openwrt/target/linux/generic/backport-6.6/770-net-introduce-napi_is_scheduled-helper.patch

From 7f3eb2174512fe6c9c0f062e96eccb0d3cc6d5cd Mon Sep 17 00:00:00 2001
From: Christian Marangi <ansuelsmth@gmail.com>
Date: Wed, 18 Oct 2023 14:35:47 +0200
Subject: [PATCH] net: introduce napi_is_scheduled helper

We currently have napi_if_scheduled_mark_missed that can be used to
check if napi is scheduled but that does more thing than simply checking
it and return a bool. Some driver already implement custom function to
check if napi is scheduled.

Drop these custom function and introduce napi_is_scheduled that simply
check if napi is scheduled atomically.

Update any driver and code that implement a similar check and instead
use this new helper.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 drivers/net/ethernet/chelsio/cxgb3/sge.c  |  8 --------
 drivers/net/wireless/realtek/rtw89/core.c |  2 +-
 include/linux/netdevice.h                 | 23 +++++++++++++++++++++++
 net/core/dev.c                            |  2 +-
 4 files changed, 25 insertions(+), 10 deletions(-)

--- a/drivers/net/ethernet/chelsio/cxgb3/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/sge.c
@@ -2501,14 +2501,6 @@ static int napi_rx_handler(struct napi_s
 	return work_done;
 }
 
-/*
- * Returns true if the device is already scheduled for polling.
- */
-static inline int napi_is_scheduled(struct napi_struct *napi)
-{
-	return test_bit(NAPI_STATE_SCHED, &napi->state);
-}
-
 /**
  *	process_pure_responses - process pure responses from a response queue
  *	@adap: the adapter
--- a/drivers/net/wireless/realtek/rtw89/core.c
+++ b/drivers/net/wireless/realtek/rtw89/core.c
@@ -1744,7 +1744,7 @@ static void rtw89_core_rx_to_mac80211(st
 	struct napi_struct *napi = &rtwdev->napi;
 
 	/* In low power mode, napi isn't scheduled. Receive it to netif. */
-	if (unlikely(!test_bit(NAPI_STATE_SCHED, &napi->state)))
+	if (unlikely(!napi_is_scheduled(napi)))
 		napi = NULL;
 
 	rtw89_core_hw_to_sband_rate(rx_status);
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -480,6 +480,29 @@ static inline bool napi_prefer_busy_poll
 	return test_bit(NAPI_STATE_PREFER_BUSY_POLL, &n->state);
 }
 
+/**
+ * napi_is_scheduled - test if NAPI is scheduled
+ * @n: NAPI context
+ *
+ * This check is "best-effort". With no locking implemented,
+ * a NAPI can be scheduled or terminate right after this check
+ * and produce not precise results.
+ *
+ * NAPI_STATE_SCHED is an internal state, napi_is_scheduled
+ * should not be used normally and napi_schedule should be
+ * used instead.
+ *
+ * Use only if the driver really needs to check if a NAPI
+ * is scheduled for example in the context of delayed timer
+ * that can be skipped if a NAPI is already scheduled.
+ *
+ * Return True if NAPI is scheduled, False otherwise.
+ */
+static inline bool napi_is_scheduled(struct napi_struct *n)
+{
+	return test_bit(NAPI_STATE_SCHED, &n->state);
+}
+
 bool napi_schedule_prep(struct napi_struct *n);
 
 /**
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6602,7 +6602,7 @@ static int __napi_poll(struct napi_struc
 	 * accidentally calling ->poll() when NAPI is not scheduled.
 	 */
 	work = 0;
-	if (test_bit(NAPI_STATE_SCHED, &n->state)) {
+	if (napi_is_scheduled(n)) {
 		work = n->poll(n, weight);
 		trace_napi_poll(n, work, weight);
 	}