From: Shrenik Shikhare <shrenik@xxxxxxxxxxx>
There is a race condition for acquiring rx_proc_lock between
rx worker thread and USB RX data interrupt
(mwifiex_usb_rx_complete):
1. USB receives an RX data interrupt, queues rx_work
2. rx_work empties rx_data_q, tries to acquire rx_proc_lock (to
clear rx_processing flag)
3. While #2 is yet to acquire rx_proc_lock, driver receives
continuous RX data interupts(mwifiex_usb_rx_complete)
3. For each interrupt at #3, driver acquires rx_proc_lock(it gets
the lock since it is in interrupt context), tries to queue
rx_work, but fails to do so since rx_processing is still set(#2)
4. When rx_pending exceeds HIGH_RX_PENDING, driver stops
submitting URBs back to USB subsystem and thus firmware stops
uploading RX data to driver
5. Now finally #2 will acquire rx_proc_lock, but because of #4,
there are no further triggers to schedule rx_work again
The above scenario occurs in some platforms where the RX
processing is comparitively slower. This results in RX stall in
driver, command/TX timeouts in firmware. The above scenario is
introduced after commit c7dbdcb2a4e1
("mwifiex: schedule rx_work on RX interrupt for USB")
To fix this set a new more_rx_task_flag whenever RX data callback
is trying to schedule rx_work but rx_processing is not yet
cleared. This will let the current rx_work(which was waiting for
rx_proc_lock) to loopback and process newly arrived RX packets.
Signed-off-by: Cathy Luo <cluo@xxxxxxxxxxx>
Signed-off-by: Ganapathi Bhat <gbhat@xxxxxxxxxxx>
---
drivers/net/wireless/marvell/mwifiex/main.c | 10 +++++++++-
drivers/net/wireless/marvell/mwifiex/main.h | 1 +
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
index 6e6e1a7..ea87c7c 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -163,6 +163,7 @@ void mwifiex_queue_main_work(struct mwifiex_adapter *adapter)
spin_lock_irqsave(&adapter->main_proc_lock, flags);
if (adapter->mwifiex_processing) {
adapter->more_task_flag = true;
+ adapter->more_rx_task_flag = true;
spin_unlock_irqrestore(&adapter->main_proc_lock, flags);
} else {
spin_unlock_irqrestore(&adapter->main_proc_lock, flags);
@@ -177,6 +178,7 @@ void mwifiex_queue_rx_work(struct mwifiex_adapter *adapter)
spin_lock_irqsave(&adapter->rx_proc_lock, flags);
if (adapter->rx_processing) {
+ adapter->more_rx_task_flag = true;
spin_unlock_irqrestore(&adapter->rx_proc_lock, flags);
} else {
spin_unlock_irqrestore(&adapter->rx_proc_lock, flags);
@@ -193,13 +195,14 @@ static int mwifiex_process_rx(struct mwifiex_adapter *adapter)
spin_lock_irqsave(&adapter->rx_proc_lock, flags);
if (adapter->rx_processing || adapter->rx_locked) {
+ adapter->more_rx_task_flag = true;
spin_unlock_irqrestore(&adapter->rx_proc_lock, flags);
goto exit_rx_proc;
} else {
adapter->rx_processing = true;
spin_unlock_irqrestore(&adapter->rx_proc_lock, flags);
}
-
+rx_process_start:
/* Check for Rx data */
while ((skb = skb_dequeue(&adapter->rx_data_q))) {
atomic_dec(&adapter->rx_pending);
@@ -221,6 +224,11 @@ static int mwifiex_process_rx(struct mwifiex_adapter *adapter)
}
}
spin_lock_irqsave(&adapter->rx_proc_lock, flags);
+ if (adapter->more_rx_task_flag) {
+ adapter->more_rx_task_flag = false;
+ spin_unlock_irqrestore(&adapter->rx_proc_lock, flags);
+ goto rx_process_start;
+ }
adapter->rx_processing = false;
spin_unlock_irqrestore(&adapter->rx_proc_lock, flags);
diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h
index 66ba95c..242e05e 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.h
+++ b/drivers/net/wireless/marvell/mwifiex/main.h
@@ -891,6 +891,7 @@ struct mwifiex_adapter {
spinlock_t main_proc_lock;
u32 mwifiex_processing;
u8 more_task_flag;
+ u8 more_rx_task_flag;
u16 tx_buf_size;
u16 curr_tx_buf_size;
/* sdio single port rx aggregation capability */
--
1.9.1
