[PATCH 1/3] wifi: ath11k: fix dest ring-buffer corruption

[Johan Hovold <johan+linaro@xxxxxxxxxx>]

Add the missing memory barriers to make sure that destination ring
descriptors are read after the head pointers to avoid using stale data
on weakly ordered architectures like aarch64.

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@xxxxxxxxxxxxxxx	# 5.6
Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
---
 drivers/net/wireless/ath/ath11k/dp_rx.c | 19 +++++++++++++++++++
 drivers/net/wireless/ath/ath11k/dp_tx.c |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index ea2959305dec..dfe2d889c20f 100644
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -3851,6 +3851,9 @@ int ath11k_dp_process_rx_err(struct ath11k_base *ab, struct napi_struct *napi,
 
 	ath11k_hal_srng_access_begin(ab, srng);
 
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while (budget &&
 	       (desc = ath11k_hal_srng_dst_get_next_entry(ab, srng))) {
 		struct hal_reo_dest_ring *reo_desc = (struct hal_reo_dest_ring *)desc;
@@ -4154,6 +4157,9 @@ int ath11k_dp_rx_process_wbm_err(struct ath11k_base *ab,
 
 	ath11k_hal_srng_access_begin(ab, srng);
 
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while (budget) {
 		rx_desc = ath11k_hal_srng_dst_get_next_entry(ab, srng);
 		if (!rx_desc)
@@ -4280,6 +4286,9 @@ int ath11k_dp_process_rxdma_err(struct ath11k_base *ab, int mac_id, int budget)
 
 	ath11k_hal_srng_access_begin(ab, srng);
 
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while (quota-- &&
 	       (desc = ath11k_hal_srng_dst_get_next_entry(ab, srng))) {
 		ath11k_hal_rx_reo_ent_paddr_get(ab, desc, &paddr, &desc_bank);
@@ -4353,6 +4362,9 @@ void ath11k_dp_process_reo_status(struct ath11k_base *ab)
 
 	ath11k_hal_srng_access_begin(ab, srng);
 
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while ((reo_desc = ath11k_hal_srng_dst_get_next_entry(ab, srng))) {
 		tag = FIELD_GET(HAL_SRNG_TLV_HDR_TAG, *reo_desc);
 
@@ -5168,6 +5180,9 @@ static void ath11k_dp_rx_mon_dest_process(struct ath11k *ar, int mac_id,
 	rx_bufs_used = 0;
 	rx_mon_stats = &pmon->rx_mon_stats;
 
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while ((ring_entry = ath11k_hal_srng_dst_peek(ar->ab, mon_dst_srng))) {
 		struct sk_buff *head_msdu, *tail_msdu;
 
@@ -5630,6 +5645,10 @@ static int ath11k_dp_full_mon_process_rx(struct ath11k_base *ab, int mac_id,
 	spin_lock_bh(&mon_dst_srng->lock);
 
 	ath11k_hal_srng_access_begin(ar->ab, mon_dst_srng);
+
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while ((ring_entry = ath11k_hal_srng_dst_peek(ar->ab, mon_dst_srng))) {
 		head_msdu = NULL;
 		tail_msdu = NULL;
diff --git a/drivers/net/wireless/ath/ath11k/dp_tx.c b/drivers/net/wireless/ath/ath11k/dp_tx.c
index 8522c67baabf..549d17d90503 100644
--- a/drivers/net/wireless/ath/ath11k/dp_tx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_tx.c
@@ -700,6 +700,9 @@ void ath11k_dp_tx_completion_handler(struct ath11k_base *ab, int ring_id)
 
 	ath11k_hal_srng_access_begin(ab, status_ring);
 
+	/* Make sure descriptor is read after the head pointer. */
+	dma_rmb();
+
 	while ((ATH11K_TX_COMPL_NEXT(tx_ring->tx_status_head) !=
 		tx_ring->tx_status_tail) &&
 	       (desc = ath11k_hal_srng_dst_get_next_entry(ab, status_ring))) {
-- 
2.49.0