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 051bf0d73084fddd88340a427b79af751a2a9917..c4437889f1593371710f450973d269aef68221f0 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 626d7f4186700553499a45499b3dcd35987bd4f1..be00ea6fbf8b6a442119c7227111ae357f2c06aa 100644 (file)
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -2661,9 +2661,6 @@ 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 ec64fbf9aa82697bbc157a2a991a8474aaace6a0..39d1333a0f5e3a9a8e5f91259a9311c9d77c7b3e 100644 (file)
--- 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 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)