On Mon, Dec 31, 2018 at 8:52 PM Yong Wu <yong.wu@xxxxxxxxxxxx> wrote: > > DL_FLAG_AUTOREMOVE_CONSUMER/SUPPLIER means "Remove the link > automatically on consumer/supplier driver unbind", that means we should > remove whole the device_link when there is no this driver no matter what > the ref_count of the link is. > > CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx> > --- > The ref_count of our device_link normally is over 1. When the consumer > device driver is removed, whole the device_link should be removed. > Thus, I add this patch. > --- I will admit to reading about device links for the first time while reviewing this patch, but I don't really get this. Why use a kref at all if we're just going to ignore its value? For instance, I see that if you call device_link_add() with the same supplier and consumer, it uses the kref to return the same link. That machinery is broken with your change. Although I don't see any uses of it, you might also expect a supplier or consumer could do a kref_get() on the link it got back from device_link_add(), and have a reasonable expectation that the link wouldn't be freed out from under it. This would also be broken. Can you explain why your device_links normally have a reference count >1, and why those additional references can't be cleaned up in an orderly fashion? (To be honest, I don't really understand the case for the AUTOREMOVE flags at all. Is there some case where the party that set up the link can't tear it down? Or is this a way to devm_ify the link, where devm itself doesn't work because the links themselves stall out that mechanism?)
