[PATCH] usb: gadget: u_ether: synchronize with transmit when stopping queue

[Vicentiu Neagoe]

From: Jeff Westfahl <jeff.westfahl@xxxxxx>

When disconnecting, it's possible that another thread has already made it
into eth_start_xmit before we call netif_stop_queue. This can lead to a
crash as eth_start_xmit tries to use resources that gether_disconnect is
freeing. Use netif_tx_lock/unlock around netif_stop_queue to ensure no
threads are executing during the remainder of gether_disconnect.

Signed-off-by: Jeff Westfahl <jeff.westfahl@xxxxxx>
Tested-by: Jaeden Amero <jaeden.amero@xxxxxx>
---
 drivers/usb/gadget/u_ether.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
index b7d4f82..085a76e 100644
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -1120,7 +1120,10 @@ void gether_disconnect(struct gether *link)
 
 	DBG(dev, "%s\n", __func__);
 
+	netif_tx_lock(dev->net);
 	netif_stop_queue(dev->net);
+	netif_tx_unlock(dev->net);
+
 	netif_carrier_off(dev->net);
 
 	/* disable endpoints, forcing (synchronous) completion
-- 
1.7.9.5

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