tree e078e38dc658473974fb44b862d2c284fd6b45ae
parent 40e309de4dd84ba91b9e0549a5173ce13ef02c5e
author Jeff Layton <jlayton@kernel.org> 1627415232 -0400
committer Ilya Dryomov <idryomov@gmail.com> 1630615757 +0200

ceph: cancel delayed work instead of flushing on mdsc teardown

The first thing metric_delayed_work does is check mdsc->stopping,
and then return immediately if it's set. That's good since we would
have already torn down the metric structures at this point, otherwise,
but there is no locking around mdsc->stopping.

It's possible that the ceph_metric_destroy call could race with the
delayed_work, in which case we could end up with the delayed_work
accessing destroyed percpu variables.

At this point in the mdsc teardown, the "stopping" flag has already been
set, so there's no benefit to flushing the work. Move the work
cancellation in ceph_metric_destroy ahead of the percpu variable
destruction, and eliminate the flush_delayed_work call in
ceph_mdsc_destroy.

Fixes: 18f473b384a6 ("ceph: periodically send perf metrics to MDSes")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>