Commit 7ca59827 authored by John Koleszar's avatar John Koleszar Committed by Gerrit Code Review
Browse files

Merge "rtcd/win32: use InitializeCriticalSection explicitly"

parents ea90cee2 9bbab8e4
......@@ -13,17 +13,43 @@
#if CONFIG_MULTITHREAD && defined(_WIN32)
#include <windows.h>
#include <stdlib.h>
static void once(void (*func)(void))
{
/* Using a static initializer here rather than InitializeCriticalSection()
* since there's no race-free context in which to execute it. Protecting
* it with an atomic op like InterlockedCompareExchangePointer introduces
* an x86 dependency, and InitOnceExecuteOnce requires Vista.
*/
static CRITICAL_SECTION lock = {(void *)-1, -1, 0, 0, 0, 0};
static CRITICAL_SECTION *lock;
static LONG waiters;
static int done;
void *lock_ptr = &lock;
/* If the initialization is complete, return early. This isn't just an
* optimization, it prevents races on the destruction of the global
* lock.
*/
if(done)
return;
InterlockedIncrement(&waiters);
EnterCriticalSection(&lock);
/* Get a lock. We create one and try to make it the one-true-lock,
* throwing it away if we lost the race.
*/
{
/* Scope to protect access to new_lock */
CRITICAL_SECTION *new_lock = malloc(sizeof(CRITICAL_SECTION));
InitializeCriticalSection(new_lock);
if (InterlockedCompareExchangePointer(lock_ptr, new_lock, NULL) != NULL)
{
DeleteCriticalSection(new_lock);
free(new_lock);
}
}
/* At this point, we have a lock that can be synchronized on. We don't
* care which thread actually performed the allocation.
*/
EnterCriticalSection(lock);
if (!done)
{
......@@ -31,7 +57,17 @@ static void once(void (*func)(void))
done = 1;
}
LeaveCriticalSection(&lock);
LeaveCriticalSection(lock);
/* Last one out should free resources. The destructed objects are
* protected by checking if(done) above.
*/
if(!InterlockedDecrement(&waiters))
{
DeleteCriticalSection(lock);
free(lock);
lock = NULL;
}
}
......
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