[PATCH 1/2] mwifiex: schedule rx_work on RX interrupt for USB

[Ganapathi Bhat <gbhat@marvell.com>]

From: Shrenik Shikhare <shrenik@marvell.com>

There is race for data_received flag between main thread and
RX data interrupt(mwifiex_usb_rx_complete()):
1. USB received an RX data interrupt, set data_received flag
2. main thread checks data_received, if set queues rx_work
3. rx worker thread independently start processing rx_data_q
4. rx work exits (once rx_data_q is empty)
5. main thread resets the data_received flag(after #2)
6. Now at the corner case there will be high RX data interrupts
between #4 and #5
7. Driver stops submitting URBs to firmware, once rx_pending
exceeds HIGH_RX_PENDING
8. The flag data_received(cleared in #5) will remain unset since
there will be no interrupts from firmware to set it(after #7)

Above scenario causes RX stall in driver, which will finally
result in command/TX timeouts in firmware.

As a fix, queue rx_work directly in mwifiex_usb_rx_complete()
callback, instead in the main thread. This removes dependency
of RX processing on data_received flag.

Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
---
 drivers/net/wireless/marvell/mwifiex/main.c | 7 ++++---
 drivers/net/wireless/marvell/mwifiex/main.h | 1 +
 drivers/net/wireless/marvell/mwifiex/usb.c  | 2 ++
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
index 12e7399..6e6e1a7 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -171,7 +171,7 @@ void mwifiex_queue_main_work(struct mwifiex_adapter *adapter)
 }
 EXPORT_SYMBOL_GPL(mwifiex_queue_main_work);
 
-static void mwifiex_queue_rx_work(struct mwifiex_adapter *adapter)
+void mwifiex_queue_rx_work(struct mwifiex_adapter *adapter)
 {
 	unsigned long flags;
 
@@ -183,6 +183,7 @@ static void mwifiex_queue_rx_work(struct mwifiex_adapter *adapter)
 		queue_work(adapter->rx_workqueue, &adapter->rx_work);
 	}
 }
+EXPORT_SYMBOL_GPL(mwifiex_queue_rx_work);
 
 static int mwifiex_process_rx(struct mwifiex_adapter *adapter)
 {
@@ -283,10 +284,10 @@ int mwifiex_main_process(struct mwifiex_adapter *adapter)
 				mwifiex_process_hs_config(adapter);
 			if (adapter->if_ops.process_int_status)
 				adapter->if_ops.process_int_status(adapter);
+			if (adapter->rx_work_enabled && adapter->data_received)
+				mwifiex_queue_rx_work(adapter);
 		}
 
-		if (adapter->rx_work_enabled && adapter->data_received)
-			mwifiex_queue_rx_work(adapter);
 
 		/* Need to wake up the card ? */
 		if ((adapter->ps_state == PS_STATE_SLEEP) &&
diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h
index 6b5539b..66ba95c 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.h
+++ b/drivers/net/wireless/marvell/mwifiex/main.h
@@ -1667,6 +1667,7 @@ u8 mwifiex_adjust_data_rate(struct mwifiex_private *priv,
 void mwifiex_upload_device_dump(struct mwifiex_adapter *adapter);
 void *mwifiex_alloc_dma_align_buf(int rx_len, gfp_t flags);
 void mwifiex_queue_main_work(struct mwifiex_adapter *adapter);
+void mwifiex_queue_rx_work(struct mwifiex_adapter *adapter);
 int mwifiex_get_wakeup_reason(struct mwifiex_private *priv, u16 action,
 			      int cmd_type,
 			      struct mwifiex_ds_wakeup_reason *wakeup_reason);
diff --git a/drivers/net/wireless/marvell/mwifiex/usb.c b/drivers/net/wireless/marvell/mwifiex/usb.c
index 4bc2448..d20fda1 100644
--- a/drivers/net/wireless/marvell/mwifiex/usb.c
+++ b/drivers/net/wireless/marvell/mwifiex/usb.c
@@ -144,6 +144,8 @@ static int mwifiex_usb_recv(struct mwifiex_adapter *adapter,
 		skb_queue_tail(&adapter->rx_data_q, skb);
 		adapter->data_received = true;
 		atomic_inc(&adapter->rx_pending);
+		if (adapter->rx_work_enabled)
+			mwifiex_queue_rx_work(adapter);
 		break;
 	default:
 		mwifiex_dbg(adapter, ERROR,
-- 
1.9.1