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 8c1ba5091fa9a2d1478da63173b16a701bdf86bb upstream.
Add the missing memory barrier to make sure that destination ring descriptors are read after the head pointers to avoid using stale data on weakly ordered architectures like aarch64.
The barrier is added to the ath11k_hal_srng_access_begin() helper for symmetry with follow-on fixes for source ring buffer corruption which will add barriers to ath11k_hal_srng_access_end().
Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices") Cc: stable@vger.kernel.org # 5.6 Signed-off-by: Johan Hovold johan+linaro@kernel.org Reviewed-by: Baochen Qiang quic_bqiang@quicinc.com Link: https://patch.msgid.link/20250604143457.26032-2-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/ath11k/ce.c | 3 --- drivers/net/wireless/ath/ath11k/dp_rx.c | 3 --- drivers/net/wireless/ath/ath11k/hal.c | 12 +++++++++++- 3 files changed, 11 insertions(+), 7 deletions(-)
--- a/drivers/net/wireless/ath/ath11k/ce.c +++ b/drivers/net/wireless/ath/ath11k/ce.c @@ -393,9 +393,6 @@ static int ath11k_ce_completed_recv_next goto err; }
- /* Make sure descriptor is read after the head pointer. */ - dma_rmb(); - *nbytes = ath11k_hal_ce_dst_status_get_length(desc);
*skb = pipe->dest_ring->skb[sw_index]; --- a/drivers/net/wireless/ath/ath11k/dp_rx.c +++ b/drivers/net/wireless/ath/ath11k/dp_rx.c @@ -2662,9 +2662,6 @@ int ath11k_dp_process_rx(struct ath11k_b try_again: ath11k_hal_srng_access_begin(ab, srng);
- /* Make sure descriptor is read after the head pointer. */ - dma_rmb(); - while (likely(desc = (struct hal_reo_dest_ring *)ath11k_hal_srng_dst_get_next_entry(ab, srng))) { --- a/drivers/net/wireless/ath/ath11k/hal.c +++ b/drivers/net/wireless/ath/ath11k/hal.c @@ -796,13 +796,23 @@ u32 *ath11k_hal_srng_src_peek(struct ath
void ath11k_hal_srng_access_begin(struct ath11k_base *ab, struct hal_srng *srng) { + u32 hp; + lockdep_assert_held(&srng->lock);
if (srng->ring_dir == HAL_SRNG_DIR_SRC) { srng->u.src_ring.cached_tp = *(volatile u32 *)srng->u.src_ring.tp_addr; } else { - srng->u.dst_ring.cached_hp = READ_ONCE(*srng->u.dst_ring.hp_addr); + hp = READ_ONCE(*srng->u.dst_ring.hp_addr); + + if (hp != srng->u.dst_ring.cached_hp) { + srng->u.dst_ring.cached_hp = hp; + /* Make sure descriptor is read after the head + * pointer. + */ + dma_rmb(); + }
/* Try to prefetch the next descriptor in the ring */ if (srng->flags & HAL_SRNG_FLAGS_CACHED)