brcm80211: fmac: fix missing completion events issue

dpc takes care of all data packets transmissions for sdio function
2. It is possible that it misses some completion events when the
traffic is heavy or it's running on a slow cpu. A linked list is
introduced to make sure dpc is invoked whenever needed.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -574,6 +574,8 @@ struct brcmf_sdio {
 
 	struct task_struct *dpc_tsk;
 	struct completion dpc_wait;
+	struct list_head dpc_tsklst;
+	spinlock_t dpc_tl_lock;
 
 	struct semaphore sdsem;
 
@@ -2594,29 +2596,58 @@ static bool brcmf_sdbrcm_dpc(struct brcmf_sdio *bus)
 	return resched;
 }
 
+static inline void brcmf_sdbrcm_adddpctsk(struct brcmf_sdio *bus)
+{
+	struct list_head *new_hd;
+	unsigned long flags;
+
+	if (in_interrupt())
+		new_hd = kzalloc(sizeof(struct list_head), GFP_ATOMIC);
+	else
+		new_hd = kzalloc(sizeof(struct list_head), GFP_KERNEL);
+	if (new_hd == NULL)
+		return;
+
+	spin_lock_irqsave(&bus->dpc_tl_lock, flags);
+	list_add_tail(new_hd, &bus->dpc_tsklst);
+	spin_unlock_irqrestore(&bus->dpc_tl_lock, flags);
+}
+
 static int brcmf_sdbrcm_dpc_thread(void *data)
 {
 	struct brcmf_sdio *bus = (struct brcmf_sdio *) data;
+	struct list_head *cur_hd, *tmp_hd;
+	unsigned long flags;
 
 	allow_signal(SIGTERM);
 	/* Run until signal received */
 	while (1) {
 		if (kthread_should_stop())
 			break;
-		if (!wait_for_completion_interruptible(&bus->dpc_wait)) {
-			/* Call bus dpc unless it indicated down
-			(then clean stop) */
-			if (bus->sdiodev->bus_if->state != BRCMF_BUS_DOWN) {
-				if (brcmf_sdbrcm_dpc(bus))
-					complete(&bus->dpc_wait);
-			} else {
+
+		if (list_empty(&bus->dpc_tsklst))
+			if (wait_for_completion_interruptible(&bus->dpc_wait))
+				break;
+
+		spin_lock_irqsave(&bus->dpc_tl_lock, flags);
+		list_for_each_safe(cur_hd, tmp_hd, &bus->dpc_tsklst) {
+			spin_unlock_irqrestore(&bus->dpc_tl_lock, flags);
+
+			if (bus->sdiodev->bus_if->state == BRCMF_BUS_DOWN) {
 				/* after stopping the bus, exit thread */
 				brcmf_sdbrcm_bus_stop(bus->sdiodev->dev);
 				bus->dpc_tsk = NULL;
 				break;
 			}
-		} else
-			break;
+
+			if (brcmf_sdbrcm_dpc(bus))
+				brcmf_sdbrcm_adddpctsk(bus);
+
+			spin_lock_irqsave(&bus->dpc_tl_lock, flags);
+			list_del(cur_hd);
+			kfree(cur_hd);
+		}
+		spin_unlock_irqrestore(&bus->dpc_tl_lock, flags);
 	}
 	return 0;
 }
@@ -2669,8 +2700,10 @@ static int brcmf_sdbrcm_bus_txdata(struct device *dev, struct sk_buff *pkt)
 	/* Schedule DPC if needed to send queued packet(s) */
 	if (!bus->dpc_sched) {
 		bus->dpc_sched = true;
-		if (bus->dpc_tsk)
+		if (bus->dpc_tsk) {
+			brcmf_sdbrcm_adddpctsk(bus);
 			complete(&bus->dpc_wait);
+		}
 	}
 
 	return ret;
@@ -3514,8 +3547,10 @@ void brcmf_sdbrcm_isr(void *arg)
 		brcmf_dbg(ERROR, "isr w/o interrupt configured!\n");
 
 	bus->dpc_sched = true;
-	if (bus->dpc_tsk)
+	if (bus->dpc_tsk) {
+		brcmf_sdbrcm_adddpctsk(bus);
 		complete(&bus->dpc_wait);
+	}
 }
 
 static bool brcmf_sdbrcm_bus_watchdog(struct brcmf_sdio *bus)
@@ -3559,8 +3594,10 @@ static bool brcmf_sdbrcm_bus_watchdog(struct brcmf_sdio *bus)
 				bus->ipend = true;
 
 				bus->dpc_sched = true;
-				if (bus->dpc_tsk)
+				if (bus->dpc_tsk) {
+					brcmf_sdbrcm_adddpctsk(bus);
 					complete(&bus->dpc_wait);
+				}
 			}
 		}
 
@@ -3897,6 +3934,8 @@ void *brcmf_sdbrcm_probe(u32 regsva, struct brcmf_sdio_dev *sdiodev)
 	}
 	/* Initialize DPC thread */
 	init_completion(&bus->dpc_wait);
+	INIT_LIST_HEAD(&bus->dpc_tsklst);
+	spin_lock_init(&bus->dpc_tl_lock);
 	bus->dpc_tsk = kthread_run(brcmf_sdbrcm_dpc_thread,
 				   bus, "brcmf_dpc");
 	if (IS_ERR(bus->dpc_tsk)) {