On Fri, 2018-02-09 at 23:07 -0600, Benjamin Marzinski wrote:
> If setup_multipath() is called before the waiter thread has started,
> there is a window where a dm event can occur between when
> setup_multipath() updates the device state and when the waiter thread
> starts waiting for new events, causing the new event to be missed and
> the multipath device to not get updated.
>
> Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
The window will be still there, but smaller than before.
Reviewed-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> multipathd/main.c | 37 ++++++++++++++++++++-----------------
> 1 file changed, 20 insertions(+), 17 deletions(-)
>
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 94b2406..efc39d7 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -321,7 +321,7 @@ set_multipath_wwid (struct multipath * mpp)
> }
>
> static int
> -update_map (struct multipath *mpp, struct vectors *vecs)
> +update_map (struct multipath *mpp, struct vectors *vecs, int
> new_map)
> {
> int retries = 3;
> char params[PARAMS_SIZE] = {0};
> @@ -351,6 +351,12 @@ retry:
> dm_lib_release();
>
> fail:
> + if (new_map && (retries < 0 || start_waiter_thread(mpp,
> vecs))) {
> + condlog(0, "%s: failed to create new map", mpp-
> >alias);
> + remove_map(mpp, vecs, 1);
> + return 1;
> + }
> +
> if (setup_multipath(vecs, mpp))
> return 1;
>
> @@ -395,12 +401,9 @@ add_map_without_path (struct vectors *vecs, char
> *alias)
>
> vector_set_slot(vecs->mpvec, mpp);
>
> - if (update_map(mpp, vecs) != 0) /* map removed */
> + if (update_map(mpp, vecs, 1) != 0) /* map removed */
> return NULL;
>
> - if (start_waiter_thread(mpp, vecs))
> - goto out;
> -
> return mpp;
> out:
> remove_map(mpp, vecs, PURGE_VEC);
> @@ -554,7 +557,7 @@ ev_add_map (char * dev, char * alias, struct
> vectors * vecs)
> if (mpp->wait_for_udev > 1) {
> condlog(2, "%s: performing delayed actions",
> mpp->alias);
> - if (update_map(mpp, vecs))
> + if (update_map(mpp, vecs, 0))
> /* setup multipathd removed the map
> */
> return 1;
> }
> @@ -865,6 +868,11 @@ retry:
> }
> dm_lib_release();
>
> + if ((mpp->action == ACT_CREATE ||
> + (mpp->action == ACT_NOTHING && start_waiter && !mpp-
> >waiter)) &&
> + start_waiter_thread(mpp, vecs))
> + goto fail_map;
> +
> /*
> * update our state from kernel regardless of create or
> reload
> */
> @@ -873,11 +881,6 @@ retry:
>
> sync_map_state(mpp);
>
> - if ((mpp->action == ACT_CREATE ||
> - (mpp->action == ACT_NOTHING && start_waiter && !mpp-
> >waiter)) &&
> - start_waiter_thread(mpp, vecs))
> - goto fail_map;
> -
> if (retries >= 0) {
> condlog(2, "%s [%s]: path added to devmap %s",
> pp->dev, pp->dev_t, mpp->alias);
> @@ -1479,7 +1482,8 @@ missing_uev_wait_tick(struct vectors *vecs)
> if (mpp->wait_for_udev && --mpp->uev_wait_tick <= 0)
> {
> timed_out = 1;
> condlog(0, "%s: timeout waiting on creation
> uevent. enabling reloads", mpp->alias);
> - if (mpp->wait_for_udev > 1 &&
> update_map(mpp, vecs)) {
> + if (mpp->wait_for_udev > 1 &&
> + update_map(mpp, vecs, 0)) {
> /* update_map removed map */
> i--;
> continue;
> @@ -1511,7 +1515,7 @@ ghost_delay_tick(struct vectors *vecs)
> condlog(0, "%s: timed out waiting for active
> path",
> mpp->alias);
> mpp->force_udev_reload = 1;
> - if (update_map(mpp, vecs) != 0) {
> + if (update_map(mpp, vecs, 0) != 0) {
> /* update_map removed map */
> i--;
> continue;
> @@ -2169,14 +2173,13 @@ configure (struct vectors * vecs)
> * start dm event waiter threads for these new maps
> */
> vector_foreach_slot(vecs->mpvec, mpp, i) {
> - if (setup_multipath(vecs, mpp)) {
> - i--;
> - continue;
> - }
> if (start_waiter_thread(mpp, vecs)) {
> remove_map(mpp, vecs, 1);
> i--;
> + continue;
> }
> + if (setup_multipath(vecs, mpp))
> + i--;
> }
> return 0;
> }
--
Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
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