Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
client/mysqldump.c:
Pass my_free directly as its signature is compatible with the
callback type -- which wasn't the case for free_table_ent.
Prior to this fix, mysys mutexes such as THR_LOCK_lock could be initialized
twice by a call to my_init().
The root cause was out of place initialization in my_basic_init(),
calling my_thread_global_init().
With this fix,
- my_basic_init() properly initializes the mutex implementation itself,
for SAFE or FAST mutexes, and for platform dependent initializations,
before initialiazing a mutex.
- my_init() properly initializes mysys mutexes once,
when making the first call to my_thread_global_init().
In order to allow thread schedulers to be dynamically loaded,
it is necessary to make the following changes to the server:
- Two new service interfaces
- Modifications to InnoDB to inform the thread scheduler of state changes.
- Changes to the VIO subsystem for checking if data is available on a socket.
- Elimination of remains of the old thread pool implementation.
The two new service interfaces introduces are:
my_thread_scheduler
A service interface to register a thread
scheduler.
thd_wait
A service interface to inform thread scheduler
that the thread is about to start waiting.
In addition, the patch adds code that:
- Add a call to thd_wait for table locks in mysys
thd_lock.c by introducing a set function that
can be used to set a callback to be used when
waiting on a lock and resuming from waiting.
- Calling the mysys set function from the server
to set the callbacks correctly.
Conflicts:
Text conflict in client/mysqlbinlog.cc
Text conflict in mysql-test/Makefile.am
Text conflict in mysql-test/collections/default.daily
Text conflict in mysql-test/r/mysqlbinlog_row_innodb.result
Text conflict in mysql-test/suite/rpl/r/rpl_typeconv_innodb.result
Text conflict in mysql-test/suite/rpl/t/rpl_get_master_version_and_clock.test
Text conflict in mysql-test/suite/rpl/t/rpl_row_create_table.test
Text conflict in mysql-test/suite/rpl/t/rpl_slave_skip.test
Text conflict in mysql-test/suite/rpl/t/rpl_typeconv_innodb.test
Text conflict in mysys/charset.c
Text conflict in sql/field.cc
Text conflict in sql/field.h
Text conflict in sql/item.h
Text conflict in sql/item_func.cc
Text conflict in sql/log.cc
Text conflict in sql/log_event.cc
Text conflict in sql/log_event_old.cc
Text conflict in sql/mysqld.cc
Text conflict in sql/rpl_utility.cc
Text conflict in sql/rpl_utility.h
Text conflict in sql/set_var.cc
Text conflict in sql/share/Makefile.am
Text conflict in sql/sql_delete.cc
Text conflict in sql/sql_plugin.cc
Text conflict in sql/sql_select.cc
Text conflict in sql/sql_table.cc
Text conflict in storage/example/ha_example.h
Text conflict in storage/federated/ha_federated.cc
Text conflict in storage/myisammrg/ha_myisammrg.cc
Text conflict in storage/myisammrg/myrg_open.c
Conflicts:
Text conflict in .bzr-mysql/default.conf
Text conflict in mysql-test/r/explain.result
Text conflict in mysql-test/r/having.result
Text conflict in mysql-test/suite/rpl/t/disabled.def
Text conflict in mysql-test/suite/rpl/t/rpl_slave_skip.test
Text conflict in storage/federated/ha_federated.cc
A client doing multiple mysql_library_init() and
mysql_library_end() calls over the lifetime of the process may
experience lost character set data, potentially even a
SIGSEGV.
This patch reinstates the reloading of character set data when
a mysql_library_init() is done after a mysql_library_end().
Before this fix, opening a configuration file located under "~" failed.
To evaluate the "~" path, home_dir needs to be initialized.
The 'home_dir' variable was initialized too late in my_init().
This fix:
- moved the home_dir initialization from my_init() to my_basic_init(),
using getenv("HOME"))
- moved the initialization of my_umask / my_umask_dir also to
my_basic_init(), to have all the my_umask / my_umask_dir init code in the
same place.
The second part is not strictly required, but makes the code more
maintainable.
Tested the fix manually.
No MTR tests added, because MTR should not access or modify the $HOME
directory of the user running tests.
