linux-kernel - [PATCH net-next v3 4/8] net: ethernet: fs_enet: only protect the .restart() call in .adjust

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Message-ID: <20240904171822.64652-5-maxime.chevallier@bootlin.com>
Date: Wed,  4 Sep 2024 19:18:17 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: davem@...emloft.net,
	Pantelis Antoniou <pantelis.antoniou@...il.com>,
	Andrew Lunn <andrew@...n.ch>,
	Jakub Kicinski <kuba@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Russell King <linux@...linux.org.uk>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Florian Fainelli <f.fainelli@...il.com>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: Maxime Chevallier <maxime.chevallier@...tlin.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	thomas.petazzoni@...tlin.com,
	Herve Codina <herve.codina@...tlin.com>,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH net-next v3 4/8] net: ethernet: fs_enet: only protect the .restart() call in .adjust_link

When .adjust_link() gets called, it runs in thread context, with the
phydev->lock held. We only need to protect the fep->fecp/fccp/sccp
register that are accessed within the .restart() function from
concurrent access from the interrupts.

These registers are being protected by the fep->lock spinlock, so we can
move the spinlock protection around the .restart() call instead of the
entire adjust_link() call. By doing so, we can simplify further the
.adjust_link() callback and avoid the intermediate helper.

Suggested-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
---
 .../ethernet/freescale/fs_enet/fs_enet-main.c  | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c b/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
index caca81b3ccb6..b320e55dcb81 100644
--- a/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
+++ b/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
@@ -607,10 +607,11 @@ static void fs_timeout(struct net_device *dev, unsigned int txqueue)
 }
 
 /* generic link-change handler - should be sufficient for most cases */
-static void generic_adjust_link(struct  net_device *dev)
+static void fs_adjust_link(struct  net_device *dev)
 {
 	struct fs_enet_private *fep = netdev_priv(dev);
 	struct phy_device *phydev = dev->phydev;
+	unsigned long flags;
 	int new_state = 0;
 
 	if (phydev->link) {
@@ -630,8 +631,11 @@ static void generic_adjust_link(struct  net_device *dev)
 			fep->oldlink = 1;
 		}
 
-		if (new_state)
+		if (new_state) {
+			spin_lock_irqsave(&fep->lock, flags);
 			fep->ops->restart(dev);
+			spin_unlock_irqrestore(&fep->lock, flags);
+		}
 	} else if (fep->oldlink) {
 		new_state = 1;
 		fep->oldlink = 0;
@@ -643,16 +647,6 @@ static void generic_adjust_link(struct  net_device *dev)
 		phy_print_status(phydev);
 }
 
-static void fs_adjust_link(struct net_device *dev)
-{
-	struct fs_enet_private *fep = netdev_priv(dev);
-	unsigned long flags;
-
-	spin_lock_irqsave(&fep->lock, flags);
-	generic_adjust_link(dev);
-	spin_unlock_irqrestore(&fep->lock, flags);
-}
-
 static int fs_init_phy(struct net_device *dev)
 {
 	struct fs_enet_private *fep = netdev_priv(dev);
-- 
2.46.0