wifi: ath12k: fix source ring-buffer corruption

commit e834da4cbd6fe1d24f89368bf0c80adcad212726 upstream.

Add the missing memory barrier to make sure that LMAC source ring
descriptors are written before updating the head pointer to avoid
passing stale data to the firmware on weakly ordered architectures like
aarch64.

Note that non-LMAC rings use MMIO write accessors which have the
required write memory barrier.

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/20250617084402.14475-4-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/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
index 18231343474c55bc26d18feafdb65a50ab2e28fc..a88a9eddd52e05dfd04f8275582cca15db88ed64 100644 (file)
--- a/drivers/net/wireless/ath/ath12k/hal.c
+++ b/drivers/net/wireless/ath/ath12k/hal.c
@@ -2142,7 +2142,11 @@ void ath12k_hal_srng_access_end(struct ath12k_base *ab, struct hal_srng *srng)
                if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
                        srng->u.src_ring.last_tp =
                                *(volatile u32 *)srng->u.src_ring.tp_addr;
-                       *srng->u.src_ring.hp_addr = srng->u.src_ring.hp;
+                       /* Make sure descriptor is written before updating the
+                        * head pointer.
+                        */
+                       dma_wmb();
+                       WRITE_ONCE(*srng->u.src_ring.hp_addr, srng->u.src_ring.hp);
                } else {
                        srng->u.dst_ring.last_hp = *srng->u.dst_ring.hp_addr;
                        *srng->u.dst_ring.tp_addr = srng->u.dst_ring.tp;
@@ -2151,6 +2155,10 @@ void ath12k_hal_srng_access_end(struct ath12k_base *ab, struct hal_srng *srng)
                if (srng->ring_dir == HAL_SRNG_DIR_SRC) {
                        srng->u.src_ring.last_tp =
                                *(volatile u32 *)srng->u.src_ring.tp_addr;
+                       /* Assume implementation use an MMIO write accessor
+                        * which has the required wmb() so that the descriptor
+                        * is written before the updating the head pointer.
+                        */
                        ath12k_hif_write32(ab,
                                           (unsigned long)srng->u.src_ring.hp_addr -
                                           (unsigned long)ab->mem,