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SubjectRe: Incorrect uses of get_driver()/put_driver()
On Mon, Jan 09, 2012 at 12:35:09PM -0500, Alan Stern wrote:
> The get_driver() and put_driver() routines in the device core are not
> documented well, and what they really do is quite different from what
> people might think they do. In particular, get_driver() does not
> prevent a driver from being unregistered or unloaded -- the API which
> comes closest to doing that is try_module_get().
> In fact, get_driver() and put_driver() are pretty much useless for
> normal purposes, and Dmitry and I have been discussing getting rid of
> them entirely. But first we need to make sure that doing so won't mess
> anything up.
> The purpose of this email is to check with the maintainers of the
> various drivers that seem to be using these routines in questionable
> ways, to make sure nothing will go wrong. Here are the places we have
> identified:
> lib/dma-debug.c:173: drv = get_driver(dev->driver);
> lib/dma-debug.c:188: put_driver(drv);
> Joerg, these calls don't seem to do anything, as far as I can tell.
> Is there any reason to keep them?
> drivers/pci/xen-pcifront.c:596: if (get_driver(&pdrv->driver)) {
> drivers/pci/xen-pcifront.c:626: put_driver(&pdrv->driver);
> Konrad, these calls don't seem to do anything either.

Looks like they should be replaced with the try_module_get() equivalant
for the 'struct pci_driver'? Is there such one?

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