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perfschema: LOCK_all_status_vars not LOCK_status

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to iterate over all status variables one should use
LOCK_all_status_vars not LOCK_status

this fixes sporadic mutex lock inversion in plugins.password_reuse_check:
* acl_cache->lock is taken over complex operations that might increment
  status counters (under LOCK_status).
* acl_cache->lock is needed to get the values of Acl% status variables
  when iterating over status variables
This commit is contained in:
Sergei Golubchik
2023-12-18 17:37:30 +01:00
parent fd0b47f9d6
commit 07a0173f1c
2 changed files with 26 additions and 41 deletions
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64
storage/perfschema/pfs_variable.cc
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@@ -762,7 +762,7 @@ bool PFS_status_variable_cache::filter_show_var(const SHOW_VAR *show_var, bool s
/**
Build an array of SHOW_VARs from the global status array. Expand nested
subarrays, filter unwanted variables.
NOTE: Must be done inside of LOCK_status to guard against plugin load/unload.
NOTE: Must be done under LOCK_all_status_vars
*/
bool PFS_status_variable_cache::init_show_var_array(enum_var_type scope, bool strict)
{
@@ -881,14 +881,12 @@ char * PFS_status_variable_cache::make_show_var_name(const char* prefix, const c
*/
bool PFS_status_variable_cache::do_initialize_session(void)
{
/* Acquire LOCK_status to guard against plugin load/unload. */
//if (m_current_thd->fill_status_recursion_level++ == 0)
mysql_mutex_lock(&LOCK_status);
/* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
mysql_rwlock_rdlock(&LOCK_all_status_vars);
bool ret= init_show_var_array(OPT_SESSION, true);
//if (m_current_thd->fill_status_recursion_level-- == 1)
mysql_mutex_unlock(&LOCK_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
return ret;
}
@@ -917,13 +915,12 @@ int PFS_status_variable_cache::do_materialize_global(void)
m_materialized= false;
DEBUG_SYNC(m_current_thd, "before_materialize_global_status_array");
/* Acquire LOCK_status to guard against plugin load/unload. */
//if (m_current_thd->fill_status_recursion_level++ == 0)
mysql_mutex_lock(&LOCK_status);
/* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
mysql_rwlock_rdlock(&LOCK_all_status_vars);
/*
Build array of SHOW_VARs from global status array. Do this within
LOCK_status to ensure that the array remains unchanged during
Build array of SHOW_VARs from global status array. Do this under
LOCK_all_status_vars to ensure that the array remains unchanged during
materialization.
*/
if (!m_external_init)
@@ -946,8 +943,7 @@ int PFS_status_variable_cache::do_materialize_global(void)
*/
manifest(m_current_thd, m_show_var_array.front(), &status_totals, "", false, true);
//if (m_current_thd->fill_status_recursion_level-- == 1)
mysql_mutex_unlock(&LOCK_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
m_materialized= true;
DEBUG_SYNC(m_current_thd, "after_materialize_global_status_array");
@@ -967,13 +963,11 @@ int PFS_status_variable_cache::do_materialize_all(THD* unsafe_thd)
m_materialized= false;
m_cache.clear();
/* Avoid recursive acquisition of LOCK_status. */
//if (m_current_thd->fill_status_recursion_level++ == 0)
mysql_mutex_lock(&LOCK_status);
mysql_rwlock_rdlock(&LOCK_all_status_vars);
/*
Build array of SHOW_VARs from global status array. Do this within
LOCK_status to ensure that the array remains unchanged while this
Build array of SHOW_VARs from global status array. Do this under
LOCK_all_status_vars to ensure that the array remains unchanged while this
thread is materialized.
*/
if (!m_external_init)
@@ -996,8 +990,7 @@ int PFS_status_variable_cache::do_materialize_all(THD* unsafe_thd)
ret= 0;
}
//if (m_current_thd->fill_status_recursion_level-- == 1)
mysql_mutex_unlock(&LOCK_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
return ret;
}
@@ -1013,13 +1006,11 @@ int PFS_status_variable_cache::do_materialize_session(THD* unsafe_thd)
m_materialized= false;
m_cache.clear();
/* Avoid recursive acquisition of LOCK_status. */
//if (m_current_thd->fill_status_recursion_level++ == 0)
mysql_mutex_lock(&LOCK_status);
mysql_rwlock_rdlock(&LOCK_all_status_vars);
/*
Build array of SHOW_VARs from global status array. Do this within
LOCK_status to ensure that the array remains unchanged while this
Build array of SHOW_VARs from global status array. Do this under
LOCK_all_status_vars to ensure that the array remains unchanged while this
thread is materialized.
*/
if (!m_external_init)
@@ -1042,8 +1033,7 @@ int PFS_status_variable_cache::do_materialize_session(THD* unsafe_thd)
ret= 0;
}
//if (m_current_thd->fill_status_recursion_level-- == 1)
mysql_mutex_unlock(&LOCK_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
return ret;
}
@@ -1060,9 +1050,8 @@ int PFS_status_variable_cache::do_materialize_session(PFS_thread *pfs_thread)
m_materialized= false;
m_cache.clear();
/* Acquire LOCK_status to guard against plugin load/unload. */
//if (m_current_thd->fill_status_recursion_level++ == 0)
mysql_mutex_lock(&LOCK_status);
/* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
mysql_rwlock_rdlock(&LOCK_all_status_vars);
/* The SHOW_VAR array must be initialized externally. */
assert(m_initialized);
@@ -1084,8 +1073,7 @@ int PFS_status_variable_cache::do_materialize_session(PFS_thread *pfs_thread)
ret= 0;
}
//if (m_current_thd->fill_status_recursion_level-- == 1)
mysql_mutex_unlock(&LOCK_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
return ret;
}
@@ -1104,9 +1092,8 @@ int PFS_status_variable_cache::do_materialize_client(PFS_client *pfs_client)
m_materialized= false;
m_cache.clear();
/* Acquire LOCK_status to guard against plugin load/unload. */
//if (m_current_thd->fill_status_recursion_level++ == 0)
mysql_mutex_lock(&LOCK_status);
/* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
mysql_rwlock_rdlock(&LOCK_all_status_vars);
/* The SHOW_VAR array must be initialized externally. */
assert(m_initialized);
@@ -1123,8 +1110,7 @@ int PFS_status_variable_cache::do_materialize_client(PFS_client *pfs_client)
*/
manifest(m_current_thd, m_show_var_array.front(), &status_totals, "", false, true);
//if (m_current_thd->fill_status_recursion_level-- == 1)
mysql_mutex_unlock(&LOCK_status);
mysql_rwlock_unlock(&LOCK_all_status_vars);
m_materialized= true;
return 0;
@@ -1217,7 +1203,7 @@ Status_variable::Status_variable(const SHOW_VAR *show_var, STATUS_VAR *status_va
/**
Resolve status value, convert to string.
show_var->value is an offset into status_vars.
NOTE: Assumes LOCK_status is held.
NOTE: Assumes LOCK_all_status_vars is held.
*/
void Status_variable::init(const SHOW_VAR *show_var, STATUS_VAR *status_vars, enum_var_type query_scope)
{
@@ -1283,7 +1269,7 @@ void sum_account_status(PFS_client *pfs_account, STATUS_VAR *status_totals)
/**
Reset aggregated status counter stats for account, user and host.
NOTE: Assumes LOCK_status is held.
NOTE: Assumes LOCK_all_status_vars is held.
*/
void reset_pfs_status_stats()
{