Messages in this thread | | | From | Oliver Neukum <> | Subject | Re: refcounting drivers' data structures used in sysfs buffers | Date | Mon, 12 Mar 2007 16:59:26 +0100 |
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Am Montag, 12. März 2007 16:42 schrieb Dmitry Torokhov: > On 3/12/07, Oliver Neukum <oneukum@suse.de> wrote: > > Am Montag, 12. März 2007 15:57 schrieb Alan Stern > > > No, you're missing the point. Let's say driver A's disconnect() is > > > called, so the driver marks its private data structure as "disconnected" > > > and does dev_set_drvdata(NULL). Then driver B is probed and bound to the > > > device, and it does its own dev_set_drvdata(). Then a user still holding > > > an open sysfs file reference for driver A calls a show() or store() > > > method. The method will do dev_get_drvdata(), receiving the pointer to > > > driver B's private data. Now you're in trouble, because A's method will > > > think it owns B's private data! > > > > Yes, I was missing the point. In consequence, drivers must not use > > dev_get_drvdata() to get their references to their private data. It's > > probably necessary to store it in struct sysfs_buffer and include that > > in the store/show callbacks. > > (The same does apply to interfaces of course) > > > > Or drivers coudl verify that they still bound to the device they are > about to operate on (psmouse does this by taking a lock on device and > then checking if driver bound is the same address as psmouse). But I'd > rather get rid of all this clutter if we could sever sysfs access > after removing corresponding attributes.
No, the call has to fail if the driver is rebound to the device.
Regards Oliver - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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