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 9d8efec46508a1bda1c4345fe352517fa287586a..39d9aad33bc690d7d4514dbe366422e7851d7bae 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 007d869590423501237f4c0e1bdd4431df8272d0..66a00f330734d12d6995c3d12539b383c4f10cac 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 f38decae77a93515c8362d4cb274ea55d32e4bd8..41aca752ff6681cbbab1094200521725bc56236b 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)