fs: dlm: fix mark setting deadlock
authorAlexander Aring <aahringo@redhat.com>
Mon, 1 Mar 2021 22:05:09 +0000 (17:05 -0500)
committerDavid Teigland <teigland@redhat.com>
Tue, 9 Mar 2021 14:56:42 +0000 (08:56 -0600)
commite125fbeb538e5e35a00c6c8150a5361bef34814c
tree773e7c6d5e0f382d346fbac10ba6a28307a2974f
parent92c48950b43f4a767388cf87709d8687151a641f
fs: dlm: fix mark setting deadlock

This patch fixes an deadlock issue when dlm_lowcomms_close() is called.
When dlm_lowcomms_close() is called the clusters_root.subsys.su_mutex is
held to remove configfs items. At this time we flushing (e.g.
cancel_work_sync()) the workers of send and recv workqueue. Due the fact
that we accessing configfs items (mark values), these workers will lock
clusters_root.subsys.su_mutex as well which are already hold by
dlm_lowcomms_close() and ends in a deadlock situation.

[67170.703046] ======================================================
[67170.703965] WARNING: possible circular locking dependency detected
[67170.704758] 5.11.0-rc4+ #22 Tainted: G        W
[67170.705433] ------------------------------------------------------
[67170.706228] dlm_controld/280 is trying to acquire lock:
[67170.706915] ffff9f2f475a6948 ((wq_completion)dlm_recv){+.+.}-{0:0}, at: __flush_work+0x203/0x4c0
[67170.708026]
               but task is already holding lock:
[67170.708758] ffffffffa132f878 (&clusters_root.subsys.su_mutex){+.+.}-{3:3}, at: configfs_rmdir+0x29b/0x310
[67170.710016]
               which lock already depends on the new lock.

The new behaviour adds the mark value to the node address configuration
which doesn't require to held the clusters_root.subsys.su_mutex by
accessing mark values in a separate datastructure. However the mark
values can be set now only after a node address was set which is the
case when the user is using dlm_controld.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
fs/dlm/config.c
fs/dlm/config.h
fs/dlm/lowcomms.c
fs/dlm/lowcomms.h