On Mon, Jun 16, 2025 at 02:59:24PM +0530, Praneesh P wrote:
On 6/5/2025 4:19 PM, Baochen Qiang wrote:
On 6/5/2025 6:00 PM, Johan Hovold wrote:
On Thu, Jun 05, 2025 at 04:41:32PM +0800, Baochen Qiang wrote:
On 6/4/2025 10:45 PM, Johan Hovold wrote:
Add the missing memory barrier to make sure that destination ring descriptors are read after the head pointers to avoid using stale data on weakly ordered architectures like aarch64.
The barrier is added to the ath12k_hal_srng_access_begin() helper for symmetry with follow-on fixes for source ring buffer corruption which will add barriers to ath12k_hal_srng_access_end().
Note that this may fix the empty descriptor issue recently worked around by commit 51ad34a47e9f ("wifi: ath12k: Add drop descriptor handling for monitor ring").
why? I would expect drunk cookies are valid in case of HAL_MON_DEST_INFO0_EMPTY_DESC, rather than anything caused by reordering.
Based on a quick look it seemed like this could possibly fall in the same category as some of the other workarounds I've spotted while looking into these ordering issues (e.g. f9fff67d2d7c ("wifi: ath11k: Fix SKB corruption in REO destination ring")).
If you say this one is clearly unrelated, I'll drop the comment.
Praneesh, could you comment here since you made that change?
Empty/Drop descriptor is intentionally issued by the hardware during backpressure scenario and is unrelated to the issue discussed in this patch series.
Thanks for confirming. I've dropped this comment in v3:
https://lore.kernel.org/lkml/20250617084402.14475-1-johan+linaro@kernel.org/
Johan