wifi: ath11k: fix dest ring-buffer corruption

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>

diff --git a/drivers/net/wireless/ath/ath11k/ce.c b/drivers/net/wireless/ath/ath11k/ce.c
index 746038006eb46586c0e47fdeb89faf1ccc4f0c28..6a4895310159dd8bd7a5d386c0bd1f9fcbfa2d6d 100644 (file)
--- 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(struct ath11k_ce_pipe *pipe,
                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];

diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index 9230a965f6f0eb99fa147d90e28679838209efef..065fc40e254166b54a7b93cdfa8d0dc652d1392e 100644 (file)
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -2650,9 +2650,6 @@ int ath11k_dp_process_rx(struct ath11k_base *ab, int ring_id,
 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))) {

diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c
index cab11a35f9115d35bb2ad7198735cf5f7344358d..30c41b6188ab0d719ab46b1d04207bd6e259b94a 100644 (file)
--- a/drivers/net/wireless/ath/ath11k/hal.c
+++ b/drivers/net/wireless/ath/ath11k/hal.c
@@ -823,13 +823,23 @@ u32 *ath11k_hal_srng_src_peek(struct ath11k_base *ab, struct hal_srng *srng)
 
 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)