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Fixed bug 4579 - SDL_android.c s_active not being atomic

Isaias Brunet

This bug cause a false assert due to multiple threads modifying the same variable without any atomic operation.
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slouken committed Apr 5, 2019
1 parent 9eac91d commit a46af76b076ad570690bf82d8f9c96ce0bc31c4b
Showing with 9 additions and 4 deletions.
  1. +9 −4 src/core/android/SDL_android.c
@@ -1156,7 +1156,7 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeSetenv)(
Functions called by SDL into Java
*******************************************************************************/

static int s_active = 0;
static SDL_atomic_t s_active;
struct LocalReferenceHolder
{
JNIEnv *m_env;
@@ -1181,7 +1181,7 @@ static SDL_bool LocalReferenceHolder_Init(struct LocalReferenceHolder *refholder
SDL_SetError("Failed to allocate enough JVM local references");
return SDL_FALSE;
}
++s_active;
SDL_AtomicIncRef(&s_active);
refholder->m_env = env;
return SDL_TRUE;
}
@@ -1194,10 +1194,15 @@ static void LocalReferenceHolder_Cleanup(struct LocalReferenceHolder *refholder)
if (refholder->m_env) {
JNIEnv *env = refholder->m_env;
(*env)->PopLocalFrame(env, NULL);
--s_active;
SDL_AtomicDecRef(&s_active);
}
}

static SDL_bool LocalReferenceHolder_IsActive(void)
{
return (SDL_AtomicGet(&s_active) > 0);
}

ANativeWindow* Android_JNI_GetNativeWindow(void)
{
ANativeWindow *anw = NULL;
@@ -1601,7 +1606,7 @@ static SDL_bool Android_JNI_ExceptionOccurred(SDL_bool silent)
jthrowable exception;

/* Detect mismatch LocalReferenceHolder_Init/Cleanup */
SDL_assert((s_active > 0));
SDL_assert(LocalReferenceHolder_IsActive());

exception = (*env)->ExceptionOccurred(env);
if (exception != NULL) {

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