From 6b67d2cf14ea997061f61e9c8afd4e1c0f22acb9 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Fri, 21 Mar 2025 10:52:19 +0100 Subject: [PATCH] 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: 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 Signed-off-by: Johan Hovold Reviewed-by: Miaoqing Pan Link: https://patch.msgid.link/20250321095219.19369-1-johan+linaro@kernel.org Signed-off-by: Jeff Johnson --- drivers/net/wireless/ath/ath12k/ce.c | 11 +++++------ drivers/net/wireless/ath/ath12k/hal.c | 4 ++-- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/ath/ath12k/ce.c b/drivers/net/wireless/ath/ath12k/ce.c index 7a5656aceebe..47821a3b060b 100644 --- a/drivers/net/wireless/ath/ath12k/ce.c +++ b/drivers/net/wireless/ath/ath12k/ce.c @@ -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; diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c index 276121ca31d1..a301898e5849 100644 --- a/drivers/net/wireless/ath/ath12k/hal.c +++ b/drivers/net/wireless/ath/ath12k/hal.c @@ -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() -- 2.50.1