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can: sja1000: fix max irq loop handling

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commit 30db4451c7 upstream.

Reading the interrupt register `SJA1000_IR` causes all of its bits to be
reset. If we ever reach the condition of handling more than
`SJA1000_MAX_IRQ` IRQs, we will have read the register and reset all its
bits but without actually handling the interrupt inside of the loop
body.

This may, among other issues, cause us to never `netif_wake_queue()`
again after a transmission interrupt.

Fixes: 429da1cc84 ("can: Driver for the SJA1000 CAN controller")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Mühlbacher <tmuehlbacher@posteo.net>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20251115153437.11419-1-tmuehlbacher@posteo.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Mühlbacher
2025-11-15 15:34:56 +00:00
committed by Greg Kroah-Hartman
parent bd1415efba
commit e36369dfa2
1 changed files with 2 additions and 2 deletions
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drivers/net/can/sja1000/sja1000.c
+2 -2
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@@ -508,8 +508,8 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
if (priv->read_reg(priv, SJA1000_IER) == IRQ_OFF)
goto out;
while ((isrc = priv->read_reg(priv, SJA1000_IR)) &&
(n < SJA1000_MAX_IRQ)) {
while ((n < SJA1000_MAX_IRQ) &&
(isrc = priv->read_reg(priv, SJA1000_IR))) {
status = priv->read_reg(priv, SJA1000_SR);
/* check for absent controller due to hw unplug */