linux-kernel - [PATCH] usb: gadget: composite: unlock spinlock before usb_gadget

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Message-id: <1402658893-4809-1-git-send-email-r.baldyga@samsung.com>
Date:	Fri, 13 Jun 2014 13:28:13 +0200
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	balbi@...com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
	andrzej.p@...sung.com, Robert Baldyga <r.baldyga@...sung.com>
Subject: [PATCH] usb: gadget: composite: unlock spinlock before
 usb_gadget_disconnect()

usb_gadget_disconnect() shouldn't be called under spinlock to avoid
spinlock recursion. Function usb_gadget_disconnect() calls pullup(),
which is callback from UDC driver, usually calling composite_disconnect().
This function wants to lock spinlock used in usb_function_deactivate()
causing spinlock recursion.

Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
---
 drivers/usb/gadget/composite.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index d41103e..77cae4b 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -260,8 +260,11 @@ int usb_function_deactivate(struct usb_function *function)
 
 	spin_lock_irqsave(&cdev->lock, flags);
 
-	if (cdev->deactivations == 0)
+	if (cdev->deactivations == 0) {
+		spin_unlock_irqrestore(&cdev->lock, flags);
 		status = usb_gadget_disconnect(cdev->gadget);
+		spin_lock_irqsave(&cdev->lock, flags);
+	}
 	if (status == 0)
 		cdev->deactivations++;
 
-- 
1.9.1

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