@@ -7,6 +7,11 @@ extern __typeof (clone3) __clone3;
-1 with ENOSYS, fall back to clone or clone2. */
extern int __clone_internal (struct clone_args *__cl_args,
int (*__func) (void *__arg), void *__arg);
+/* clone3 wrapper that avoid issuing the syscall once clone3 fails with
+ ENOSYS. */
+extern int __clone3_internal (struct clone_args *cl_args,
+ int (*func) (void *args), void *arg)
+ attribute_hidden;
/* The fallback code which calls clone/clone2 based on clone3 arguments. */
extern int __clone_internal_fallback (struct clone_args *__cl_args,
int (*__func) (void *__arg),
@@ -76,6 +76,29 @@ __clone_internal_fallback (struct clone_args *cl_args,
return ret;
}
+int
+__clone3_internal (struct clone_args *cl_args, int (*func) (void *args),
+ void *arg)
+{
+#ifdef HAVE_CLONE3_WRAPPER
+# if __ASSUME_CLONE3
+ return __clone3 (cl_args, sizeof (*cl_args), func, arg);
+# else
+ static int clone3_supported = 1;
+ if (atomic_load_relaxed (&clone3_supported) == 1)
+ {
+ int ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
+ if (ret != -1 || errno != ENOSYS)
+ return ret;
+
+ atomic_store_relaxed (&clone3_supported, 0);
+ }
+# endif
+#endif
+ __set_errno (ENOSYS);
+ return -1;
+}
+
int
__clone_internal (struct clone_args *cl_args,
@@ -84,7 +107,7 @@ __clone_internal (struct clone_args *cl_args,
#ifdef HAVE_CLONE3_WRAPPER
/* Try clone3 first. */
int saved_errno = errno;
- int ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
+ int ret = __clone3_internal (cl_args, func, arg);
if (ret != -1 || errno != ENOSYS)
return ret;
@@ -236,4 +236,12 @@
# define __ASSUME_FUTEX_LOCK_PI2 0
#endif
+/* The clone3 system call was introduced across all architectures
+ in Linux 5.3. */
+#if __LINUX_KERNEL_VERSION >= 0x050300
+# define __ASSUME_CLONE3 1
+#else
+# define __ASSUME_CLONE3 0
+#endif
+
#endif /* kernel-features.h */