MDEV-39344: trx_disconnect_prepared() uses wrong mutex

storage/innobase/handler/ha_innodb.cc

@@ -2953,7 +2953,7 @@ static int innobase_close_connection(handlerton *, THD *thd) noexcept
     case TRX_STATE_PREPARED:
       if (trx->has_logged_persistent())
       {
-        trx_disconnect_prepared(trx);
+        trx->disconnect_prepared();
         return 0;
       }
       /* fall through */

storage/innobase/handler/i_s.cc

@@ -187,11 +187,7 @@ static bool trx_i_s_common_fill_table(THD *thd, TABLE_LIST *tables)
   RETURN_IF_INNODB_NOT_STARTED(tables->schema_table_name.str);
 
   /* update the cache */
-  trx_i_s_cache_start_write(trx_i_s_cache);
-  trx_i_s_possibly_fetch_data_into_cache(trx_i_s_cache);
-  trx_i_s_cache_end_write(trx_i_s_cache);
-
-  if (trx_i_s_cache_is_truncated(trx_i_s_cache))
+  if (trx_i_s_possibly_fetch_data_into_cache())
     sql_print_warning("InnoDB: Data in %.*s truncated due to memory limit"
                       " of %u bytes",
                       int(tables->schema_table_name.length),
@@ -380,22 +376,20 @@ static int fill_innodb_trx_from_cache(THD *thd, TABLE_LIST *tables, Item*)
 
 	struct cache
 	{
-		cache() { trx_i_s_cache_start_read(trx_i_s_cache); }
-		~cache() { trx_i_s_cache_end_read(trx_i_s_cache); }
+		cache() { trx_i_s_cache_start_read(); }
+		~cache() { trx_i_s_cache_end_read(); }
 	} c;
 
 	Field** fields = tables->table->field;
 
-	rows_num = trx_i_s_cache_get_rows_used(trx_i_s_cache,
-					       I_S_INNODB_TRX);
+	rows_num = trx_i_s_cache_get_rows_used(I_S_INNODB_TRX);
 
 	for (i = 0; i < rows_num; i++) {
 
 		i_s_trx_row_t*	row;
 
 		row = (i_s_trx_row_t*)
-			trx_i_s_cache_get_nth_row(
-				trx_i_s_cache, I_S_INNODB_TRX, i);
+			trx_i_s_cache_get_nth_row(I_S_INNODB_TRX, i);
 
 		/* trx_id */
 		OK(fields[IDX_TRX_ID]->store(row->trx_id, true));
@@ -669,14 +663,13 @@ fill_innodb_locks_from_cache(
 
 	struct cache
 	{
-		cache() { trx_i_s_cache_start_read(trx_i_s_cache); }
-		~cache() { trx_i_s_cache_end_read(trx_i_s_cache); }
+		cache() { trx_i_s_cache_start_read(); }
+		~cache() { trx_i_s_cache_end_read(); }
 	} c;
 
 	Field** fields = tables->table->field;
 
-	rows_num = trx_i_s_cache_get_rows_used(trx_i_s_cache,
-					       I_S_INNODB_LOCKS);
+	rows_num = trx_i_s_cache_get_rows_used(I_S_INNODB_LOCKS);
 
 	for (i = 0; i < rows_num; i++) {
 
@@ -685,8 +678,7 @@ fill_innodb_locks_from_cache(
 		const char*		bufend;
 
 		row = (i_s_locks_row_t*)
-			trx_i_s_cache_get_nth_row(
-				trx_i_s_cache, I_S_INNODB_LOCKS, i);
+			trx_i_s_cache_get_nth_row(I_S_INNODB_LOCKS, i);
 
 		/* lock_id */
 		trx_i_s_create_lock_id(row, lock_id, sizeof(lock_id));
@@ -855,22 +847,20 @@ fill_innodb_lock_waits_from_cache(
 
 	struct cache
 	{
-		cache() { trx_i_s_cache_start_read(trx_i_s_cache); }
-		~cache() { trx_i_s_cache_end_read(trx_i_s_cache); }
+		cache() { trx_i_s_cache_start_read(); }
+		~cache() { trx_i_s_cache_end_read(); }
 	} c;
 
