wifi: ath11k: fix ring-buffer corruption

Users of the Lenovo ThinkPad X13s have reported that Wi-Fi sometimes
breaks and the log fills up with errors like:

    ath11k_pci 0006:01:00.0: HTC Rx: insufficient length, got 1484, expected 1492
    ath11k_pci 0006:01:00.0: HTC Rx: insufficient length, got 1460, expected 1484

which based on a quick look at the driver seemed to indicate some kind
of ring-buffer corruption.

Miaoqing Pan tracked it down to the host seeing the updated destination
ring head pointer before the updated descriptor, and the error handling
for that in turn leaves the ring buffer in an inconsistent state.

Add the missing memory barrier to make sure that the descriptor is read
after the head pointer to address the root cause of the corruption while
fixing up the error handling in case there are ever any (ordering) bugs
on the device side.

Note that the READ_ONCE() are only needed to avoid compiler mischief in
case the ring-buffer helpers are ever inlined.

Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41

Fixes: d5c65159 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218623
Link: https://lore.kernel.org/20250310010217.3845141-3-quic_miaoqing@quicinc.com


Cc: Miaoqing Pan <quic_miaoqing@quicinc.com>
Cc: stable@vger.kernel.org	# 5.6
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Miaoqing Pan <quic_miaoqing@quicinc.com>
Tested-by: Steev Klimaszewski <steev@kali.org>
Tested-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
Tested-by: Clayton Craft <clayton@craftyguy.net>
Link: https://patch.msgid.link/20250321094916.19098-1-johan+linaro@kernel.org


Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>