netdev - [PATCH 1/5] net: usb: cdc-phonet: use irqsave() in USB's complete callback

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Message-Id: <20180620193121.24967-2-bigeasy@linutronix.de>
Date:   Wed, 20 Jun 2018 21:31:17 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     netdev@...r.kernel.org
Cc:     linux-usb@...r.kernel.org, tglx@...utronix.de,
        "David S. Miller" <davem@...emloft.net>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 1/5] net: usb: cdc-phonet: use irqsave() in USB's complete callback

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.

Cc: "David S. Miller" <davem@...emloft.net>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 drivers/net/usb/cdc-phonet.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/cdc-phonet.c b/drivers/net/usb/cdc-phonet.c
index 288ecd999171..3c40312fa453 100644
--- a/drivers/net/usb/cdc-phonet.c
+++ b/drivers/net/usb/cdc-phonet.c
@@ -99,6 +99,7 @@ static void tx_complete(struct urb *req)
 	struct net_device *dev = skb->dev;
 	struct usbpn_dev *pnd = netdev_priv(dev);
 	int status = req->status;
+	unsigned long flags;
 
 	switch (status) {
 	case 0:
@@ -115,10 +116,10 @@ static void tx_complete(struct urb *req)
 	}
 	dev->stats.tx_packets++;
 
-	spin_lock(&pnd->tx_lock);
+	spin_lock_irqsave(&pnd->tx_lock, flags);
 	pnd->tx_queue--;
 	netif_wake_queue(dev);
-	spin_unlock(&pnd->tx_lock);
+	spin_unlock_irqrestore(&pnd->tx_lock, flags);
 
 	dev_kfree_skb_any(skb);
 	usb_free_urb(req);
-- 
2.17.1