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ChangeSet@stripped, 2007-08-30 23:00:33-03:00, davi@stripped +1 -0
Bug#28870 check that table locks are released/reset
The problem is that some mysql_lock_tables error paths are not resetting the
tables lock type back to TL_UNLOCK. If the lock types are not reset properly,
a table might be returned to the table cache with wrong lock_type.
The proposed fix is to ensure that the tables lock type is always properly
reset when mysql_lock_tables fails.
sql/lock.cc@stripped, 2007-08-30 23:00:29-03:00, davi@stripped +30 -24
Move mysql_lock_tables cleanup sequence to a separate function and take
steps to ensure it is always called for each error exit path.
diff -Nrup a/sql/lock.cc b/sql/lock.cc
--- a/sql/lock.cc 2007-08-27 10:13:52 -03:00
+++ b/sql/lock.cc 2007-08-30 23:00:29 -03:00
@@ -83,6 +83,22 @@ static int unlock_external(THD *thd, TAB
static void print_lock_error(int error, const char *);
/*
+ Helper function for mysql_lock_tables error path cleanup
+
+ @param thd The current thread.
+ @param sql_lock Lock structures to reset.
+*/
+static inline void mysql_lock_reset_and_free(THD *thd, MYSQL_LOCK *&sql_lock)
+{
+ if (thd->locked && sql_lock->table_count)
+ VOID(unlock_external(thd, sql_lock->table, sql_lock->table_count));
+ /* Clear the lock type of all lock data to avoid reusage. */
+ reset_lock_data(sql_lock);
+ my_free((gptr) sql_lock,MYF(0));
+ sql_lock=0;
+}
+
+/*
Lock tables.
SYNOPSIS
@@ -135,17 +151,12 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd,
*/
if (wait_if_global_read_lock(thd, 1, 1))
{
- /* Clear the lock type of all lock data to avoid reusage. */
- reset_lock_data(sql_lock);
- my_free((gptr) sql_lock,MYF(0));
- sql_lock=0;
+ mysql_lock_reset_and_free(thd, sql_lock);
break;
}
if (thd->version != refresh_version)
{
- /* Clear the lock type of all lock data to avoid reusage. */
- reset_lock_data(sql_lock);
- my_free((gptr) sql_lock,MYF(0));
+ mysql_lock_reset_and_free(thd, sql_lock);
goto retry;
}
}
@@ -154,10 +165,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd,
if (sql_lock->table_count && lock_external(thd, sql_lock->table,
sql_lock->table_count))
{
- /* Clear the lock type of all lock data to avoid reusage. */
- reset_lock_data(sql_lock);
- my_free((gptr) sql_lock,MYF(0));
- sql_lock=0;
+ mysql_lock_reset_and_free(thd, sql_lock);
break;
}
thd->proc_info="Table lock";
@@ -172,22 +180,12 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd,
thd->lock_id)];
if (rc > 1) /* a timeout or a deadlock */
{
- if (sql_lock->table_count)
- VOID(unlock_external(thd, sql_lock->table, sql_lock->table_count));
+ mysql_lock_reset_and_free(thd, sql_lock);
my_error(rc, MYF(0));
- my_free((gptr) sql_lock,MYF(0));
- sql_lock= 0;
break;
}
else if (rc == 1) /* aborted */
{
- /*
- reset_lock_data is required here. If thr_multi_lock fails it
- resets lock type for tables, which were locked before (and
- including) one that caused error. Lock type for other tables
- preserved.
- */
- reset_lock_data(sql_lock);
thd->some_tables_deleted=1; // Try again
sql_lock->lock_count= 0; // Locks are already freed
}
@@ -205,9 +203,17 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd,
}
thd->proc_info=0;
+ if (sql_lock->lock_count)
+ thr_multi_unlock(sql_lock->locks,sql_lock->lock_count);
+
+ /*
+ If thr_multi_lock fails it resets lock type for tables, which
+ were locked before (and including) one that caused error. Lock
+ type for other tables preserved.
+ */
+ mysql_lock_reset_and_free(thd, sql_lock);
+
/* some table was altered or deleted. reopen tables marked deleted */
- mysql_unlock_tables(thd,sql_lock);
- thd->locked=0;
retry:
sql_lock=0;
if (flags & MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN)
