On Sun, Dec 15, 2013 at 08:55:27AM +0100, Levente Kurusa wrote: > On 12/14/2013 06:24 PM, Greg Kroah-Hartman wrote: > > On Fri, Dec 13, 2013 at 01:42:05PM -0700, Bjorn Helgaas wrote: > >> [+cc Greg] > >> > >> On Fri, Dec 13, 2013 at 12:22 PM, Levente Kurusa <le...@linux.com> wrote: > >>> Hi, > >>> > >>> This is just the beginning of patchset-set that aims to fix possible > >>> problems caused by not calling put_device() if device_register() fails. > >>> > >>> The root cause for the need to call put_device() is that the underlying > >>> kobject still has a reference count of 1. Thus, device.release() will not > >>> be called and the device will just sit there waiting for a put_device(). > >>> Adding the put_device() also removes the need for the call to kfree() as > >>> most > >>> release functions already call kfree() on the container of the device. > >>> > >>> While these have not been experienced, they are potential issues and thus > >>> they need to be fixed. Also, they are a few more files that have the same > >>> kind of issue, those will be fixed if these are accepted. > >> > >> Thanks for doing this. This is the sort of mistake that just gets > >> copied everywhere, so fixing the examples in the tree will help > >> prevent the problem from spreading more. > >> > >> I don't know if there's really value in having device_register() > >> return an error but rely on the caller to do the put_device(). Are > >> there cases where the caller still needs the struct device even if > >> device_register() fails? E.g., could we do something like this > >> instead (I know some callers would also require corresponding changes > >> to avoid double puts): > > There are cases where it is needed. There are quite a few files which > when device_register() fails, the driver print an error messages.
That shouldn't be needed, and can be removed. > IIRC, there are also a few where the device is also unregistered from > the specific subsystem's core. Do you have a specific example of this? This should happen in the release function of the device already, not in some other code. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
