netdev - [RFC net-next 2/4] net: stmmac: move to threaded IRQ

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Message-Id: <20211210193556.1349090-3-yannick.vignon@oss.nxp.com>
Date:   Fri, 10 Dec 2021 20:35:54 +0100
From:   Yannick Vignon <yannick.vignon@....nxp.com>
To:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        netdev@...r.kernel.org, Ong Boon Leong <boon.leong.ong@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jose Abreu <joabreu@...opsys.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Wei Wang <weiwan@...gle.com>,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Xiaoliang Yang <xiaoliang.yang_1@....com>, mingkai.hu@....com,
        Joakim Zhang <qiangqing.zhang@....com>,
        sebastien.laveze@....com
Cc:     Yannick Vignon <yannick.vignon@....com>
Subject: [RFC net-next 2/4] net: stmmac: move to threaded IRQ

From: Yannick Vignon <yannick.vignon@....com>

WIP (seems to generate warnings/error on startup)

When an IRQ is forced threaded, execution of the handler remains protected
by local_bh_disable()/local_bh_enable() calls to keep the semantics of the
IRQ context and avoid deadlocks. However, this also creates a contention
point where a higher prio interrupt handler gets blocked by a lower prio
task already holding the lock. Even though priority inheritance kicks in in
such a case, the lower prio task can still execute for an indefinite time.

Move the stmmac interrupts to be explicitely threaded, so that high
priority traffic can be processed without delay even if another piece of
code was already running with BH disabled.

Signed-off-by: Yannick Vignon <yannick.vignon@....com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 28 +++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 748195697e5a..8bf24902be3c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3460,8 +3460,8 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
 	/* For common interrupt */
 	int_name = priv->int_name_mac;
 	sprintf(int_name, "%s:%s", dev->name, "mac");
-	ret = request_irq(dev->irq, stmmac_mac_interrupt,
-			  0, int_name, dev);
+	ret = request_threaded_irq(dev->irq, NULL, stmmac_interrupt,
+			  IRQF_ONESHOT, int_name, dev);
 	if (unlikely(ret < 0)) {
 		netdev_err(priv->dev,
 			   "%s: alloc mac MSI %d (error: %d)\n",
@@ -3476,9 +3476,9 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
 	if (priv->wol_irq > 0 && priv->wol_irq != dev->irq) {
 		int_name = priv->int_name_wol;
 		sprintf(int_name, "%s:%s", dev->name, "wol");
-		ret = request_irq(priv->wol_irq,
-				  stmmac_mac_interrupt,
-				  0, int_name, dev);
+		ret = request_threaded_irq(priv->wol_irq,
+				  NULL, stmmac_mac_interrupt,
+				  IRQF_ONESHOT, int_name, dev);
 		if (unlikely(ret < 0)) {
 			netdev_err(priv->dev,
 				   "%s: alloc wol MSI %d (error: %d)\n",
@@ -3494,9 +3494,9 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
 	if (priv->lpi_irq > 0 && priv->lpi_irq != dev->irq) {
 		int_name = priv->int_name_lpi;
 		sprintf(int_name, "%s:%s", dev->name, "lpi");
-		ret = request_irq(priv->lpi_irq,
-				  stmmac_mac_interrupt,
-				  0, int_name, dev);
+		ret = request_threaded_irq(priv->lpi_irq,
+				  NULL, stmmac_mac_interrupt,
+				  IRQF_ONESHOT, int_name, dev);
 		if (unlikely(ret < 0)) {
 			netdev_err(priv->dev,
 				   "%s: alloc lpi MSI %d (error: %d)\n",
@@ -3605,8 +3605,8 @@ static int stmmac_request_irq_single(struct net_device *dev)
 	enum request_irq_err irq_err;
 	int ret;
 
-	ret = request_irq(dev->irq, stmmac_interrupt,
-			  IRQF_SHARED, dev->name, dev);
+	ret = request_threaded_irq(dev->irq, NULL, stmmac_interrupt,
+			  IRQF_SHARED | IRQF_ONESHOT, dev->name, dev);
 	if (unlikely(ret < 0)) {
 		netdev_err(priv->dev,
 			   "%s: ERROR: allocating the IRQ %d (error: %d)\n",
@@ -3619,8 +3619,8 @@ static int stmmac_request_irq_single(struct net_device *dev)
 	 * is used for WoL
 	 */
 	if (priv->wol_irq > 0 && priv->wol_irq != dev->irq) {
-		ret = request_irq(priv->wol_irq, stmmac_interrupt,
-				  IRQF_SHARED, dev->name, dev);
+		ret = request_threaded_irq(priv->wol_irq, NULL, stmmac_interrupt,
+				  IRQF_SHARED | IRQF_ONESHOT, dev->name, dev);
 		if (unlikely(ret < 0)) {
 			netdev_err(priv->dev,
 				   "%s: ERROR: allocating the WoL IRQ %d (%d)\n",
@@ -3632,8 +3632,8 @@ static int stmmac_request_irq_single(struct net_device *dev)
 
 	/* Request the IRQ lines */
 	if (priv->lpi_irq > 0 && priv->lpi_irq != dev->irq) {
-		ret = request_irq(priv->lpi_irq, stmmac_interrupt,
-				  IRQF_SHARED, dev->name, dev);
+		ret = request_threaded_irq(priv->lpi_irq, NULL, stmmac_interrupt,
+				  IRQF_SHARED | IRQF_ONESHOT, dev->name, dev);
 		if (unlikely(ret < 0)) {
 			netdev_err(priv->dev,
 				   "%s: ERROR: allocating the LPI IRQ %d (%d)\n",
-- 
2.25.1