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BUG#29968 (rpl_ndb_circular.test and rpl_ndb_log.test fail):

Browse source 
Removing unguarded read of slave_running field from inside
terminate_slave_threads(). This could cause premature exit in the event
that the slave thread already were shutting down, but isn't finished yet.

The fields slave_running, io_thd, and sql_thread are guarded by an
associated run_lock. A read of these fields were not guarded inside
terminate_slave_threads(), which caused an assertion to fire. The
assertion was removed, and the code reorganized slightly.


sql/slave.cc:
  Changing signature of terminate_slave_thread() to accept a skip_lock
  parameter instead of two mutexes. This mimics the signature of the
  terminate_slave_threads() function. Code is also changed as a result
  of this.
  
  Removing unguarded check of slave_running field in the master info and
  relay log info structure since that could cause premature exit of
  terminate_slave_threads().
  
  The thread variable for each of the slave threads can change before
  acquiring the run_lock mutex inside terminate_slave_thread(). Hence
  an assertion was removed that read the variable without guarding it
  with run_lock.
  
  Code that checked *slave_running status inside terminate_slave_thread()
  was reorganized slightly.
sql/slave.h:
  Moving terminate_slave_thread() to use internal linkage.
This commit is contained in:
unknown 2007-08-29 16:06:59 +02:00
parent cd7d837be6
commit e5c8240a7a
2 changed files with 64 additions and 31 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

91
sql/slave.cc
View file

@ -132,6 +132,11 @@ static int create_table_from_dump(THD* thd, MYSQL *mysql, const char* db,
const char* table_name, bool overwrite);
static int get_master_version_and_clock(MYSQL* mysql, MASTER_INFO* mi);
static Log_event* next_event(RELAY_LOG_INFO* rli);
static int terminate_slave_thread(THD *thd,
pthread_mutex_t* term_lock,
pthread_cond_t* term_cond,
volatile uint *slave_running,
bool skip_lock);
/*
Find out which replications threads are running
@ -312,35 +317,26 @@ int terminate_slave_threads(MASTER_INFO* mi,int thread_mask,bool skip_lock)
DBUG_RETURN(0); /* successfully do nothing */
int error,force_all = (thread_mask & SLAVE_FORCE_ALL);
pthread_mutex_t *sql_lock = &mi->rli.run_lock, *io_lock = &mi->run_lock;
pthread_mutex_t *sql_cond_lock,*io_cond_lock;
sql_cond_lock=sql_lock;
io_cond_lock=io_lock;
if (skip_lock)
{
sql_lock = io_lock = 0;
}
if ((thread_mask & (SLAVE_IO|SLAVE_FORCE_ALL)) && mi->slave_running)
if ((thread_mask & (SLAVE_IO|SLAVE_FORCE_ALL)))
{
DBUG_PRINT("info",("Terminating IO thread"));
mi->abort_slave=1;
if ((error=terminate_slave_thread(mi->io_thd,io_lock,
io_cond_lock,
&mi->stop_cond,
&mi->slave_running)) &&
&mi->slave_running,
skip_lock)) &&
!force_all)
DBUG_RETURN(error);
}
if ((thread_mask & (SLAVE_SQL|SLAVE_FORCE_ALL)) && mi->rli.slave_running)
if ((thread_mask & (SLAVE_SQL|SLAVE_FORCE_ALL)))
{
DBUG_PRINT("info",("Terminating SQL thread"));
DBUG_ASSERT(mi->rli.sql_thd != 0) ;
mi->rli.abort_slave=1;
if ((error=terminate_slave_thread(mi->rli.sql_thd,sql_lock,
sql_cond_lock,
&mi->rli.stop_cond,
&mi->rli.slave_running)) &&
&mi->rli.slave_running,
skip_lock)) &&
!force_all)
DBUG_RETURN(error);
}
@ -348,23 +344,60 @@ int terminate_slave_threads(MASTER_INFO* mi,int thread_mask,bool skip_lock)
}
int terminate_slave_thread(THD* thd, pthread_mutex_t* term_lock,
pthread_mutex_t *cond_lock,
pthread_cond_t* term_cond,
volatile uint *slave_running)
/**
Wait for a slave thread to terminate.
This function is called after requesting the thread to terminate
(by setting @c abort_slave member of @c Relay_log_info or @c
Master_info structure to 1). Termination of the thread is
controlled with the the predicate <code>*slave_running</code>.
Function will acquire @c term_lock before waiting on the condition
unless @c skip_lock is true in which case the mutex should be owned
by the caller of this function and will remain acquired after
return from the function.
@param term_lock
Associated lock to use when waiting for @c term_cond
@param term_cond
Condition that is signalled when the thread has terminated
@param slave_running
Pointer to predicate to check for slave thread termination
@param skip_lock
If @c true the lock will not be acquired before waiting on
the condition. In this case, it is assumed that the calling
function acquires the lock before calling this function.
@retval 0 All OK
*/
static int
terminate_slave_thread(THD *thd,
pthread_mutex_t* term_lock,
pthread_cond_t* term_cond,
volatile uint *slave_running,
bool skip_lock)
{
int error;
DBUG_ENTER("terminate_slave_thread");
if (term_lock)
{
if (!skip_lock)
pthread_mutex_lock(term_lock);
if (!*slave_running)
{
safe_mutex_assert_owner(term_lock);
if (!*slave_running)
{
if (!skip_lock)
pthread_mutex_unlock(term_lock);
DBUG_RETURN(ER_SLAVE_NOT_RUNNING);
}
DBUG_RETURN(ER_SLAVE_NOT_RUNNING);
}
DBUG_ASSERT(thd != 0);
THD_CHECK_SENTRY(thd);
/*
Is is critical to test if the slave is running. Otherwise, we might
be referening freed memory trying to kick it
@ -380,9 +413,13 @@ int terminate_slave_thread(THD* thd, pthread_mutex_t* term_lock,
*/
struct timespec abstime;
set_timespec(abstime,2);
pthread_cond_timedwait(term_cond, cond_lock, &abstime);
error= pthread_cond_timedwait(term_cond, term_lock, &abstime);
DBUG_ASSERT(error == ETIMEDOUT || error == 0);
}
if (term_lock)
DBUG_ASSERT(*slave_running == 0);
if (!skip_lock)
pthread_mutex_unlock(term_lock);
DBUG_RETURN(0);
}

4
sql/slave.h
View file

@ -133,10 +133,6 @@ bool flush_relay_log_info(RELAY_LOG_INFO* rli);
int register_slave_on_master(MYSQL* mysql);
int terminate_slave_threads(MASTER_INFO* mi, int thread_mask,
bool skip_lock = 0);
int terminate_slave_thread(THD* thd, pthread_mutex_t* term_mutex,
pthread_mutex_t* cond_lock,
pthread_cond_t* term_cond,
volatile uint* slave_running);
int start_slave_threads(bool need_slave_mutex, bool wait_for_start,
MASTER_INFO* mi, const char* master_info_fname,
const char* slave_info_fname, int thread_mask);