From 45617b727e280cac384a28ae3d96145e066e6197 Mon Sep 17 00:00:00 2001

From: Reid Wahl <nrwahl@protonmail.com>

Date: Fri, 3 Feb 2023 12:08:57 -0800

Subject: [PATCH 01/02] Fix: fencer: Prevent double g_source_remove of op_timer_one

QE observed a rarely reproducible core dump in the fencer during

Pacemaker shutdown, in which we try to g_source_remove() an op timer

that's already been removed.

free_stonith_remote_op_list()

-> g_hash_table_destroy()

-> g_hash_table_remove_all_nodes()

-> clear_remote_op_timers()

-> g_source_remove()

-> crm_glib_handler()

-> "Source ID 190 was not found when attempting to remove it"

The likely cause is that request_peer_fencing() doesn't set

op->op_timer_one to 0 after calling g_source_remove() on it, so if that

op is still in the stonith_remote_op_list at shutdown with the same

timer, clear_remote_op_timers() tries to remove the source for

op_timer_one again.

There are only five locations that call g_source_remove() on a

remote_fencing_op_t timer.

* Three of them are in clear_remote_op_timers(), which first 0-checks

  the timer and then sets it to 0 after g_source_remove().

* One is in remote_op_query_timeout(), which does the same.

* The last is the one we fix here in request_peer_fencing().

I don't know all the conditions of QE's test scenario at this point.

What I do know:

* have-watchdog=true

* stonith-watchdog-timeout=10

* no explicit topology

* fence agent script is missing for the configured fence device

* requested fencing of one node

* cluster shutdown

Fixes RHBZ2166967

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>

---

 daemons/fenced/fenced_remote.c | 1 +

 1 file changed, 1 insertion(+)

diff --git a/daemons/fenced/fenced_remote.c b/daemons/fenced/fenced_remote.c

index d61b5bd..b7426ff 100644

--- a/daemons/fenced/fenced_remote.c

+++ b/daemons/fenced/fenced_remote.c

@@ -1825,6 +1825,7 @@ request_peer_fencing(remote_fencing_op_t *op, peer_device_info_t *peer)

         op->state = st_exec;

         if (op->op_timer_one) {

             g_source_remove(op->op_timer_one);

+            op->op_timer_one = 0;

         }

         if (!((stonith_watchdog_timeout_ms > 0)

-- 

2.31.1

From 0291db4750322ec7f01ae6a4a2a30abca9d8e19e Mon Sep 17 00:00:00 2001

From: Reid Wahl <nrwahl@protonmail.com>

Date: Wed, 15 Feb 2023 22:30:27 -0800

Subject: [PATCH 02/02] Fix: fencer: Avoid double source remove of op_timer_total

remote_op_timeout() returns G_SOURCE_REMOVE, which tells GLib to remove

the source from the main loop after returning. Currently this function

is used as the callback only when creating op->op_timer_total.

If we don't set op->op_timer_total to 0 before returning from

remote_op_timeout(), then we can get an assertion and core dump from

GLib when the op's timers are being cleared (either during op

finalization or during fencer shutdown). This is because

clear_remote_op_timers() sees that op->op_timer_total != 0 and tries to

remove the source, but the source has already been removed.

Note that we're already (correctly) zeroing op->op_timer_one and

op->query_timeout as appropriate in their respective callback functions.

Fortunately, GLib doesn't care whether the source has already been

removed before we return G_SOURCE_REMOVE from a callback. So it's safe

to call finalize_op() (which removes all the op's timer sources) from

within a callback.

Fixes RHBZ#2166967

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>

---

 daemons/fenced/fenced_remote.c | 2 ++

 1 file changed, 2 insertions(+)

diff --git a/daemons/fenced/fenced_remote.c b/daemons/fenced/fenced_remote.c

index b7426ff88..adea3d7d8 100644

--- a/daemons/fenced/fenced_remote.c

+++ b/daemons/fenced/fenced_remote.c

@@ -718,6 +718,8 @@ remote_op_timeout(gpointer userdata)

 {

     remote_fencing_op_t *op = userdata;

+    op->op_timer_total = 0;

+

     if (op->state == st_done) {

         crm_debug("Action '%s' targeting %s for client %s already completed "

                   CRM_XS " id=%.8s",

-- 

2.39.0