As documented in the bug report, the double checked locking
pattern has inherent issues, and cannot guarantee correct
initialization.
This patch replaces the logic in init_available_charsets()
with the use of pthread_once(3). A wrapper function,
my_pthread_once(), is introduced and is used in lieu of direct
calls to init_available_charsets(). Related defines
MY_PTHREAD_ONCE_* are also introduced.
For the Windows platform, the implementation in lp:sysbench is
ported. For single-thread use, a simple define calls the
function and sets the pthread_once control variable.
Charset initialization is modified to use my_pthread_once().
include/my_no_pthread.h:
Dummy my_pthread_once() for single thread use.
include/my_pthread.h:
Declaration for new function my_pthread_once().
mysys/charset.c:
Logic in init_available_charsets() is simplified.
Using my_pthread_once() for all calls to this func.
mysys/my_winthread.c:
Windows implementation of my_pthread_once().
http://lists.mysql.com/commits/57725
Vladislav Vaintroub 2008-11-03
Cleanup CMakeLists.txt(s) - remove winsock2 (ws2_32) from
TARGET_LINK_LIBRARIES.
Every exe or dll linked with mysys needs ws2_32, because
mysys uses winsock function WSAStartup in my_init().
However, there is no need to explicitely add ws2_32 to
the list of TARGET_LINK_LIBRARIES multiple times.
Visual Studio comes with a handy pragma that tells linker
to add library. So patch replaces bunch of ws2_32 in
CMakeLists with single pragma comment(lib,"ws2_32")
in my_init.c
Additionally, reference to non-existing "debug" library
has been removed from TARGET_LINK_LIBRARIES. The correct
name of the library is "dbug".
* Finished Monty and Jani's merge
* Some InnoDB tests still fail (because it's old xtradb code run against
newer testsuite). They are expected to go after mergning with the latest
xtradb.
mysql-test/r/information_schema.result:
Fixed a result file.
mysql-test/r/innodb-autoinc.result:
Fixed a result file.
mysql-test/t/connect.test:
Fixed a problem with merge, needed to close
connections and use the default
Bug#44091: libmysqld gets stuck waiting on mutex on initialization
The problem was that libmysqld wasn't enforcing a certain
initialization and deinitialization order for the mysys
library. Another problem was that the global object used
for management of log event handlers (aka LOGGER) wasn't
being prepared for a possible reutilization.
What leads to the hang/crash reported is that a failure
to load the language file triggers a double call of the
cleanup functions, causing an already destroyed mutex to
be used.
The solution is enforce a order on the initialization and
deinitialization of the mysys library within the libmysqld
library and to ensure that the global LOGGER object reset
it's internal state during cleanup.
mysys/my_init.c:
Deinitialize only if initialized already.
sql/log.cc:
Reset state.
- adding back Serg's "mtr --list-options"
- safe_mutex deadlock detector started raising wrong deadlock warnings, fixed
here by a backport from 6.0-main.
include/my_pthread.h:
Porting changes done to 6.0-main which satisfy the safe_mutex deadlock detector (those
in 5.1-main don't), see chad@mysql.com-20090126155607-n0j3zbmgbfepnmmo for explanations
mysql-test/mysql-test-run.pl:
adding back Serg's --list-options
mysys/my_init.c:
Porting changes done to 6.0-main which satisfy the safe_mutex deadlock detector (those
in 5.1-main don't), see chad@mysql.com-20090126155607-n0j3zbmgbfepnmmo for explanations
mysys/my_thr_init.c:
Porting changes done to 6.0-main which satisfy the safe_mutex deadlock detector (those
in 5.1-main don't), see chad@mysql.com-20090126155607-n0j3zbmgbfepnmmo for explanations
There were so many changes into mtr (this is the new mtr coming) that I rather
copied mtr from 6.0-main here (at least this one knows how to run Maria tests).
