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To: [email protected]
From: [email protected] (Linus Torvalds)
Subject: Re: device model update 2/2
Date: Thu, 6 Jun 2002 16:45:25 +0000 (UTC)
Organization: Transmeta Corporation
Message-ID: <[email protected]>
In-Reply-To: <A183DF60AC72D5119B990002A5749CB301E9C106@ROMADG-MAIL01> <[email protected]>
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In article <[email protected]>,
Patrick Mochel <[email protected]> wrote:
>-
> /* detach from driver */
> if (dev->driver->remove)
> dev->driver->remove(dev);
> put_driver(dev->driver);
>+
>+ lock_device(dev);
>+ dev->driver = NULL;
>+ unlock_device(dev);
Code like the above just basically can _never_ be correct.
The locking just doesn't make any sense like that.
Real locking looks something like this:
lock_device(dev);
driver = dev->driver;
dev->driver = NULL;
unlock_device(dev);
if (driver->remove)
driver->remove(dev);
put_driver(driver);
together with some promise that "dev" cannot go away from under us (ie a
refcount on "dev" itself).
Linus