On Sat, Sep 22, 2018 at 09:39:02PM +0900, Tetsuo Handa wrote: > Hello, Ming Lei. > > I'd like to hear your comment on this patch regarding the ordering of > stopping kernel thread. > > > In order to enforce this strategy, this patch inversed > > loop_reread_partitions() and loop_unprepare_queue() in loop_clr_fd(). > > I don't know whether it breaks something, but I don't have testcases. > > Until 3.19, kthread_stop(lo->lo_thread) was called before > ioctl_by_bdev(bdev, BLKRRPART, 0) is called. > During 4.0 to 4.3, the loop module was using "kloopd" workqueue. > But since 4.4, loop_reread_partitions(lo, bdev) is called before > loop_unprepare_queue(lo) is called. And this patch is trying to change to > call loop_unprepare_queue() before loop_reread_partitions() is called. > Is there some reason we need to preserve current ordering? IMO, both the two orders are fine, and what matters is that 'lo->lo_state' is updated before loop_reread_partitions(), then any IO from loop_reread_partitions will be failed, so it shouldn't be a big deal wrt. the order between loop_reread_partitions() and loop_unprepare_queue(). Thanks, Ming
