[PATCH 5.4 051/123] net: phy: avoid clearing PHY interrupts twice in irq handler

From: Greg Kroah-Hartman
Date: Tue Mar 17 2020 - 07:03:15 EST


From: Heiner Kallweit <hkallweit1@xxxxxxxxx>

[ 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@xxxxxxxx>
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -761,7 +761,8 @@ 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
@@ -524,6 +524,7 @@ 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);