From 1f7f504dcd9d1262437bdcf4fa071e41dec1af03 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Tue, 24 Sep 2019 18:45:38 +0000
Subject: [PATCH] can: rx-offload: can_rx_offload_irq_offload_fifo(): continue on error
Git-commit: 1f7f504dcd9d1262437bdcf4fa071e41dec1af03
Patch-mainline: v5.4-rc7
References: bsc#1051510

In case of a resource shortage, i.e. the rx_offload queue will overflow
or a skb fails to be allocated (due to OOM),
can_rx_offload_offload_one() will call mailbox_read() to discard the
mailbox and return an ERR_PTR.

If the hardware FIFO is empty can_rx_offload_offload_one() will return
NULL.

In case a CAN frame was read from the hardware,
can_rx_offload_offload_one() returns the skb containing it.

Without this patch can_rx_offload_irq_offload_fifo() bails out if no skb
returned, regardless of the reason.

Similar to can_rx_offload_irq_offload_timestamp() in case of a resource
shortage the whole FIFO should be discarded, to avoid an IRQ storm and
give the system some time to recover. However if the FIFO is empty the
loop can be left.

With this patch the loop is left in case of empty FIFO, but not on
errors.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/can/rx-offload.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/rx-offload.c b/drivers/net/can/rx-offload.c
index 2ea8676579a9..84cae167e42f 100644
--- a/drivers/net/can/rx-offload.c
+++ b/drivers/net/can/rx-offload.c
@@ -248,7 +248,9 @@ int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
 
 	while (1) {
 		skb = can_rx_offload_offload_one(offload, 0);
-		if (IS_ERR_OR_NULL(skb))
+		if (IS_ERR(skb))
+			continue;
+		if (!skb)
 			break;
 
 		skb_queue_tail(&offload->skb_queue, skb);
-- 
2.16.4