On Thu, Apr 11, 2019 at 12:49:23PM +0200, Martin Wilck wrote:
> pathinfo() doesn't call get_prio() if a path is down, now keeping the old
> priority value. But if a path becomes inaccessible between the state check
> and the get_prio() call, retrieving the priority will likely fail, and the
> path priority will be reset to PRIO_UNDEF. This makes it timing-dependent
> how the priority of a failed path is treated. Fix that by checking the path
> state in get_prio() if an error occurs, and not touching pp->priority if
> the path is in inaccessible state. A checker_check() call would be too
> much here, but a quick path_offline() check seems appropriate.
>
> Keep the previous behavior for the case where getting the priority fails
> although the path is apparently healthy. This is presumably a very rare
> condition, in which it seems actually wrong to preserve the old prio value.
>
I think I was to hasty in ACKing this one.
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> libmultipath/discovery.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> index 7a17911d..7d638c20 100644
> --- a/libmultipath/discovery.c
> +++ b/libmultipath/discovery.c
> @@ -1625,8 +1625,17 @@ get_prio (struct path * pp)
> old_prio = pp->priority;
> pp->priority = prio_getprio(p, pp, checker_timeout);
> if (pp->priority < 0) {
> - condlog(3, "%s: %s prio error", pp->dev, prio_name(p));
> - pp->priority = PRIO_UNDEF;
> + /* this changes pp->offline, but why not */
> + int state = path_offline(pp);
> +
> + if (state == PATH_DOWN || state == PATH_PENDING)
Since pp->priority has already been set to something less then 0, most
likely -1 (PRIO_UNDEF), this patch isn't really keeping the old
priority. Don't you want
pp->priority = old_prio;
here?
-Ben
> + condlog(3, "%s: %s prio error in state %d, keeping prio = %d",
> + pp->dev, prio_name(p), state, pp->priority);
> + else {
> + condlog(3, "%s: %s prio error in state %d",
> + pp->dev, prio_name(p), state);
> + pp->priority = PRIO_UNDEF;
> + }
> return 1;
> }
> condlog((old_prio == pp->priority ? 4 : 3), "%s: %s prio = %u",
> --
> 2.21.0
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