diff options
| author | Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> | 2023-01-12 10:58:53 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2023-02-01 08:42:11 -0300 |
| commit | 98f9435f336cbee5d57a1a16373331ca1bc648db (patch) | |
| tree | f6e57c478194afb2323db3cba00db96e7582164b /sysdeps | |
| parent | 1e442efd57f231bf76030d7a30f2095d1261db20 (diff) | |
| download | glibc-98f9435f336cbee5d57a1a16373331ca1bc648db.zip glibc-98f9435f336cbee5d57a1a16373331ca1bc648db.tar.gz glibc-98f9435f336cbee5d57a1a16373331ca1bc648db.tar.bz2 | |
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 <carlos@redhat.com>
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/unix/sysv/linux/clone-internal.c | 24 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/kernel-features.h | 9 |
2 files changed, 32 insertions, 1 deletions
diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c index e125c91..790739c 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; diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h index a23d007..4b5c4af 100644 --- a/sysdeps/unix/sysv/linux/kernel-features.h +++ b/sysdeps/unix/sysv/linux/kernel-features.h @@ -241,4 +241,13 @@ # define __ASSUME_FUTEX_LOCK_PI2 0 #endif +/* The clone3 system call was introduced across on most architectures in + Linux 5.3. Not all ports implements it, so it should be used along + HAVE_CLONE3_WRAPPER define. */ +#if __LINUX_KERNEL_VERSION >= 0x050300 +# define __ASSUME_CLONE3 1 +#else +# define __ASSUME_CLONE3 0 +#endif + #endif /* kernel-features.h */ |