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From: Arnd Bergmann <arnd@bergmann-dalldorf.de>
To: Patrick Mochel <mochel@osdl.org>
Subject: [patch] bad locking in {driver,bus}_for_each_{drv,dev}
Date: Thu, 13 Jun 2002 19:16:31 +0200
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Cc: linux-kernel@vger.kernel.org, Arnd Bergmann <arndb@de.ibm.com>
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Hi,

I just ran in a deadlock in driver_for_each_dev, where read_unlock 
was called without the lock being held. The patch below avoids the
problem there and in the other two places I found it.

	Arnd <><

--- linux-2.5.21/drivers/base/driver.c  Thu Jun 13 19:00:48 2002
+++ drivers/base/driver.c       Thu Jun 13 19:01:25 2002
@@ -31,6 +31,7 @@
                dev = next;
                if ((error = callback(dev,data))) {
                        put_device(dev);
+                       read_lock(&drv->lock);
                        break;
                }
                read_lock(&drv->lock);
--- linux-2.5.21/drivers/base/bus.c     Thu Jun 13 19:05:25 2002
+++ drivers/base/bus.c  Thu Jun 13 19:06:01 2002
@@ -61,6 +61,7 @@
                dev = next;
                if ((error = callback(dev,data))) {
                        put_device(dev);
+                       read_lock(&bus->lock);
                        break;
                }
                read_lock(&bus->lock);
@@ -96,6 +97,7 @@
                drv = next;
                if ((error = callback(drv,data))) {
                        put_driver(drv);
+                       read_lock(&bus->lock);
                        break;
                }
                read_lock(&bus->lock);
-
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