Re: [PATCH] wcn36xx: add proper DMA memory barriers in rx path
From: Kalle Valo <hidden>
Date: 2021-10-27 07:44:37
Also in:
linux-arm-msm, linux-wireless, lkml
Benjamin Li [off-list ref] wrote:
This is essentially exactly following the dma_wmb()/dma_rmb() usage
instructions in Documentation/memory-barriers.txt.
The theoretical races here are:
1. DXE (the DMA Transfer Engine in the Wi-Fi subsystem) seeing the
dxe->ctrl & WCN36xx_DXE_CTRL_VLD write before the dxe->dst_addr_l
write, thus performing DMA into the wrong address.
2. CPU reading dxe->dst_addr_l before DXE unsets dxe->ctrl &
WCN36xx_DXE_CTRL_VLD. This should generally be harmless since DXE
doesn't write dxe->dst_addr_l (no risk of freeing the wrong skb).
Fixes: 8e84c2582169 ("wcn36xx: mac80211 driver for Qualcomm WCN3660/WCN3680 hardware")
Signed-off-by: Benjamin Li <redacted>
Signed-off-by: Kalle Valo <redacted>Patch applied to ath-next branch of ath.git, thanks. 9bfe38e064af wcn36xx: add proper DMA memory barriers in rx path -- https://patchwork.kernel.org/project/linux-wireless/patch/20211023001528.3077822-1-benl@squareup.com/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches