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 2b7bee6664728619dda1c1e6981088a59c6ca19f..33b9764eaa91671ae2031efece969250b83ff746 100644 (file)
--- 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_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 df493d1760623e2ead00c19f0caf3844dcfeab7c..f93f4889e049b4dd02b5e98628e035871eb5c243 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)