 	Field** fields = tables->table->field;
 
-	rows_num = trx_i_s_cache_get_rows_used(trx_i_s_cache,
-					       I_S_INNODB_LOCK_WAITS);
+	rows_num = trx_i_s_cache_get_rows_used(I_S_INNODB_LOCK_WAITS);
 
 	for (i = 0; i < rows_num; i++) {
 
 		i_s_lock_waits_row_t*	row;
 
 		row = (i_s_lock_waits_row_t*)
-			trx_i_s_cache_get_nth_row(
-				trx_i_s_cache, I_S_INNODB_LOCK_WAITS, i);
+			trx_i_s_cache_get_nth_row(I_S_INNODB_LOCK_WAITS, i);
 
 		/* requesting_trx_id */
 		OK(fields[IDX_REQUESTING_TRX_ID]->store(

storage/innobase/include/trx0i_s.h

@@ -146,9 +146,6 @@ struct i_s_lock_waits_row_t {
 	const i_s_locks_row_t*	blocking_lock_row;	/*!< blocking lock */
 };
 
-/** Cache of INFORMATION_SCHEMA table data */
-struct trx_i_s_cache_t;
-
 /** Auxiliary enum used by functions that need to select one of the
 INFORMATION_SCHEMA tables */
 enum i_s_table {
@@ -157,90 +154,42 @@ enum i_s_table {
 	I_S_INNODB_LOCK_WAITS	/*!< INFORMATION_SCHEMA.innodb_lock_waits */
 };
 
-/** This is the intermediate buffer where data needed to fill the
-INFORMATION SCHEMA tables is fetched and later retrieved by the C++
-code in handler/i_s.cc. */
-extern trx_i_s_cache_t*	trx_i_s_cache;
-
 /*******************************************************************//**
 Initialize INFORMATION SCHEMA trx related cache. */
-void
-trx_i_s_cache_init(
-/*===============*/
-	trx_i_s_cache_t*	cache);	/*!< out: cache to init */
+void trx_i_s_cache_init();
 /*******************************************************************//**
 Free the INFORMATION SCHEMA trx related cache. */
-void
-trx_i_s_cache_free(
-/*===============*/
-	trx_i_s_cache_t*	cache);	/*!< in/out: cache to free */
+void trx_i_s_cache_free();
 
 /*******************************************************************//**
 Issue a shared/read lock on the tables cache. */
-void
-trx_i_s_cache_start_read(
-/*=====================*/
-	trx_i_s_cache_t*	cache);	/*!< in: cache */
+void trx_i_s_cache_start_read() noexcept;
 
 /*******************************************************************//**
 Release a shared/read lock on the tables cache. */
-void
-trx_i_s_cache_end_read(
-/*===================*/
-	trx_i_s_cache_t*	cache);	/*!< in: cache */
-
-/*******************************************************************//**
-Issue an exclusive/write lock on the tables cache. */
-void
-trx_i_s_cache_start_write(
-/*======================*/
-	trx_i_s_cache_t*	cache);	/*!< in: cache */
-
-/*******************************************************************//**
-Release an exclusive/write lock on the tables cache. */
-void
-trx_i_s_cache_end_write(
-/*====================*/
-	trx_i_s_cache_t*	cache);	/*!< in: cache */
-
+void trx_i_s_cache_end_read() noexcept;
 
 /*******************************************************************//**
 Retrieves the number of used rows in the cache for a given
 INFORMATION SCHEMA table.
+@param table  table to be read
 @return number of rows */
-ulint
-trx_i_s_cache_get_rows_used(
-/*========================*/
-	trx_i_s_cache_t*	cache,	/*!< in: cache */
-	enum i_s_table		table);	/*!< in: which table */
+ulint trx_i_s_cache_get_rows_used(i_s_table table);
 
