netdev - [PATCH wpan-next 08/11] net: mac802154: Add a warning in the hot path

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Message-Id: <20220427164659.106447-9-miquel.raynal@bootlin.com>
Date:   Wed, 27 Apr 2022 18:46:56 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@...enfreihafen.org>,
        linux-wpan@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        David Girault <david.girault@...vo.com>,
        Romuald Despres <romuald.despres@...vo.com>,
        Frederic Blain <frederic.blain@...vo.com>,
        Nicolas Schodet <nico@...fr.eu.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: [PATCH wpan-next 08/11] net: mac802154: Add a warning in the hot path

We should never start a transmission after the queue has been stopped.

But because it might work we don't kill the function here but rather
warn loudly the user that something is wrong.

Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
---
 net/mac802154/ieee802154_i.h |  8 ++++++++
 net/mac802154/tx.c           |  2 ++
 net/mac802154/util.c         | 18 ++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index b55fdefb0b34..cb61a4abaf37 100644
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -178,6 +178,14 @@ bool ieee802154_queue_is_held(struct ieee802154_local *local);
  */
 void ieee802154_stop_queue(struct ieee802154_local *local);
 
+/**
+ * ieee802154_queue_is_stopped - check whether ieee802154 queue was stopped
+ * @local: main mac object
+ *
+ * Goes through all the interfaces and indicates if they are all stopped or not.
+ */
+bool ieee802154_queue_is_stopped(struct ieee802154_local *local);
+
 /* MIB callbacks */
 void mac802154_dev_set_page_channel(struct net_device *dev, u8 page, u8 chan);
 
diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c
index a8a83f0167bf..021dddfea542 100644
--- a/net/mac802154/tx.c
+++ b/net/mac802154/tx.c
@@ -124,6 +124,8 @@ bool ieee802154_queue_is_held(struct ieee802154_local *local)
 static netdev_tx_t
 ieee802154_hot_tx(struct ieee802154_local *local, struct sk_buff *skb)
 {
+	WARN_ON_ONCE(ieee802154_queue_is_stopped(local));
+
 	return ieee802154_tx(local, skb);
 }
 
diff --git a/net/mac802154/util.c b/net/mac802154/util.c
index 847e0864b575..cfd17a7db532 100644
--- a/net/mac802154/util.c
+++ b/net/mac802154/util.c
@@ -44,6 +44,24 @@ void ieee802154_stop_queue(struct ieee802154_local *local)
 	rcu_read_unlock();
 }
 
+bool ieee802154_queue_is_stopped(struct ieee802154_local *local)
+{
+	struct ieee802154_sub_if_data *sdata;
+	bool stopped = true;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+		if (!sdata->dev)
+			continue;
+
+		if (!netif_queue_stopped(sdata->dev))
+			stopped = false;
+	}
+	rcu_read_unlock();
+
+	return stopped;
+}
+
 enum hrtimer_restart ieee802154_xmit_ifs_timer(struct hrtimer *timer)
 {
 	struct ieee802154_local *local =
-- 
2.27.0