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MDEV-11896 thd_get_error_context_description race condition

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Change the semantics of thd_get_error_context_description().
It no longer expects the caller to lock LOCK_thread_count
(no caller ever did that anyway), but takes care of it internally.
This commit is contained in:
Sergei Golubchik
2017-07-19 19:47:38 +02:00
parent da2a838628
commit dc8b2fb03a
2 changed files with 5 additions and 7 deletions
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2
include/service_versions.h
View File

@ -31,4 +31,4 @@
#define VERSION_my_sha1 0x0100 #define VERSION_my_sha1 0x0100
#define VERSION_logger 0x0100 #define VERSION_logger 0x0100
#define VERSION_thd_autoinc 0x0100 #define VERSION_thd_autoinc 0x0100
#define VERSION_thd_error_context 0x0100 #define VERSION_thd_error_context 0x0200

10
sql/sql_class.cc
View File

@ -725,12 +725,6 @@ extern "C"
@param buffer pointer to preferred result buffer @param buffer pointer to preferred result buffer
@param length length of buffer @param length length of buffer
@param max_query_len how many chars of query to copy (0 for all) @param max_query_len how many chars of query to copy (0 for all)
@req LOCK_thread_count
@note LOCK_thread_count mutex is not necessary when the function is invoked on
the currently running thread (current_thd) or if the caller in some other
way guarantees that access to thd->query is serialized.
@return Pointer to string @return Pointer to string
*/ */
@ -744,6 +738,9 @@ char *thd_get_error_context_description(THD *thd, char *buffer,
const Security_context *sctx= &thd->main_security_ctx; const Security_context *sctx= &thd->main_security_ctx;
char header[256]; char header[256];
int len; int len;
mysql_mutex_lock(&LOCK_thread_count);
/* /*
The pointers thd->query and thd->proc_info might change since they are The pointers thd->query and thd->proc_info might change since they are
being modified concurrently. This is acceptable for proc_info since its being modified concurrently. This is acceptable for proc_info since its
@ -799,6 +796,7 @@ char *thd_get_error_context_description(THD *thd, char *buffer,
} }
mysql_mutex_unlock(&thd->LOCK_thd_data); mysql_mutex_unlock(&thd->LOCK_thd_data);
} }
mysql_mutex_unlock(&LOCK_thread_count);
if (str.c_ptr_safe() == buffer) if (str.c_ptr_safe() == buffer)
return buffer; return buffer;