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Date: Mon, 25 Jul 2005 12:50:46 -0700
From: Pete Zaitcev <zaitcev@redhat.com>
To: <marcelo.tosatti@cyclades.com>
Cc: zaitcev@redhat.com, linux-kernel@vger.kernel.org
Subject: usb: printer double up()
Message-Id: <20050725125046.36398aae.zaitcev@redhat.com>
Organization: Red Hat, Inc.
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Doing a double up() is actually safe in Linux, but still, it's a bug.
This fix is present in 2.6.13-rc3.

By Domen Puncer <domen@coderock.org>
up(&usblp->sem) was called twice in a row in this code path.

--- linux-2.4.31/drivers/usb/printer.c	2004-08-10 13:43:36.000000000 -0700
+++ linux-2.4.31-usb/drivers/usb/printer.c	2005-06-05 11:21:12.000000000 -0700
@@ -740,6 +740,7 @@ static ssize_t usblp_read(struct file *f
 				schedule();
 			} else {
 				set_current_state(TASK_RUNNING);
+				down (&usblp->sem);
 				break;
 			}
 			down (&usblp->sem);