diff --git a/mysql-test/r/lock_multi.result b/mysql-test/r/lock_multi.result
index 180c8f41b70d2f6e998a64f45396718a18422fbe..6d31d01d154b257fb7a349698b15114dae3c650b 100644
--- a/mysql-test/r/lock_multi.result
+++ b/mysql-test/r/lock_multi.result
@@ -50,6 +50,14 @@ Field Type Null Key Default Extra
a int(11) YES NULL
unlock tables;
drop table t1;
+CREATE DATABASE mysqltest_1;
+FLUSH TABLES WITH READ LOCK;
+ DROP DATABASE mysqltest_1;
+DROP DATABASE mysqltest_1;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+UNLOCK TABLES;
+DROP DATABASE mysqltest_1;
+ERROR HY000: Can't drop database 'mysqltest_1'; database doesn't exist
use mysql;
LOCK TABLES columns_priv WRITE, db WRITE, host WRITE, user WRITE;
FLUSH TABLES;
diff --git a/mysql-test/t/lock_multi.test b/mysql-test/t/lock_multi.test
index a24ee8be64ef29a288865ad160ceba9da9f20457..7fc65f52214d6cb2f5bef6cffda121f13aab3f5c 100644
--- a/mysql-test/t/lock_multi.test
+++ b/mysql-test/t/lock_multi.test
@@ -128,6 +128,39 @@ unlock tables;
drop table t1;
#
+# Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock
+#
+connect (con1,localhost,root,,);
+connect (con2,localhost,root,,);
+#
+connection con1;
+CREATE DATABASE mysqltest_1;
+FLUSH TABLES WITH READ LOCK;
+#
+# With bug in place: acquire LOCK_mysql_create_table and
+# wait in wait_if_global_read_lock().
+connection con2;
+send DROP DATABASE mysqltest_1;
+--sleep 1
+#
+# With bug in place: try to acquire LOCK_mysql_create_table...
+# When fixed: Reject dropping db because of the read lock.
+connection con1;
+--error ER_CANT_UPDATE_WITH_READLOCK
+DROP DATABASE mysqltest_1;
+UNLOCK TABLES;
+#
+connection con2;
+reap;
+#
+connection default;
+disconnect con1;
+disconnect con2;
+# This must have been dropped by connection 2 already,
+# which waited until the global read lock was released.
+--error ER_DB_DROP_EXISTS
+DROP DATABASE mysqltest_1;
+
# Bug#16986 - Deadlock condition with MyISAM tables
#
connection locker;
diff --git a/sql/sql_db.cc b/sql/sql_db.cc
index 6d5362c2554a29d9f585313245452ae8ea2037bf..11c892fee44c0b757e614ece8d287d4ea9158bc5 100644
--- a/sql/sql_db.cc
+++ b/sql/sql_db.cc
@@ -538,16 +538,27 @@ bool mysql_create_db(THD *thd, char *db, HA_CREATE_INFO *create_info,
my_error(ER_DB_CREATE_EXISTS, MYF(0), db);
DBUG_RETURN(-1);
}
-
- VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
- /* do not create database if another thread is holding read lock */
+ /*
+ Do not create database if another thread is holding read lock.
+ Wait for global read lock before acquiring LOCK_mysql_create_db.
+ After wait_if_global_read_lock() we have protection against another
+ global read lock. If we would acquire LOCK_mysql_create_db first,
+ another thread could step in and get the global read lock before we
+ reach wait_if_global_read_lock(). If this thread tries the same as we
+ (admin a db), it would then go and wait on LOCK_mysql_create_db...
+ Furthermore wait_if_global_read_lock() checks if the current thread
+ has the global read lock and refuses the operation with
+ ER_CANT_UPDATE_WITH_READLOCK if applicable.
+ */
if (wait_if_global_read_lock(thd, 0, 1))
{
error= -1;
goto exit2;
}
+ VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
+
/* Check directory */
path_len= build_table_filename(path, sizeof(path), db, "", "");
path[path_len-1]= 0; // Remove last '/' from path
@@ -655,9 +666,9 @@ bool mysql_create_db(THD *thd, char *db, HA_CREATE_INFO *create_info,
}
exit:
+ VOID(pthread_mutex_unlock(&LOCK_mysql_create_db));
start_waiting_global_read_lock(thd);
exit2:
- VOID(pthread_mutex_unlock(&LOCK_mysql_create_db));
DBUG_RETURN(error);
}
@@ -671,12 +682,23 @@ bool mysql_alter_db(THD *thd, const char *db, HA_CREATE_INFO *create_info)
int error= 0;
DBUG_ENTER("mysql_alter_db");
- VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
-
- /* do not alter database if another thread is holding read lock */
+ /*
+ Do not alter database if another thread is holding read lock.
+ Wait for global read lock before acquiring LOCK_mysql_create_db.
+ After wait_if_global_read_lock() we have protection against another
+ global read lock. If we would acquire LOCK_mysql_create_db first,
+ another thread could step in and get the global read lock before we
+ reach wait_if_global_read_lock(). If this thread tries the same as we
+ (admin a db), it would then go and wait on LOCK_mysql_create_db...
