From: Carlos O'Donell <carlos@redhat.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>,
libc-alpha@sourceware.org, Szabolcs Nagy <szabolcs.nagy@arm.com>,
"H . J . Lu" <hjl.tools@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Subject: Re: [PATCH v2 11/11] Linux: optimize clone3 internal usage
Date: Wed, 11 Jan 2023 16:45:10 -0500 [thread overview]
Message-ID: <d731a762-55b3-9636-4ff4-60ff8089263b@redhat.com> (raw)
In-Reply-To: <20221104190112.2566409-12-adhemerval.zanella@linaro.org>
On 11/4/22 15:01, Adhemerval Zanella via Libc-alpha wrote:
> 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.
Please see original v2 review. Please post v4.
> ---
> include/clone_internal.h | 5 +++++
> sysdeps/unix/sysv/linux/clone-internal.c | 24 ++++++++++++++++++++++-
> sysdeps/unix/sysv/linux/kernel-features.h | 9 +++++++++
> 3 files changed, 37 insertions(+), 1 deletion(-)
>
> 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 */
--
Cheers,
Carlos.
next prev parent reply other threads:[~2023-01-11 21:45 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-04 19:01 [PATCH v2 00/11] Optimize posix_spawn signal setup with clone3 Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 01/11] linux: Do not reset signal handler in posix_spawn if it is already SIG_DFL Adhemerval Zanella
2023-01-11 21:27 ` Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 02/11] linux: Extend internal clone3 documentation Adhemerval Zanella
2022-11-07 16:40 ` Szabolcs Nagy
2023-01-11 21:35 ` Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 03/11] Linux: Do not align the stack for __clone3 Adhemerval Zanella
2023-01-11 21:43 ` Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 04/11] linux: Add clone3 CLONE_CLEAR_SIGHAND optimization to posix_spawn Adhemerval Zanella
2023-01-11 21:44 ` Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 05/11] powerpc64: Add the clone3 wrapper Adhemerval Zanella
2022-11-28 16:38 ` Paul E Murphy
2022-11-29 20:43 ` Adhemerval Zanella Netto
2022-11-04 19:01 ` [PATCH v2 06/11] aarch64: " Adhemerval Zanella
2022-11-07 16:14 ` Szabolcs Nagy
2022-11-04 19:01 ` [PATCH v2 07/11] s390x: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 08/11] riscv: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 09/11] arm: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 10/11] mips: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 11/11] Linux: optimize clone3 internal usage Adhemerval Zanella
2023-01-11 21:45 ` Carlos O'Donell [this message]
2023-01-11 21:24 ` [PATCH v2 00/11] Optimize posix_spawn signal setup with clone3 Carlos O'Donell
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