On Tue, Jan 07 2014 at 1:00pm -0500, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > On Tue, 7 Jan 2014, Linus Torvalds wrote: > > > This looks completely broken to me. You do a "kobject_put()" and then > > after you've dropped that last use, you wait for the completion of > > something that may already have been free'd. > > > > Wtf? Am I missing something? > > > > Linus > > It is correct. The release method dm_kobject_release doesn't free the > kobject. It just signals the completion and returns. > > This is the sequence of operations: > * call kobject_put > * wait until all users stop using the kobject, when it happens the release > method is called > * the release method signals the completion and returns > * the unload code that waits on the completion continues > * the unload code frees the mapped_device structure that contains the > kobject > > Using kobject this way avoids the module unload race that was mentioned at > the beginning of this thread. I've staged your patch in linux-next for 3.14, see: http://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=af7b1e5c767fc895788c971c8f4686402ac8344f -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
