On 02/28/14 18:32, Hannes Reinecke wrote: > On 02/28/2014 09:49 AM, Junichi Nomura wrote: >> On 02/27/14 16:30, Hannes Reinecke wrote: >>> activate_path() is run without a lock, so the path might be >>> set to failed before activate_path() had a chance to run. >>> >>> Signed-off-by: Hannes Reinecke <hare@xxxxxxx> >>> --- >>> drivers/md/dm-mpath.c | 7 +++++-- >>> 1 file changed, 5 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c >>> index 0a40fa9..22e7365 100644 >>> --- a/drivers/md/dm-mpath.c >>> +++ b/drivers/md/dm-mpath.c >>> @@ -1196,8 +1196,11 @@ static void activate_path(struct work_struct *work) >>> struct pgpath *pgpath = >>> container_of(work, struct pgpath, activate_path.work); >>> >>> - scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev), >>> - pg_init_done, pgpath); >>> + if (pgpath->is_active) >>> + scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev), >>> + pg_init_done, pgpath); >>> + else >>> + pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED); >> >> Hi Hannes, >> >> What problem are you going to fix with this? >> It is still possible that the path is set to failed just after >> "if (pgpath->is_active)" and before "scsi_dh_activate". >> > activate_path() is run from a workqueue, so there is a race window > between the check ->is_active in __pg_init_all_paths() and the time > the scsi_dh_activate() is executed. And as activate_path)() is run > without any locks we don't have any synchronization with fail_path(). > So it's well possible that a path gets failed in between > __pg_init_all_paths() and activate_paths(). What I pointed is that your patch makes the window very small but doesn't close it. If the race is a problem, this patch doesn't fix the problem. -- Jun'ichi Nomura, NEC Corporation -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