I also fixed suite/maria tests to be accepted by the new mtr.
mysys/thr_mutex.c:
adding DBUG_PRINT here, so that we can locate where the warning is issued.
code backported from 6.0
per-file messages:
include/my_global.h
Remove SC_MAXWIDTH. This is unused and irrelevant nowadays.
include/my_sys.h
Remove errbuf declaration and unused definitions.
mysys/my_error.c
Remove errbuf definition and move and adjust ERRMSGSIZE.
mysys/my_init.c
Declare buffer on the stack and use my_snprintf.
mysys/safemalloc.c
Use size explicitly. It's more than enough for the message at hand.
sql/sql_error.cc
Use size explicitly. It's more than enough for the message at hand.
sql/sql_parse.cc
Declare buffer on the stack. Use my_snprintf as it will result in
less stack space being used than by a system provided sprintf --
this allows us to put the buffer on the stack without causing much
trouble. Also, the use of errbuff here was not thread-safe as the
function can be entered concurrently from multiple threads.
sql/sql_table.cc
Use MYSQL_ERRMSG_SIZE. Extra space is not needed as my_snprintf will
nul terminate strings.
storage/myisam/ha_myisam.cc
Use MYSQL_ERRMSG_SIZE.
sql/share/errmsg.txt
Error message truncation in test "innodb" in embedded mode
filename in the error message can safely take up to 210 symbols.
conflicts:
Text conflict in client/mysqltest.cc
Text conflict in mysql-test/include/wait_until_connected_again.inc
Text conflict in mysql-test/lib/mtr_report.pm
Text conflict in mysql-test/mysql-test-run.pl
Text conflict in mysql-test/r/events_bugs.result
Text conflict in mysql-test/r/log_state.result
Text conflict in mysql-test/r/myisam_data_pointer_size_func.result
Text conflict in mysql-test/r/mysqlcheck.result
Text conflict in mysql-test/r/query_cache.result
Text conflict in mysql-test/r/status.result
Text conflict in mysql-test/suite/binlog/r/binlog_index.result
Text conflict in mysql-test/suite/binlog/r/binlog_innodb.result
Text conflict in mysql-test/suite/rpl/r/rpl_packet.result
Text conflict in mysql-test/suite/rpl/t/rpl_packet.test
Text conflict in mysql-test/t/disabled.def
Text conflict in mysql-test/t/events_bugs.test
Text conflict in mysql-test/t/log_state.test
Text conflict in mysql-test/t/myisam_data_pointer_size_func.test
Text conflict in mysql-test/t/mysqlcheck.test
Text conflict in mysql-test/t/query_cache.test
Text conflict in mysql-test/t/rpl_init_slave_func.test
Text conflict in mysql-test/t/status.test
Bug#36428: MY_MUTEX_INIT_FAST is used before initialization
On some thread implementations, we need a fake mutex attri-
bute as a placeholder, which we define as a global variable,
"my_fast_mutexattr". Well. that must be initialized before
used in any mutexes, and the ordering of initializations in
the API function my_init() was wrong.
Now, put my_thread_global_init(), which initializes the attri-
butes that mutexes require.
This writes a warning on stderr if one uses mutex in different order,
like if one in one case would lock mutex in the order A,B and in another case
would lock mutex in the order B,A
This is inspired by and loosely based on the LOCKDEP patch by Jonas
Wrong mutex order is either fixed or mutex are marked with MYF_NO_DEADLOCK_DETECTION
if used inconsistently (need to be fixed by server team)
KNOWN_BUGS.txt:
Added information that one need to dump and restore Maria tables
include/hash.h:
Added prototype function for walking over all elements in a hash
include/my_pthread.h:
Added my_pthread_mutex_init() and my_pthread_mutex_lock(); These should be used if one wants to disable mutex order checking.
Changed names of the nonposix mutex_init functions to not conflict with my_phread_mutex_init()
Added and extended structures for mutex deadlock detection.
New arguments to sage_mutex_init() and safe_mutex_lock() to allow one to disable mutex order checking.
Added variable 'safe_mutex_deadlock_detector' to enable/disable deadlock detection for all pthread_mutex_init()
mysys/Makefile.am:
Added cleaning of test files
Added test_thr_mutex
mysys/hash.c:
Added hash_iterate() to iterate over all elements in a hash
More comments
mysys/my_init.c:
Added calls to destory all mutex uses by mysys()
Added waiting for threads to end before calling TERMINATE() to list not freed memory
mysys/my_pthread.c:
Changed names to free my_pthread_mutex_init() for mutex-lock-order-checking
mysys/my_sleep.c:
Fixed too long wait if using 1000000L as argument
mysys/my_thr_init.c:
Mark THR_LOCK_threads and THR_LOCK_malloc to not have mutex deadlock detection.
