linux-kernel - [PATCH 5.5 062/151] net: phy: avoid clearing PHY interrupts twice in irq handler

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Date:   Tue, 17 Mar 2020 11:54:32 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Michael Walle <michael@...le.cc>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.5 062/151] net: phy: avoid clearing PHY interrupts twice in irq handler

From: Heiner Kallweit <hkallweit1@...il.com>

[ Upstream commit 249bc9744e165abe74ae326f43e9d70bad54c3b7 ]

On all PHY drivers that implement did_interrupt() reading the interrupt
status bits clears them. This means we may loose an interrupt that
is triggered between calling did_interrupt() and phy_clear_interrupt().
As part of the fix make it a requirement that did_interrupt() clears
the interrupt.

The Fixes tag refers to the first commit where the patch applies
cleanly.

Fixes: 49644e68f472 ("net: phy: add callback for custom interrupt handler to struct phy_driver")
Reported-by: Michael Walle <michael@...le.cc>
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/phy/phy.c |    3 ++-
 include/linux/phy.h   |    1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -702,7 +702,8 @@ static irqreturn_t phy_interrupt(int irq
 		phy_trigger_machine(phydev);
 	}
 
-	if (phy_clear_interrupt(phydev))
+	/* did_interrupt() may have cleared the interrupt already */
+	if (!phydev->drv->did_interrupt && phy_clear_interrupt(phydev))
 		goto phy_err;
 	return IRQ_HANDLED;
 
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -531,6 +531,7 @@ struct phy_driver {
 	/*
 	 * Checks if the PHY generated an interrupt.
 	 * For multi-PHY devices with shared PHY interrupt pin
+	 * Set interrupt bits have to be cleared.
 	 */
 	int (*did_interrupt)(struct phy_device *phydev);