brcmfmac: block the correct flowring when backup queue overflow

brcmf_flowring_block blocks the last active flowring under the same
interface instead of the one provided by caller. This could lead to a
dead lock of netif stop if there are more than one flowring under the
interface and the traffic is high enough so brcmf_flowring_enqueue can
not unblock the ring right away.
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/brcm80211/brcmfmac/flowring.c

@@ -194,11 +194,15 @@ static void brcmf_flowring_block(struct brcmf_flowring *flow, u8 flowid,
 	spin_lock_irqsave(&flow->block_lock, flags);
 
 	ring = flow->rings[flowid];
+	if (ring->blocked == blocked) {
+		spin_unlock_irqrestore(&flow->block_lock, flags);
+		return;
+	}
 	ifidx = brcmf_flowring_ifidx_get(flow, flowid);
 
 	currently_blocked = false;
 	for (i = 0; i < flow->nrofrings; i++) {
-		if (flow->rings[i]) {
+		if ((flow->rings[i]) && (i != flowid)) {
 			ring = flow->rings[i];
 			if ((ring->status == RING_OPEN) &&
 			    (brcmf_flowring_ifidx_get(flow, i) == ifidx)) {
@@ -209,8 +213,8 @@ static void brcmf_flowring_block(struct brcmf_flowring *flow, u8 flowid,
 			}
 		}
 	}
-	ring->blocked = blocked;
-	if (currently_blocked == blocked) {
+	flow->rings[flowid]->blocked = blocked;
+	if (currently_blocked) {
 		spin_unlock_irqrestore(&flow->block_lock, flags);
 		return;
 	}