[PATCH 1/2] wifi: ath11k: fix RCU stall while reaping monitor destination ring

[Kang Yang]

From: P Praneesh <quic_ppranees at quicinc.com>

While processing the monitor destination ring, MSDUs are reaped from the
link descriptor based on the corresponding buf_id.

However, sometimes the driver cannot obtain a valid buffer corresponding
to the buf_id received from the hardware. This causes an infinite loop
in the  the link descriptor based on the corresponding buf_id. However,
sometimes the driver cannot obtain a valid buffer corresponding to the
buf_id received from the hardware. This causes an infinite loop in the
destination processing, resulting in a kernel crash.

kernel log:
ath11k_pci 0000:58:00.0: data msdu_pop: invalid buf_id 309
ath11k_pci 0000:58:00.0: data dp_rx_monitor_link_desc_return failed
ath11k_pci 0000:58:00.0: data msdu_pop: invalid buf_id 309
ath11k_pci 0000:58:00.0: data dp_rx_monitor_link_desc_return failed
……

Fix this by skipping the problematic buf_id and reaping the next entry,
replacing the break with the next MSDU processing.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1
Signed-off-by: P Praneesh <quic_ppranees at quicinc.com>
Signed-off-by: Kang Yang <quic_kangyang at quicinc.com>
---
 drivers/net/wireless/ath/ath11k/dp_rx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index c087d8a0f5b2..072963d3396c 100644
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -4781,7 +4781,7 @@ ath11k_dp_rx_mon_mpdu_pop(struct ath11k *ar, int mac_id,
 			if (!msdu) {
 				ath11k_dbg(ar->ab, ATH11K_DBG_DATA,
 					   "msdu_pop: invalid buf_id %d\n", buf_id);
-				break;
+				goto next_msdu;
 			}
 			rxcb = ATH11K_SKB_RXCB(msdu);
 			if (!rxcb->unmapped) {
@@ -5405,7 +5405,7 @@ ath11k_dp_rx_full_mon_mpdu_pop(struct ath11k *ar,
 					   "full mon msdu_pop: invalid buf_id %d\n",
 					    buf_id);
 				spin_unlock_bh(&rx_ring->idr_lock);
-				break;
+				goto next_msdu;
 			}
 			idr_remove(&rx_ring->bufs_idr, buf_id);
 			spin_unlock_bh(&rx_ring->idr_lock);
-- 
2.34.1