(We can't have it enabled for this as these are internal mutex used by the detector
Call my_thread_init() early as we need thread specific variables enabled for the following pthread_mutex_init()
Move code to wait for threads to end to my_wait_for_other_threads_to_die()
Don't destroy mutex and conditions unless all threads have died
Added my_thread_destroy_mutex() to destroy all mutex used by the mysys thread system
Name the thread specific mutex as "mysys_var->mutex"
Added my_thread_var_mutex_in_use() to return pointer to mutex in use or 0 if thread variables are not initialized
mysys/mysys_priv.h:
Added prototypes for functions used internally with mutex-wrong-usage detection
mysys/thr_mutex.c:
Added runtime detection of mutex used in conflicting order
See WL#3262 or test_thr_mutex.c for examples
The base idea is for each mutex have two hashes:
- mutex->locked_mutex points to all mutex used after this one
- mutex->used_mutex points to all mutex which has this mutex in it's mutex->locked_mutex
There is a wrong mutex order if any mutex currently locked before this mutex is in the mutex->locked_mutex hash
sql/event_queue.cc:
Mark mutex used inconsistently (need to be fixed by server team)
sql/event_scheduler.cc:
Declare the right order to take the mutex
sql/events.cc:
Mark mutex used inconsistently (need to be fixed by server team)
sql/ha_ndbcluster_binlog.cc:
Mark mutex used inconsistently (need to be fixed by server team)
sql/log.cc:
Mark mutex used inconsistently (need to be fixed by server team)
sql/mysqld.cc:
Use pthread_mutex_trylock instead of pthread_mutex_unlock() when sending kill signal to thread
This is needed to avoid wrong mutex order as normally one takes 'current_mutex' before mysys_var->mutex.
Added call to free sp cache.
Add destruction of LOCK_server_started and COND_server_started.
Added register_mutex_order() function to register in which order mutex should be taken
(to initiailize mutex_deadlock_detector).
Added option to turn off safe_mutex_deadlock_detector
sql/protocol.cc:
Fixed wrong argument to DBUG_PRINT (found by valgrind)
sql/rpl_mi.cc:
Mark mutex used inconsistently (need to be fixed by server team)
sql/set_var.cc:
Remove wrong locking of LOCK_global_system_variables when reading and setting log variables
(would cause inconsistent mutex order).
Update global variables outside of logger.unlock() as LOCK_global_system_variables has to be taken before logger locks
Reviewed by gluh
sql/sp_cache.cc:
Added function to destroy mutex used by sp cache
sql/sp_cache.h:
Added function to destroy mutex used by sp cache
sql/sql_class.cc:
Use pthread_mutex_trylock instead of pthread_mutex_unlock() when sending kill signal to thread
This is needed to avoid wrong mutex order as normally one takes 'current_mutex' before mysys_var->mutex.
Register order in which LOCK_delete and mysys_var->mutex is taken
sql/sql_insert.cc:
Give a name for Delayed_insert::mutex
Mark mutex used inconsistently (need to be fixed by server team)
Move closing of tables outside of di->mutex (to avoid wrong mutex order)
sql/sql_show.cc:
Don't keep LOCK_global_system_variables locked over value->show_type() as this leads to wrong mutex order
storage/innobase/handler/ha_innodb.cc:
Disable safe_muted_deadlock_detector for innobase intern mutex (to speed up page cache initialization)
storage/maria/ha_maria.cc:
Added flag to ha_maria::info() to signal if we need to lock table share or not.
