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Fix a potential race condition. Fix a couple of places where

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_glapi_DispatchTSD wasn't properly handled.
This commit is contained in:
Ian Romanick 2004-07-02 00:01:09 +00:00
parent 2491d5135b
commit d14d103a0c
1 changed files with 26 additions and 13 deletions
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39
src/mesa/glapi/glapi.c
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@ -155,10 +155,15 @@ static int NoOpUnused(void)
* static dispatch functions to call \c _glapi_get_dispatch to get the real
* dispatch table.
*
* Throughout the code \c _glapi_DispatchTSD == \c NULL is used to determine
* whether or not the application is multi-threaded.
* There is a race condition in setting \c _glapi_DispatchTSD to \c NULL.
* It is possible for the original thread to be setting it at the same instant
* a new thread, perhaps running on a different processor, is clearing it.
* Because of that, \c ThreadSafe, which can only ever be changed to
* \c GL_FALSE, is used to determin whether or not the application is
* multithreaded.
*/
/*@{*/
static GLboolean ThreadSafe = GL_FALSE; /**< In thread-safe mode? */
_glthread_TSD _gl_DispatchTSD; /**< Per-thread dispatch pointer */
static _glthread_TSD RealDispatchTSD; /**< only when using override */
static _glthread_TSD ContextTSD; /**< Per-thread context pointer */
@ -184,9 +189,12 @@ static int glUnused(void)
struct _glapi_table *_glapi_Dispatch = (struct _glapi_table *) __glapi_noop_table;
#if defined( THREADS )
struct _glapi_table *_glapi_DispatchTSD = (struct _glapi_table *) __glapi_noop_table;
#endif
struct _glapi_table *_glapi_RealDispatch = (struct _glapi_table *) __glapi_noop_table;
/* Used when thread safety disabled */
void *_glapi_Context = NULL;
@ -219,7 +227,7 @@ void
_glapi_check_multithread(void)
{
#if defined(THREADS)
if ( _glapi_DispatchTSD != NULL ) {
if (!ThreadSafe) {
static unsigned long knownID;
static GLboolean firstCall = GL_TRUE;
if (firstCall) {
@ -227,6 +235,7 @@ _glapi_check_multithread(void)
firstCall = GL_FALSE;
}
else if (knownID != _glthread_GetID()) {
ThreadSafe = GL_TRUE;
_glapi_set_dispatch(NULL);
}
}
@ -249,7 +258,7 @@ _glapi_set_context(void *context)
{
#if defined(THREADS)
_glthread_SetTSD(&ContextTSD, context);
_glapi_Context = (_glapi_DispatchTSD == NULL) ? NULL : context;
_glapi_Context = (ThreadSafe) ? NULL : context;
#else
_glapi_Context = context;
#endif
@ -266,7 +275,7 @@ void *
_glapi_get_context(void)
{
#if defined(THREADS)
if ( _glapi_DispatchTSD == NULL ) {
if (ThreadSafe) {
return _glthread_GetTSD(&ContextTSD);
}
else {
@ -303,7 +312,7 @@ _glapi_set_dispatch(struct _glapi_table *dispatch)
#if defined(THREADS)
if (DispatchOverride) {
_glthread_SetTSD(&RealDispatchTSD, (void *) old_style_dispatch);
if ( dispatch == NULL )
if (ThreadSafe)
_glapi_RealDispatch = (struct _glapi_table*) __glapi_threadsafe_table;
else
_glapi_RealDispatch = dispatch;
@ -311,11 +320,14 @@ _glapi_set_dispatch(struct _glapi_table *dispatch)
else {
/* normal operation */
_glthread_SetTSD(&_gl_DispatchTSD, (void *) old_style_dispatch);
_glapi_DispatchTSD = dispatch;
_glapi_Dispatch = (dispatch == NULL)
? (struct _glapi_table *) __glapi_threadsafe_table
: old_style_dispatch;
if (ThreadSafe) {
_glapi_Dispatch = (struct _glapi_table *) __glapi_threadsafe_table;
_glapi_DispatchTSD = NULL;
}
else {
_glapi_Dispatch = old_style_dispatch;
_glapi_DispatchTSD = dispatch;
}
}
#else /*THREADS*/
if (DispatchOverride) {
@ -336,7 +348,7 @@ struct _glapi_table *
_glapi_get_dispatch(void)
{
#if defined(THREADS)
if ( _glapi_DispatchTSD == NULL ) {
if (ThreadSafe) {
if (DispatchOverride) {
return (struct _glapi_table *) _glthread_GetTSD(&RealDispatchTSD);
}
@ -394,8 +406,9 @@ _glapi_begin_dispatch_override(struct _glapi_table *override)
#if defined(THREADS)
_glthread_SetTSD(&_gl_DispatchTSD, (void *) override);
if ( _glapi_DispatchTSD == NULL ) {
if ( ThreadSafe ) {
_glapi_Dispatch = (struct _glapi_table *) __glapi_threadsafe_table;
_glapi_DispatchTSD = NULL;
}
else {
_glapi_Dispatch = override;