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 <[email protected]> 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. IIRC, there are also a few where the device is also unregistered from the specific subsystem's core. -- Regards, Levente Kurusa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
