From 9ff6fde86fd27a0c733c01114eb0d46bd3a33fb7 Mon Sep 17 00:00:00 2001
From: Daniel Mack <daniel@zonque.org>
Date: Tue, 10 Apr 2018 19:35:58 +0200
Subject: [PATCH] wcn36xx: use READ_ONCE() to access desc->ctrl
Git-commit: 9ff6fde86fd27a0c733c01114eb0d46bd3a33fb7
Patch-mainline: v4.18-rc1
References: FATE#326906
When accessing shared memory to check for the stat of submitted
descriptors, make sure to use READ_ONCE(). This will guarantee the
compiler treats these memory locations as volatile and doesn't apply
any caching.
While this doesn't fix any particular problem I ran into, it's best
practice to do it this way.
Note that this patch also removes the superflous extra condition check
in the do-while loop in reap_tx_dxes(), as the loop will break
instantly anyway in that case.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/wireless/ath/wcn36xx/dxe.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/net/wireless/ath/wcn36xx/dxe.c b/drivers/net/wireless/ath/wcn36xx/dxe.c
index a6702ada13d3..bd2b946a65c9 100644
--- a/drivers/net/wireless/ath/wcn36xx/dxe.c
+++ b/drivers/net/wireless/ath/wcn36xx/dxe.c
@@ -368,7 +368,7 @@ static void reap_tx_dxes(struct wcn36xx *wcn, struct wcn36xx_dxe_ch *ch)
spin_lock_irqsave(&ch->lock, flags);
ctl = ch->tail_blk_ctl;
do {
- if (ctl->desc->ctrl & WCN36xx_DXE_CTRL_VLD)
+ if (READ_ONCE(ctl->desc->ctrl) & WCN36xx_DXE_CTRL_VLD)
break;
if (ctl->skb) {
dma_unmap_single(wcn->dev, ctl->desc->src_addr_l,
@@ -387,8 +387,7 @@ static void reap_tx_dxes(struct wcn36xx *wcn, struct wcn36xx_dxe_ch *ch)
ctl->skb = NULL;
}
ctl = ctl->next;
- } while (ctl != ch->head_blk_ctl &&
- !(ctl->desc->ctrl & WCN36xx_DXE_CTRL_VLD));
+ } while (ctl != ch->head_blk_ctl);
ch->tail_blk_ctl = ctl;
spin_unlock_irqrestore(&ch->lock, flags);
@@ -530,7 +529,7 @@ static int wcn36xx_rx_handle_packets(struct wcn36xx *wcn,
int_mask = WCN36XX_DXE_INT_CH3_MASK;
}
- while (!(dxe->ctrl & WCN36xx_DXE_CTRL_VLD)) {
+ while (!(READ_ONCE(dxe->ctrl) & WCN36xx_DXE_CTRL_VLD)) {
skb = ctl->skb;
dma_addr = dxe->dst_addr_l;
ret = wcn36xx_dxe_fill_skb(wcn->dev, ctl, GFP_ATOMIC);
--
2.19.2