MDEV-23101 : SIGSEGV in lock_rec_unlock() when Galera is enabled

Remove incorrect BF (brute force) handling from lock_rec_has_to_wait_in_queue
and move condition to correct callers. Add a function to report
BF lock waits and assert if incorrect BF-BF lock wait happens.

wsrep_report_bf_lock_wait
	Add a new function to report BF lock wait.

wsrep_assert_no_bf_bf_wait
	Add a new function to check do we have a
	BF-BF wait and if we have report this case
	and assert as it is a bug.

lock_rec_has_to_wait
	Use new wsrep_assert_bf_wait to check BF-BF wait.

lock_rec_create_low
lock_table_create
	Use new function to report BF lock waits.

lock_rec_insert_by_trx_age
lock_grant_and_move_on_page
lock_grant_and_move_on_rec
	Assert that trx is not Galera as VATS is not compatible
	with Galera.

lock_rec_add_to_queue
	If there is conflicting lock in a queue make sure that
	transaction is BF.

lock_rec_has_to_wait_in_queue
	Remove incorrect BF handling. If there is conflicting
	locks in a queue all transactions must wait.

lock_rec_dequeue_from_page
lock_rec_unlock
	If there is conflicting lock make sure it is not
	BF-BF case.

lock_rec_queue_validate
	Add Galera record locking rules comment and use
	new function to report BF lock waits.

All attempts to reproduce the original assertion have been
failed. Therefore, there is no test case on this commit.

4 files changed, 30 insertions, 2 deletions

diff --git a/sql/sql_plugin_services.ic b/sql/sql_plugin_services.ic
index 20113444b64..43fe540731e 100644
--- a/sql/sql_plugin_services.ic
+++ b/sql/sql_plugin_services.ic
@@ -184,7 +184,8 @@ static struct wsrep_service_st wsrep_handler = {
   wsrep_trx_order_before,
   wsrep_unlock_rollback,
   wsrep_set_data_home_dir,
-  wsrep_thd_is_applier
+  wsrep_thd_is_applier,
+  wsrep_report_bf_lock_wait
 };
 
 static struct thd_specifics_service_st thd_specifics_handler=
diff --git a/sql/wsrep_dummy.cc b/sql/wsrep_dummy.cc
index d8ab86c25f2..53941c06892 100644
--- a/sql/wsrep_dummy.cc
+++ b/sql/wsrep_dummy.cc
@@ -1,4 +1,4 @@
-/* Copyright (C) 2014 SkySQL Ab.
+/* Copyright (C) 2014, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -154,3 +154,7 @@ void wsrep_log(void (*)(const char *, ...), const char *, ...)
 
 my_bool wsrep_thd_is_applier(MYSQL_THD thd)
 { return false; }
+
+void wsrep_report_bf_lock_wait(MYSQL_THD thd,
+                               unsigned long long id)
+{}
diff --git a/sql/wsrep_thd.cc b/sql/wsrep_thd.cc
index 1e60088c5f1..4dddb399bd1 100644
--- a/sql/wsrep_thd.cc
+++ b/sql/wsrep_thd.cc
@@ -876,3 +876,23 @@ bool wsrep_is_load_multi_commit(THD *thd)
 {
    return thd->wsrep_split_flag;
 }
+
+void wsrep_report_bf_lock_wait(THD *thd,
+                               unsigned long long trx_id)
+{
+  if (thd)
+  {
+    WSREP_ERROR("Thread %s trx_id: %llu thread: %ld "
+                "seqno: %lld query_state: %s conf_state: %s exec_mode: %s "
+                "applier: %d query: %s",
+                wsrep_thd_is_BF(thd, false) ? "BF" : "normal",
+                trx_id,
+                thd_get_thread_id(thd),
+                wsrep_thd_trx_seqno(thd),
+                wsrep_thd_query_state_str(thd),
+                wsrep_thd_conflict_state_str(thd),
+                wsrep_thd_exec_mode_str(thd),
+                thd->wsrep_applier,
+                wsrep_thd_query(thd));
+  }
+}
diff --git a/sql/wsrep_thd.h b/sql/wsrep_thd.h
index 10efcbefbf6..46bc08a466a 100644
--- a/sql/wsrep_thd.h
+++ b/sql/wsrep_thd.h
@@ -45,6 +45,9 @@ extern "C" my_bool  wsrep_thd_is_BF_or_commit(void *thd_ptr, my_bool sync);
 extern "C" my_bool  wsrep_thd_is_local(void *thd_ptr, my_bool sync);
 extern "C" int  wsrep_thd_in_locking_session(void *thd_ptr);
 
+extern void wsrep_report_bf_lock_wait(THD *thd,
+                                      unsigned long long trx_id);
+
 #else /* WITH_WSREP */
 
 #define wsrep_thd_is_BF(T, S) (0)