If mcu_skb_prepare_msg is not implemented, incrementing skb refcount does not
work for mcu message retry. In some cases (e.g. on SDIO), shared skbs can trigger
a BUG_ON, crashing the system.
Fix this by only incrementing refcount if retry is actually supported.
Fixes: 3688c18b65ae ("wifi: mt76: mt7915: retry mcu messages")
Reported-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx> #KernelCI
Tested-by: Alper Nebi Yasak <alpernebiyasak@xxxxxxxxx>
Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
---
drivers/net/wireless/mediatek/mt76/mcu.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mcu.c b/drivers/net/wireless/mediatek/mt76/mcu.c
index 98da82b74094..3353012e8542 100644
--- a/drivers/net/wireless/mediatek/mt76/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mcu.c
@@ -84,13 +84,16 @@ int mt76_mcu_skb_send_and_get_msg(struct mt76_dev *dev, struct sk_buff *skb,
mutex_lock(&dev->mcu.mutex);
if (dev->mcu_ops->mcu_skb_prepare_msg) {
+ orig_skb = skb;
ret = dev->mcu_ops->mcu_skb_prepare_msg(dev, skb, cmd, &seq);
if (ret < 0)
goto out;
}
retry:
- orig_skb = skb_get(skb);
+ /* orig skb might be needed for retry, mcu_skb_send_msg consumes it */
+ if (orig_skb)
+ skb_get(orig_skb);
ret = dev->mcu_ops->mcu_skb_send_msg(dev, skb, cmd, &seq);
if (ret < 0)
goto out;
@@ -105,7 +108,7 @@ int mt76_mcu_skb_send_and_get_msg(struct mt76_dev *dev, struct sk_buff *skb,
do {
skb = mt76_mcu_get_response(dev, expires);
if (!skb && !test_bit(MT76_MCU_RESET, &dev->phy.state) &&
- retry++ < dev->mcu_ops->max_retry) {
+ orig_skb && retry++ < dev->mcu_ops->max_retry) {
dev_err(dev->dev, "Retry message %08x (seq %d)\n",
cmd, seq);
skb = orig_skb;
--
2.46.0
