From 98f9435f336cbee5d57a1a16373331ca1bc648db Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Netto Date: Thu, 12 Jan 2023 10:58:53 -0300 Subject: Linux: optimize clone3 internal usage Add an optimization to avoid calling clone3 when glibc detects that there is no kernel support. It also adds __ASSUME_CLONE3, which allows skipping this optimization and issuing the clone3 syscall directly. It does not handle the the small window between 5.3 and 5.5 for posix_spawn (CLONE_CLEAR_SIGHAND was added in 5.5). Checked on x86_64-linux-gnu. Reviewed-by: Carlos O'Donell --- sysdeps/unix/sysv/linux/clone-internal.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) (limited to 'sysdeps/unix/sysv/linux/clone-internal.c') diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c index e125c9125e..790739cfce 100644 --- a/sysdeps/unix/sysv/linux/clone-internal.c +++ b/sysdeps/unix/sysv/linux/clone-internal.c @@ -76,6 +76,28 @@ __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, @@ -83,7 +105,7 @@ __clone_internal (struct clone_args *cl_args, { #ifdef HAVE_CLONE3_WRAPPER 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; -- cgit v1.2.3-70-g09d2