This is needed to avoid locking mutex in wrong order
storage/maria/ha_maria.h:
Added flag to ha_maria::info() to signal if we need to lock table share or not.
storage/maria/ma_close.c:
Destroy key_del_lock
Simplify freeing ftparser_param
storage/maria/ma_key.c:
Better comment
storage/maria/ma_loghandler.c:
Mark mutex used inconsistently (need to be fixed by sanja)
storage/maria/ma_state.c:
More comments
storage/maria/ma_test1.c:
Ensure that safe_mutex_deadlock_detector is always on (should be, this is just for safety)
storage/maria/ma_test2.c:
Ensure that safe_mutex_deadlock_detector is always on (should be, this is just for safety)
japanese characters.
Fix - removed obsolvete setlocale from my_init.c . In MBCS
environments it caused unwanted character-to-byte translations
in fputc() in client code and wrong output as result.
into pilot.mysql.com:/data/msvensson/mysql/mysql-5.1-mtr
BitKeeper/etc/ignore:
auto-union
BitKeeper/deleted/.del-rpl_row_charset.test:
Auto merged
CMakeLists.txt:
Auto merged
configure.in:
Auto merged
client/mysqltest.c:
Auto merged
mysql-test/extra/binlog_tests/blackhole.test:
Auto merged
mysql-test/include/commit.inc:
Auto merged
mysql-test/include/mix1.inc:
Auto merged
mysql-test/lib/mtr_report.pm:
Auto merged
mysql-test/r/commit_1innodb.result:
Auto merged
mysql-test/r/create.result:
Auto merged
mysql-test/r/ctype_big5.result:
Auto merged
mysql-test/r/drop.result:
Auto merged
mysql-test/r/group_by.result:
Auto merged
mysql-test/r/information_schema.result:
Auto merged
mysql-test/r/loaddata.result:
Auto merged
mysql-test/r/mysqlbinlog.result:
Auto merged
mysql-test/r/partition_error.result:
Auto merged
mysql-test/r/query_cache.result:
Auto merged
mysql-test/r/sp.result:
Auto merged
mysql-test/r/view.result:
Auto merged
mysql-test/r/warnings.result:
Auto merged
mysql-test/suite/binlog/r/binlog_row_mix_innodb_myisam.result:
Auto merged
mysql-test/suite/binlog/r/binlog_stm_blackhole.result:
Auto merged
mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result:
Auto merged
mysql-test/suite/binlog/r/binlog_unsafe.result:
Auto merged
mysql-test/suite/binlog/t/binlog_unsafe.test:
Auto merged
mysql-test/suite/federated/federated.result:
Auto merged
mysql-test/suite/federated/federated.test:
Auto merged
mysql-test/suite/parts/r/partition_alter1_myisam.result:
Auto merged
mysql-test/suite/parts/r/partition_alter2_myisam.result:
Auto merged
mysql-test/suite/rpl/r/rpl_row_basic_11bugs.result:
Auto merged
mysql-test/suite/rpl/r/rpl_row_log.result:
Auto merged
mysql-test/suite/rpl/r/rpl_row_log_innodb.result:
Auto merged
mysql-test/suite/rpl/t/disabled.def:
Auto merged
mysql-test/suite/rpl/t/rpl_flushlog_loop.test:
Auto merged
mysql-test/suite/rpl_ndb/r/rpl_ndb_log.result:
Auto merged
mysql-test/suite/rpl_ndb/t/rpl_ndb_transaction.test:
Auto merged
mysql-test/t/create.test:
Auto merged
mysql-test/t/csv.test:
Auto merged
mysql-test/t/disabled.def:
Auto merged
mysql-test/t/distinct.test:
Auto merged
mysql-test/t/drop.test:
Auto merged
mysql-test/t/group_by.test:
Auto merged
mysql-test/t/innodb.test:
Auto merged
mysql-test/t/loaddata.test:
Auto merged
mysql-test/t/partition_error.test:
Auto merged
mysql-test/t/query_cache.test:
Auto merged
mysql-test/t/sp.test:
Auto merged
mysql-test/t/view.test:
Auto merged
mysql-test/t/warnings.test:
Auto merged
sql/ha_ndbcluster.cc:
Auto merged
BitKeeper/deleted/.del-combinations:
Delete: mysql-test/suite/binlog/combinations
mysql-test/r/partition_not_windows.result:
Use remote
mysql-test/r/partition_symlink.result:
Use remote
mysql-test/r/symlink.result:
SCCS merged
mysql-test/suite/parts/inc/partition_basic.inc:
SCCS merged
mysql-test/suite/parts/inc/partition_check_drop.inc:
