+		    bool (*loop_end)(void *, unsigned long),
+		    void *loop_end_arg, bool prefer_busy_poll, u16 budget)
+{
+	_napi_busy_loop(napi_id, loop_end, loop_end_arg, prefer_busy_poll,
+			budget, true);
+}
+
+void napi_busy_loop(unsigned int napi_id,
+		    bool (*loop_end)(void *, unsigned long),
+		    void *loop_end_arg, bool prefer_busy_poll, u16 budget)
+{
+	_napi_busy_loop(napi_id, loop_end, loop_end_arg, prefer_busy_poll,
+			budget, false);
 }
 EXPORT_SYMBOL(napi_busy_loop);
 
-- 
2.39.1