6.6-stable review patch. If anyone has any objections, please let me know.
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From: Johan Hovold johan+linaro@kernel.org
commit 6b67d2cf14ea997061f61e9c8afd4e1c0f22acb9 upstream.
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: d889913205cf ("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: Johan Hovold johan+linaro@kernel.org Reviewed-by: Miaoqing Pan quic_miaoqing@quicinc.com Link: https://patch.msgid.link/20250321095219.19369-1-johan+linaro@kernel.org Signed-off-by: Jeff Johnson jeff.johnson@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/wireless/ath/ath12k/ce.c | 11 +++++------ drivers/net/wireless/ath/ath12k/hal.c | 4 ++-- 2 files changed, 7 insertions(+), 8 deletions(-)
--- a/drivers/net/wireless/ath/ath12k/ce.c +++ b/drivers/net/wireless/ath/ath12k/ce.c @@ -343,11 +343,10 @@ static int ath12k_ce_completed_recv_next 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; @@ -380,8 +379,8 @@ static void ath12k_ce_recv_process_cb(st 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; --- a/drivers/net/wireless/ath/ath12k/hal.c +++ b/drivers/net/wireless/ath/ath12k/hal.c @@ -1565,7 +1565,7 @@ u32 ath12k_hal_ce_dst_status_get_length( { 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; @@ -1734,7 +1734,7 @@ void ath12k_hal_srng_access_begin(struct 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()