[2/4] libertas_tf: use irqsave() in USB's complete callback

[2/4] libertas_tf: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

I am removing the
	BUG_ON(!in_interrupt());

check because it serves no purpose. Running the completion callback in
BH context makes in_interrupt() still return true but the interrupts
could be enabled. The important part is that ->driver_lock is acquired
with disabled interrupts which is the case now.

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/net/wireless/marvell/libertas_tf/if_usb.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas_tf/if_usb.c b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
index 5153922e7ce1..e92fc5001171 100644
--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
@@ -603,6 +603,8 @@ static inline void process_cmdrequest(int recvlength, uint8_t *recvbuff,
 				      struct if_usb_card *cardp,
 				      struct lbtf_private *priv)
 {
+	unsigned long flags;
+
 	if (recvlength > LBS_CMD_BUFFER_SIZE) {
 		lbtf_deb_usbd(&cardp->udev->dev,
 			     "The receive buffer is too large\n");
@@ -610,14 +612,12 @@ static inline void process_cmdrequest(int recvlength, uint8_t *recvbuff,
 		return;
 	}
 
-	BUG_ON(!in_interrupt());
-
-	spin_lock(&priv->driver_lock);
+	spin_lock_irqsave(&priv->driver_lock, flags);
 	memcpy(priv->cmd_resp_buff, recvbuff + MESSAGE_HEADER_LEN,
 	       recvlength - MESSAGE_HEADER_LEN);
 	kfree_skb(skb);
 	lbtf_cmd_response_rx(priv);
-	spin_unlock(&priv->driver_lock);
+	spin_unlock_irqrestore(&priv->driver_lock, flags);
 }
 
 /**

[2/4] libertas_tf: use irqsave() in USB's complete callback

[Kalle Valo]

Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:

> The USB completion callback does not disable interrupts while acquiring
> the lock. We want to remove the local_irq_disable() invocation from
> __usb_hcd_giveback_urb() and therefore it is required for the callback
> handler to disable the interrupts while acquiring the lock.
> The callback may be invoked either in IRQ or BH context depending on the
> USB host controller.
> Use the _irqsave() variant of the locking primitives.
> 
> I am removing the
> 	BUG_ON(!in_interrupt());
> 
> check because it serves no purpose. Running the completion callback in
> BH context makes in_interrupt() still return true but the interrupts
> could be enabled. The important part is that ->driver_lock is acquired
> with disabled interrupts which is the case now.
> 
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

3 patches applied to wireless-drivers-next.git, thanks.

fc75122fabb5 libertas_tf: use irqsave() in USB's complete callback
a3128feef6d5 libertas: use irqsave() in USB's complete callback
81454b8405f2 zd1211rw: use irqsave() in USB's complete callback