From: Deren Wu <[email protected]>
mt7921s driver may receive frames with fragment buffers. If there is a
CTS packet received in monitor mode, the payload is 10 bytes only and
need 6 bytes header padding after RXD buffer. However, only RXD in the
first linear buffer, if we pull buffer size RXD-size+6 bytes with
skb_pull(), that would trigger "BUG_ON(skb->len < skb->data_len)" in
__skb_pull().
To avoid the nonlinear buffer issue, enlarge the RXD size from 128 to
136 to make sure all MCU operation in linear buffer.
136 = 128 + 8
128 : RXD size
8 : max header padding length
[ 52.007562] kernel BUG at include/linux/skbuff.h:2313!
[ 52.007578] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[ 52.007987] pc : skb_pull+0x48/0x4c
[ 52.008015] lr : mt7921_queue_rx_skb+0x494/0x890 [mt7921_common]
[ 52.008361] Call trace:
[ 52.008377] skb_pull+0x48/0x4c
[ 52.008400] mt76s_net_worker+0x134/0x1b0 [mt76_sdio 35339a92c6eb7d4bbcc806a1d22f56365565135c]
[ 52.008431] __mt76_worker_fn+0xe8/0x170 [mt76 ef716597d11a77150bc07e3fdd68eeb0f9b56917]
[ 52.008449] kthread+0x148/0x3ac
[ 52.008466] ret_from_fork+0x10/0x30
Co-developed-by: Sean Wang <[email protected]>
Signed-off-by: Sean Wang <[email protected]>
Signed-off-by: Deren Wu <[email protected]>
---
drivers/net/wireless/mediatek/mt76/mt76.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 5e10fe156926..4f4ce3b3df54 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -19,7 +19,8 @@
#define MT_MCU_RING_SIZE 32
#define MT_RX_BUF_SIZE 2048
-#define MT_SKB_HEAD_LEN 128
+/* 136 = 128+8. 128: RXD, 8:max header padding*/
+#define MT_SKB_HEAD_LEN 136
#define MT_MAX_NON_AQL_PKT 16
#define MT_TXQ_FREE_THR 32
--
2.18.0
Hi Felix,
I need to submit v2 patch. Please drop this one.
Thanks,
Deren
On Thu, 2022-03-03 at 11:28 +0800, Deren Wu wrote:
> From: Deren Wu <[email protected]>
>
> mt7921s driver may receive frames with fragment buffers. If there is
> a
> CTS packet received in monitor mode, the payload is 10 bytes only and
> need 6 bytes header padding after RXD buffer. However, only RXD in
> the
> first linear buffer, if we pull buffer size RXD-size+6 bytes with
> skb_pull(), that would trigger "BUG_ON(skb->len < skb->data_len)" in
> __skb_pull().
>
> To avoid the nonlinear buffer issue, enlarge the RXD size from 128 to
> 136 to make sure all MCU operation in linear buffer.
>
> 136 = 128 + 8
> 128 : RXD size
> 8 : max header padding length
>
> [ 52.007562] kernel BUG at include/linux/skbuff.h:2313!
> [ 52.007578] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
> [ 52.007987] pc : skb_pull+0x48/0x4c
> [ 52.008015] lr : mt7921_queue_rx_skb+0x494/0x890 [mt7921_common]
> [ 52.008361] Call trace:
> [ 52.008377] skb_pull+0x48/0x4c
> [ 52.008400] mt76s_net_worker+0x134/0x1b0 [mt76_sdio
> 35339a92c6eb7d4bbcc806a1d22f56365565135c]
> [ 52.008431] __mt76_worker_fn+0xe8/0x170 [mt76
> ef716597d11a77150bc07e3fdd68eeb0f9b56917]
> [ 52.008449] kthread+0x148/0x3ac
> [ 52.008466] ret_from_fork+0x10/0x30
>
> Co-developed-by: Sean Wang <[email protected]>
> Signed-off-by: Sean Wang <[email protected]>
> Signed-off-by: Deren Wu <[email protected]>
> ---
> drivers/net/wireless/mediatek/mt76/mt76.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h
> b/drivers/net/wireless/mediatek/mt76/mt76.h
> index 5e10fe156926..4f4ce3b3df54 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76.h
> +++ b/drivers/net/wireless/mediatek/mt76/mt76.h
> @@ -19,7 +19,8 @@
>
> #define MT_MCU_RING_SIZE 32
> #define MT_RX_BUF_SIZE 2048
> -#define MT_SKB_HEAD_LEN 128
> +/* 136 = 128+8. 128: RXD, 8:max header padding*/
> +#define MT_SKB_HEAD_LEN 136
>
> #define MT_MAX_NON_AQL_PKT 16
> #define MT_TXQ_FREE_THR 32