 /*******************************************************************//**
 Retrieves the nth row in the cache for a given INFORMATION SCHEMA
 table.
+@param table table to read
+@param n     row number
 @return row */
-void*
-trx_i_s_cache_get_nth_row(
-/*======================*/
-	trx_i_s_cache_t*	cache,	/*!< in: cache */
-	enum i_s_table		table,	/*!< in: which table */
-	ulint			n);	/*!< in: row number */
+void *trx_i_s_cache_get_nth_row(i_s_table table, ulint n);
 
 /*******************************************************************//**
 Update the transactions cache if it has not been read for some time.
-@return 0 - fetched, 1 - not */
-int
-trx_i_s_possibly_fetch_data_into_cache(
-/*===================================*/
-	trx_i_s_cache_t*	cache);	/*!< in/out: cache */
+@retval false when fetched or cached
+@retval true if fetched but the cache was truncated */
+bool trx_i_s_possibly_fetch_data_into_cache();
 
-/*******************************************************************//**
-Returns true, if the data in the cache is truncated due to the memory
-limit posed by TRX_I_S_MEM_LIMIT.
-@return TRUE if truncated */
-bool
-trx_i_s_cache_is_truncated(
-/*=======================*/
-	trx_i_s_cache_t*	cache);	/*!< in: cache */
 /** The maximum length of a resulting lock_id_size in
 trx_i_s_create_lock_id(), not including the terminating NUL.
 ":%lu:%lu:%lu" -> 63 chars */

storage/innobase/include/trx0sys.h

@@ -825,9 +825,6 @@ class thread_safe_trx_ilist_t
     mysql_mutex_unlock(&mutex);
   }
 
-  void freeze() const { mysql_mutex_lock(&mutex); }
-  void unfreeze() const { mysql_mutex_unlock(&mutex); }
-
 private:
   alignas(CPU_LEVEL1_DCACHE_LINESIZE) mutable mysql_mutex_t mutex;
   alignas(CPU_LEVEL1_DCACHE_LINESIZE) ilist<trx_t> trx_list;

storage/innobase/include/trx0trx.h

@@ -73,10 +73,6 @@ trx_t *trx_create();
 /** At shutdown, frees a transaction object. */
 void trx_free_at_shutdown(trx_t *trx);
 
-/** Disconnect a prepared transaction from MySQL.
-@param[in,out]	trx	transaction */
-void trx_disconnect_prepared(trx_t *trx);
-
 /** Initialize (resurrect) transactions at startup. */
 dberr_t trx_lists_init_at_db_start();
 
@@ -730,7 +726,7 @@ struct trx_t : ilist_node<>
 	This field is accessed by the thread that owns the transaction,
 	without holding any mutex.
 	There is only one foreign-thread access in trx_print_low()
-	and a possible race condition with trx_disconnect_prepared(). */
+	and a possible race condition with disconnect_prepared(). */
 	bool		is_recovered;
 	const char*	op_info;	/*!< English text describing the
 					current operation, or an empty
@@ -968,6 +964,8 @@ struct trx_t : ilist_node<>
 public:
   /** Commit the transaction. */
   void commit() noexcept;
+  /** Disconnect a prepared transaction */
+  void disconnect_prepared() noexcept;
 
   /** Try to drop a persistent table.
   @param table       persistent table

storage/innobase/srv/srv0srv.cc

@@ -621,7 +621,7 @@ static void srv_init()
 			 &page_zip_stat_per_index_mutex, nullptr);
 
 	/* Initialize some INFORMATION SCHEMA internal structures */
-	trx_i_s_cache_init(trx_i_s_cache);
+	trx_i_s_cache_init();
 }
 
 /*********************************************************************//**
@@ -638,7 +638,7 @@ srv_free(void)
 	mysql_mutex_destroy(&page_zip_stat_per_index_mutex);
 	mysql_mutex_destroy(&srv_sys.tasks_mutex);
 
-	trx_i_s_cache_free(trx_i_s_cache);
+	trx_i_s_cache_free();
 	srv_thread_pool_end();
 }