Commit 6b67d2cf authored by Johan Hovold's avatar Johan Hovold Committed by Jeff Johnson
Browse files

wifi: ath12k: fix ring-buffer corruption 

Users of the Lenovo ThinkPad X13s have reported that Wi-Fi sometimes
breaks and the log fills up with errors like:

    ath11k_pci 0006:01:00.0: HTC Rx: insufficient length, got 1484, expected 1492
    ath11k_pci 0006:01:00.0: HTC Rx: insufficient length, got 1460, expected 1484

which based on a quick look at the ath11k driver seemed to indicate some
kind of ring-buffer corruption.

Miaoqing Pan tracked it down to the host seeing the updated destination
ring head pointer before the updated descriptor, and the error handling
for that in turn leaves the ring buffer in an inconsistent state.

While this has not yet been observed with ath12k, the ring-buffer
implementation is very similar to the ath11k one and it suffers from the
same bugs.

Add the missing memory barrier to make sure that the descriptor is read
after the head pointer to address the root cause of the corruption while
fixing up the error handling in case there are ever any (ordering) bugs
on the device side.

Note that the READ_ONCE() are only needed to avoid compiler mischief in
case the ring-buffer helpers are ever inlined.

Tested-on: WCN7850 hw2.0 WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d8899132 ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Cc: stable@vger.kernel.org	# 6.3
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218623
Link: https://lore.kernel.org/20250310010217.3845141-3-quic_miaoqing@quicinc.com


Cc: Miaoqing Pan <quic_miaoqing@quicinc.com>
Signed-off-by: default avatarJohan Hovold <johan+linaro@kernel.org>
Reviewed-by: default avatarMiaoqing Pan <quic_miaoqing@quicinc.com>
Link: https://patch.msgid.link/20250321095219.19369-1-johan+linaro@kernel.org


Signed-off-by: default avatarJeff Johnson <jeff.johnson@oss.qualcomm.com>
parent 89142d34

drivers/net/wireless/ath/ath12k/ce.c

+5 −6
Original line number Diff line number Diff line
@@ -433,11 +433,10 @@ static int ath12k_ce_completed_recv_next(struct ath12k_ce_pipe *pipe, 
		goto err;

	}



	/* Make sure descriptor is read after the head pointer. */

	dma_rmb();



	*nbytes = ath12k_hal_ce_dst_status_get_length(desc);

	if (*nbytes == 0) {

		ret = -EIO;

		goto err;

	}



	*skb = pipe->dest_ring->skb[sw_index];

	pipe->dest_ring->skb[sw_index] = NULL;
@@ -470,8 +469,8 @@ static void ath12k_ce_recv_process_cb(struct ath12k_ce_pipe *pipe) 
		dma_unmap_single(ab->dev, ATH12K_SKB_RXCB(skb)->paddr,

				 max_nbytes, DMA_FROM_DEVICE);



		if (unlikely(max_nbytes < nbytes)) {

			ath12k_warn(ab, "rxed more than expected (nbytes %d, max %d)",

		if (unlikely(max_nbytes < nbytes || nbytes == 0)) {

			ath12k_warn(ab, "unexpected rx length (nbytes %d, max %d)",

				    nbytes, max_nbytes);

			dev_kfree_skb_any(skb);

			continue;

drivers/net/wireless/ath/ath12k/hal.c

+2 −2
Original line number Diff line number Diff line
@@ -1950,7 +1950,7 @@ u32 ath12k_hal_ce_dst_status_get_length(struct hal_ce_srng_dst_status_desc *desc 
{

	u32 len;



	len = le32_get_bits(desc->flags, HAL_CE_DST_STATUS_DESC_FLAGS_LEN);

	len = le32_get_bits(READ_ONCE(desc->flags), HAL_CE_DST_STATUS_DESC_FLAGS_LEN);

	desc->flags &= ~cpu_to_le32(HAL_CE_DST_STATUS_DESC_FLAGS_LEN);



	return len;
@@ -2149,7 +2149,7 @@ void ath12k_hal_srng_access_begin(struct ath12k_base *ab, struct hal_srng *srng) 
		srng->u.src_ring.cached_tp =

			*(volatile u32 *)srng->u.src_ring.tp_addr;

	else

		srng->u.dst_ring.cached_hp = *srng->u.dst_ring.hp_addr;

		srng->u.dst_ring.cached_hp = READ_ONCE(*srng->u.dst_ring.hp_addr);

}



/* Update cached ring head/tail pointers to HW. ath12k_hal_srng_access_begin()