+ Furthermore wait_if_global_read_lock() checks if the current thread
+ has the global read lock and refuses the operation with
+ ER_CANT_UPDATE_WITH_READLOCK if applicable.
+ */
if ((error=wait_if_global_read_lock(thd,0,1)))
goto exit2;
+ VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
+
/*
Recreate db options file: /dbpath/.db.opt
We pass MY_DB_OPT_FILE as "extension" to avoid
@@ -721,9 +743,9 @@ bool mysql_alter_db(THD *thd, const char *db, HA_CREATE_INFO *create_info)
send_ok(thd, result);
exit:
+ VOID(pthread_mutex_unlock(&LOCK_mysql_create_db));
start_waiting_global_read_lock(thd);
exit2:
- VOID(pthread_mutex_unlock(&LOCK_mysql_create_db));
DBUG_RETURN(error);
}
@@ -755,15 +777,26 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
TABLE_LIST* dropped_tables= 0;
DBUG_ENTER("mysql_rm_db");
- VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
-
- /* do not drop database if another thread is holding read lock */
+ /*
+ Do not drop database if another thread is holding read lock.
+ Wait for global read lock before acquiring LOCK_mysql_create_db.
+ After wait_if_global_read_lock() we have protection against another
+ global read lock. If we would acquire LOCK_mysql_create_db first,
+ another thread could step in and get the global read lock before we
+ reach wait_if_global_read_lock(). If this thread tries the same as we
+ (admin a db), it would then go and wait on LOCK_mysql_create_db...
+ Furthermore wait_if_global_read_lock() checks if the current thread
+ has the global read lock and refuses the operation with
+ ER_CANT_UPDATE_WITH_READLOCK if applicable.
+ */
if (wait_if_global_read_lock(thd, 0, 1))
{
error= -1;
goto exit2;
}
+ VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
+
length= build_table_filename(path, sizeof(path), db, "", "");
strmov(path+length, MY_DB_OPT_FILE); // Append db option file name
del_dbopt(path); // Remove dboption hash entry
@@ -872,7 +905,6 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
exit:
(void)sp_drop_db_routines(thd, db); /* QQ Ignore errors for now */
error= Events::drop_schema_events(thd, db);
- start_waiting_global_read_lock(thd);
/*
If this database was the client's selected database, we silently change the
client's selected database to nothing (to have an empty SELECT DATABASE()
@@ -901,9 +933,9 @@ exit:
thd->db= 0;
thd->db_length= 0;
}
-exit2:
VOID(pthread_mutex_unlock(&LOCK_mysql_create_db));
-
+ start_waiting_global_read_lock(thd);
+exit2:
DBUG_RETURN(error);
}
diff --git a/storage/myisam/mi_check.c b/storage/myisam/mi_check.c
index ef7b1e6fde39d1a5492473ddefbd18cc0350199e..d91597e9138606b130afe55d1132eb52c7bff7ad 100644
--- a/storage/myisam/mi_check.c
+++ b/storage/myisam/mi_check.c
@@ -453,25 +453,24 @@ int chk_key(MI_CHECK *param, register MI_INFO *info)
if ((uint) share->base.auto_key -1 == key)
{
/* Check that auto_increment key is bigger than max key value */
- ulonglong save_auto_value=info->s->state.auto_increment;
- info->s->state.auto_increment=0;
+ ulonglong auto_increment;
info->lastinx=key;
_mi_read_key_record(info, 0L, info->rec_buff);
- update_auto_increment(info, info->rec_buff);
- if (info->s->state.auto_increment > save_auto_value)
+ auto_increment= retrieve_auto_increment(info, info->rec_buff);
+ if (auto_increment > info->s->state.auto_increment)
{
- mi_check_print_warning(param,
- "Auto-increment value: %s is smaller than max used value: %s",
- llstr(save_auto_value,buff2),
- llstr(info->s->state.auto_increment, buff));
+ mi_check_print_warning(param, "Auto-increment value: %s is smaller "
+ "than max used value: %s",
+ llstr(info->s->state.auto_increment,buff2),
+ llstr(auto_increment, buff));
}
if (param->testflag & T_AUTO_INC)
{
- set_if_bigger(info->s->state.auto_increment,
- param->auto_increment_value);
+ set_if_bigger(info->s->state.auto_increment,
+ auto_increment);
+ set_if_bigger(info->s->state.auto_increment,
+ param->auto_increment_value);
}
- else
- info->s->state.auto_increment=save_auto_value;
/* Check that there isn't a row with auto_increment = 0 in the table */
mi_extra(info,HA_EXTRA_KEYREAD,0);
@@ -481,8 +480,8 @@ int chk_key(MI_CHECK *param, register MI_INFO *info)
{
/* Don't count this as a real warning, as myisamchk can't correct it */
