From a2a9d9826277c9d76f5c19fd98a27c6145fa6fbd Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Tue, 17 Sep 2024 12:58:18 +0200 Subject: [PATCH] wifi: mt76: do not increase mcu skb refcount if retry is not supported MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 #KernelCI Tested-by: Alper Nebi Yasak Signed-off-by: Felix Fietkau --- mcu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mcu.c b/mcu.c index 98da82b7..3353012e 100644 --- a/mcu.c +++ b/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 @@ retry: 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;