From 1515283c7f4f048ae4675dba993866ac3dd7a1ec Mon Sep 17 00:00:00 2001
From: Lubos Dolezel <lubos@dolezel.info>
Date: Wed, 18 Jul 2018 22:10:01 +0200
Subject: [PATCH] Short circuit the most common pthread_canceled() call for
 singlethreaded programs

---
 src/kernel/emulation/linux/bsdthread/bsdthread_create.c | 8 ++++++++
 src/kernel/emulation/linux/bsdthread/bsdthread_create.h | 3 +++
 src/kernel/emulation/linux/bsdthread/pthread_canceled.c | 5 +++++
 3 files changed, 16 insertions(+)

diff --git a/src/kernel/emulation/linux/bsdthread/bsdthread_create.c b/src/kernel/emulation/linux/bsdthread/bsdthread_create.c
index 582c01a88..fd674e37b 100644
--- a/src/kernel/emulation/linux/bsdthread/bsdthread_create.c
+++ b/src/kernel/emulation/linux/bsdthread/bsdthread_create.c
@@ -22,6 +22,8 @@ extern void *memset(void *s, int c, size_t n);
 
 #define STACK_GUARD_SIZE 4096
 
+static bool _uses_threads = false;
+
 // http://www.tldp.org/FAQ/Threads-FAQ/clone.c
 
 long sys_bsdthread_create(void* thread_start, void* arg,
@@ -31,6 +33,8 @@ long sys_bsdthread_create(void* thread_start, void* arg,
 	int ret;
 	unsigned long stacksize = 0;
 
+	_uses_threads = true;
+
 #ifndef BSDTHREAD_WRAP_LINUX_PTHREAD
 	if (!(flags & PTHREAD_START_CUSTOM))
 	{
@@ -123,4 +127,8 @@ int darling_thread_create(void** stack, void* entry_point, uintptr_t arg3,
 }
 #endif
 
+bool uses_threads(void)
+{
+	return _uses_threads;
+}
 
diff --git a/src/kernel/emulation/linux/bsdthread/bsdthread_create.h b/src/kernel/emulation/linux/bsdthread/bsdthread_create.h
index 82a72e362..24f85c4bb 100644
--- a/src/kernel/emulation/linux/bsdthread/bsdthread_create.h
+++ b/src/kernel/emulation/linux/bsdthread/bsdthread_create.h
@@ -1,6 +1,7 @@
 #ifndef BSDTHREAD_CREATE_H
 #define BSDTHREAD_CREATE_H
 #include <stdint.h>
+#include <stdbool.h>
 
 long sys_bsdthread_create(void* thread_start, void* arg, void** stack,
 		void* pthread, uint32_t flags);
@@ -10,6 +11,8 @@ int darling_thread_create(void** stack, void* entry_point, uintptr_t arg3,
 
 void* thread_stack_allocate(unsigned long stacksize);
 
+bool uses_threads(void);
+
 #define LINUX_CLONE_VM      0x00000100
 #define LINUX_CLONE_FS      0x00000200
 #define LINUX_CLONE_FILES   0x00000400
diff --git a/src/kernel/emulation/linux/bsdthread/pthread_canceled.c b/src/kernel/emulation/linux/bsdthread/pthread_canceled.c
index 673394839..3902441b6 100644
--- a/src/kernel/emulation/linux/bsdthread/pthread_canceled.c
+++ b/src/kernel/emulation/linux/bsdthread/pthread_canceled.c
@@ -5,9 +5,14 @@
 #include <stddef.h>
 #include "../mach/lkm.h"
 #include "../../../../lkm/api.h"
+#include "bsdthread_create.h"
+#include <sys/errno.h>
 
 long sys_pthread_canceled(int action)
 {
+	if (action == 0 && !uses_threads())
+		return -EINVAL;
+
 	int ret = lkm_call(NR_pthread_canceled, (void*)(long) action);
 	if (ret < 0)
 		ret = errno_linux_to_bsd(ret);