uint save=param->warning_printed;
- mi_check_print_warning(param,
- "Found row where the auto_increment column has the value 0");
+ mi_check_print_warning(param, "Found row where the auto_increment "
+ "column has the value 0");
param->warning_printed=save;
}
mi_extra(info,HA_EXTRA_NO_KEYREAD,0);
@@ -4124,11 +4123,10 @@ void update_auto_increment_key(MI_CHECK *param, MI_INFO *info,
}
else
{
- ulonglong auto_increment= (repair_only ? info->s->state.auto_increment :
- param->auto_increment_value);
- info->s->state.auto_increment=0;
- update_auto_increment(info, record);
+ ulonglong auto_increment= retrieve_auto_increment(info, record);
set_if_bigger(info->s->state.auto_increment,auto_increment);
+ if (!repair_only)
+ set_if_bigger(info->s->state.auto_increment, param->auto_increment_value);
}
mi_extra(info,HA_EXTRA_NO_KEYREAD,0);
my_free((char*) record, MYF(0));
diff --git a/storage/myisam/mi_key.c b/storage/myisam/mi_key.c
index 526a733e724601dace0cd9f29d230c2e07a2ffeb..01bd0c431196652347cee828f235941619050fb7 100644
--- a/storage/myisam/mi_key.c
+++ b/storage/myisam/mi_key.c
@@ -507,22 +507,21 @@ int _mi_read_key_record(MI_INFO *info, my_off_t filepos, byte *buf)
return(-1); /* Wrong data to read */
}
-
+
/*
- Update auto_increment info
+ Retrieve auto_increment info
SYNOPSIS
- update_auto_increment()
+ retrieve_auto_increment()
info MyISAM handler
record Row to update
IMPLEMENTATION
- Only replace the auto_increment value if it is higher than the previous
- one. For signed columns we don't update the auto increment value if it's
+ For signed columns we don't retrieve the auto increment value if it's
less than zero.
*/
-void update_auto_increment(MI_INFO *info,const byte *record)
+ulonglong retrieve_auto_increment(MI_INFO *info,const byte *record)
{
ulonglong value= 0; /* Store unsigned values here */
longlong s_value= 0; /* Store signed values here */
@@ -587,6 +586,5 @@ void update_auto_increment(MI_INFO *info,const byte *record)
and if s_value == 0 then value will contain either s_value or the
correct value.
*/
- set_if_bigger(info->s->state.auto_increment,
- (s_value > 0) ? (ulonglong) s_value : value);
+ return (s_value > 0) ? (ulonglong) s_value : value;
}
diff --git a/storage/myisam/mi_update.c b/storage/myisam/mi_update.c
index 937c9983b452586a4c18a2618d3a24ea53b47397..f8b5cf55406819e2a94c07254ae0b53b9e233e0c 100644
--- a/storage/myisam/mi_update.c
+++ b/storage/myisam/mi_update.c
@@ -164,7 +164,8 @@ int mi_update(register MI_INFO *info, const byte *oldrec, byte *newrec)
key_changed|= HA_STATE_CHANGED; /* Must update index file */
}
if (auto_key_changed)
- update_auto_increment(info,newrec);
+ set_if_bigger(info->s->state.auto_increment,
+ retrieve_auto_increment(info, newrec));
if (share->calc_checksum)
info->state->checksum+=(info->checksum - old_checksum);
diff --git a/storage/myisam/mi_write.c b/storage/myisam/mi_write.c
index 5e79b2937cc5f0e7841efb4a4db3c7c459c636c2..9ab8753f6d714d4216629e5ce48e2962e371d9f7 100644
--- a/storage/myisam/mi_write.c
+++ b/storage/myisam/mi_write.c
@@ -149,7 +149,8 @@ int mi_write(MI_INFO *info, byte *record)
info->state->checksum+=info->checksum;
}
if (share->base.auto_key)
- update_auto_increment(info,record);
+ set_if_bigger(info->s->state.auto_increment,
+ retrieve_auto_increment(info, record));
info->update= (HA_STATE_CHANGED | HA_STATE_AKTIV | HA_STATE_WRITTEN |
HA_STATE_ROW_CHANGED);
info->state->records++;
diff --git a/storage/myisam/myisamdef.h b/storage/myisam/myisamdef.h
index a83fbe8f759d29194fe40b1b63265cf02c297e6b..baab34b4b676fe4dae5c11f762498b3a7cf6be7c 100644
--- a/storage/myisam/myisamdef.h
+++ b/storage/myisam/myisamdef.h
@@ -593,7 +593,7 @@ extern uint _mi_pack_key(MI_INFO *info,uint keynr,uchar *key,uchar *old,
extern int _mi_read_key_record(MI_INFO *info,my_off_t filepos,byte *buf);
extern int _mi_read_cache(IO_CACHE *info,byte *buff,my_off_t pos,
uint length,int re_read_if_possibly);
-extern void update_auto_increment(MI_INFO *info,const byte *record);
+extern ulonglong retrieve_auto_increment(MI_INFO *info,const byte *record);
extern byte *mi_alloc_rec_buff(MI_INFO *,ulong, byte**);
#define mi_get_rec_buff_ptr(info,buf) \