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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2022-09-28 10:24:06 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2022-11-29 18:19:31 -0300 |
| commit | c644b43efe494c57a58aa532d4686375d5e6ecbf (patch) | |
| tree | c98a856ad0f7c8d71f6c278edc21726663c6c0e4 | |
| parent | 1aa2f565f8911f407bed88d7f7372b80aca54871 (diff) | |
| download | glibc-azanella/posix_spawn-clone3.tar.gz glibc-azanella/posix_spawn-clone3.tar.xz glibc-azanella/posix_spawn-clone3.zip | |
Linux: optimize clone3 internal usage azanella/posix_spawn-clone3
Now that clone3 is used on more architectures, add an optimization to avoid calling when glibc detects that it is no supported by the kernel. It also adds __ASSUME_CLONE3, which allows skip this optimization and issue 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.
| -rw-r--r-- | include/clone_internal.h | 5 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/clone-internal.c | 24 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/kernel-features.h | 9 |
3 files changed, 37 insertions, 1 deletions
diff --git a/include/clone_internal.h b/include/clone_internal.h index 81292b3eb1..5f936dd8dc 100644 --- a/include/clone_internal.h +++ b/include/clone_internal.h @@ -26,6 +26,11 @@ extern int __clone3 (struct clone_args *__cl_args, size_t __size, fall back to clone or clone2. */ extern int __clone_internal (struct clone_args *__cl_args, int (*__func) (void *__arg), void *__arg); +/* clone3 wrapper with a sticky check to avoid re-issue the syscall if + it 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), diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c index 7bc991e033..39d76733db 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 74adc3956b..4ecd08a98f 100644 --- a/sysdeps/unix/sysv/linux/kernel-features.h +++ b/sysdeps/unix/sysv/linux/kernel-features.h @@ -236,4 +236,13 @@ # 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 */ |