Use remote
mysql-test/suite/parts/inc/partition_layout_check1.inc:
Use remote
mysql-test/suite/parts/inc/partition_layout_check2.inc:
Use remote
mysql-test/suite/parts/r/partition_basic_innodb.result:
Use remote
mysql-test/suite/parts/r/partition_basic_myisam.result:
Use remote
mysql-test/suite/parts/r/partition_engine_myisam.result:
Use remote
mysql-test/suite/parts/t/partition_sessions.test:
SCCS merged
mysql-test/t/partition.test:
SCCS merged
mysql-test/t/partition_not_windows.test:
Use remote
mysql-test/t/partition_symlink.test:
Use remote
mysql-test/t/symlink.test:
Use remote
mysql-test/suite/binlog/r/binlog_multi_engine.result:
Manual merge, name of binlog file changed
mysql-test/suite/rpl/t/rpl_row_mysqlbinlog.test:
Manual merge
mysys/my_init.c:
Manual merge
- Fix 'my_win_init' code that handles initialization of
"query_performance_counter" and conversion from registry values to
environment strings
mysys/my_init.c:
- Change check of return value from 'QueryPerformanceFrequency', it
returns 0 on error
- Don't return from 'my_win_init' if the registry
key "HKEY_LOCAL_MACHINE\SOFTWARE\MySQL" doesn't exist. This caused
the initialization of "query_performance_counter" to be bypassed unless there
was at lest such a key.
- Cleanup the "registry -> environment variables" from Italian comments,
remove redundant variables and fix style.
- Remove function 'setEnvString' and replace it with oneliner 'strxmov'
Automaticly disable ma_test_recovery if not compiled with debugging. This fixes that make test works in Maria.
Fixed wrong merge of ma_init.c from 5.1
Portability fixes:
- Use my_chmod() instead of my_chmod()
- Use my_access() instead of my_stat() to test if file exists
- Don't test result value of pthread_mutex_lock() and pthread_mutex_unlock() as this is not portable
- No reason to test if file exists before we delete it
include/my_sys.h:
Added my_chmod
include/mysys_err.h:
Added error for my_chmod
mysys/Makefile.am:
Added my_chmod
mysys/errors.c:
Added error for my_chmod
mysys/my_init.c:
Syncronize with 5.1 to fix setting of QueryPerformanceFrequency()
storage/maria/ma_test1.c:
Changed short option of --skip-delete and --skip-update to be more logical
storage/maria/ma_test_recovery.expected:
Updated results after adding more tests
storage/maria/ma_test_recovery:
Abort test nicely if we are runnning without debugging
Added more tests
Changed temporary file names so that one can run maria_chk on them
Removed some old comments
storage/maria/maria_read_log.c:
Added note if maria_read_log will not be able to create byte-to-byte identical tables compared to normal execution
storage/maria/unittest/ma_pagecache_consist.c:
Removed wrong setting of buff that caused memory overwrite
Use my_chmod() instead of chmod()
Don't test result value of pthread_mutex_lock() and pthread_mutex_unlock() as this is not portable
storage/maria/unittest/ma_pagecache_single.c:
Use my_chmod() instead of chmod()
Don't test result value of pthread_mutex_lock() and pthread_mutex_unlock() as this is not portable
storage/maria/unittest/ma_test_loghandler_first_lsn-t.c:
No reason to test if file exists before we delete it
storage/maria/unittest/ma_test_loghandler_multithread-t.c:
Don't test result value of pthread_mutex_lock() and pthread_mutex_unlock() as this is not portable
storage/maria/unittest/ma_test_loghandler_noflush-t.c:
No reason to test if file exists before we delete it
storage/maria/unittest/ma_test_loghandler_nologs-t.c:
Use my_access() instead of my_stat() to test if file exists
storage/maria/unittest/ma_test_loghandler_pagecache-t.c:
No reason to test if file exists before we delete it
chmod -> my_chmod
mysys/my_chmod.c:
Added wrapper for chmod()
