6.16-stable review patch. If anyone has any objections, please let me know.
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From: Johan Hovold johan+linaro@kernel.org
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 --- drivers/net/wireless/ath/ath12k/hal.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/drivers/net/wireless/ath/ath12k/hal.c +++ b/drivers/net/wireless/ath/ath12k/hal.c @@ -2178,7 +2178,11 @@ void ath12k_hal_srng_access_end(struct a 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; @@ -2187,6 +2191,10 @@ void ath12k_hal_srng_access_end(struct a 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,