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 8157ce533a60521f21d466eb4de45d9735b19484 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 ath12k_hal_srng_access_begin() helper for symmetry with follow-on fixes for source ring buffer corruption which will add barriers to ath12k_hal_srng_access_end().
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 Signed-off-by: Johan Hovold johan+linaro@kernel.org Reviewed-by: Baochen Qiang quic_bqiang@quicinc.com Link: https://patch.msgid.link/20250617084402.14475-2-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/ath12k/ce.c | 3 --- drivers/net/wireless/ath/ath12k/hal.c | 17 ++++++++++++++--- 2 files changed, 14 insertions(+), 6 deletions(-)
--- a/drivers/net/wireless/ath/ath12k/ce.c +++ b/drivers/net/wireless/ath/ath12k/ce.c @@ -343,9 +343,6 @@ 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);
*skb = pipe->dest_ring->skb[sw_index]; --- a/drivers/net/wireless/ath/ath12k/hal.c +++ b/drivers/net/wireless/ath/ath12k/hal.c @@ -1728,13 +1728,24 @@ void *ath12k_hal_srng_src_get_next_reape
void ath12k_hal_srng_access_begin(struct ath12k_base *ab, struct hal_srng *srng) { + u32 hp; + lockdep_assert_held(&srng->lock);
- if (srng->ring_dir == HAL_SRNG_DIR_SRC) + 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); + } else { + 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(); + } + } }
/* Update cached ring head/tail pointers to HW. ath12k_hal_srng_access_begin()