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LibC: Fix pthread cancellation

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Install SIGCANCEL handler for all threads.

Remove unneeded atomic stores and loads. States are only changed within
the thread itself.

Define pthread_testcancel as a macro so it gets inlined inside
cancellation points
This commit is contained in:
Bananymous
2026-04-06 19:30:01 +03:00
parent 3fb903d991
commit 7fb27b16e8
2 changed files with 28 additions and 24 deletions
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42
userspace/libraries/LibC/pthread.cpp
View File

@@ -22,6 +22,22 @@ struct pthread_trampoline_info_t
void* arg;
};
static void _pthread_cancel_handler(int)
{
uthread* uthread = _get_uthread();
uthread->canceled = true;
if (uthread->cancel_state == PTHREAD_CANCEL_DISABLE)
return;
if (uthread->cancel_type == PTHREAD_CANCEL_ASYNCHRONOUS)
pthread_exit(PTHREAD_CANCELED);
}
__attribute__((constructor))
static void _install_main_thread_cancel_handler()
{
signal(SIGCANCEL, &_pthread_cancel_handler);
}
// stack is 16 byte aligned on entry, this `call` is used to align it
extern "C" void _pthread_trampoline(void*);
asm(
@@ -54,6 +70,7 @@ extern "C" void _pthread_trampoline_cpp(void* arg)
#error
#endif
free(arg);
signal(SIGCANCEL, &_pthread_cancel_handler);
pthread_exit(info.start_routine(info.arg));
ASSERT_NOT_REACHED();
}
@@ -610,25 +627,8 @@ int pthread_atfork(void (*prepare)(void), void (*parent)(void), void(*child)(voi
return 0;
}
static void pthread_cancel_handler(int)
{
uthread* uthread = _get_uthread();
BAN::atomic_store(uthread->canceled, true);
if (BAN::atomic_load(uthread->cancel_state) != PTHREAD_CANCEL_ENABLE)
return;
switch (BAN::atomic_load(uthread->cancel_type))
{
case PTHREAD_CANCEL_ASYNCHRONOUS:
pthread_exit(PTHREAD_CANCELED);
case PTHREAD_CANCEL_DEFERRED:
return;
}
ASSERT_NOT_REACHED();
}
int pthread_cancel(pthread_t thread)
{
signal(SIGCANCEL, &pthread_cancel_handler);
return pthread_kill(thread, SIGCANCEL);
}
@@ -666,14 +666,10 @@ int pthread_setcanceltype(int type, int* oldtype)
return 0;
}
#undef pthread_testcancel
void pthread_testcancel(void)
{
uthread* uthread = _get_uthread();
if (BAN::atomic_load(uthread->cancel_state) != PTHREAD_CANCEL_ENABLE)
return;
if (!BAN::atomic_load(uthread->canceled))
return;
pthread_exit(PTHREAD_CANCELED);
_pthread_testcancel();
}
int pthread_getschedparam(pthread_t thread, int* __restrict policy, struct sched_param* __restrict param)