From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Christian Brauner <brauner@kernel.org>
Subject: [PATCH v2 9/9] Linux: optimize clone3 internal usage
Date: Fri, 30 Sep 2022 16:26:13 -0300 [thread overview]
Message-ID: <20220930192613.3491147-10-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20220930192613.3491147-1-adhemerval.zanella@linaro.org>
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.
---
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 320640e64b..385f3c5589 100644
--- a/include/clone_internal.h
+++ b/include/clone_internal.h
@@ -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 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 */
--
2.34.1
next prev parent reply other threads:[~2022-09-30 19:26 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-30 19:26 [PATCH v2 0/9] Optimize posix_spawn signal setup with clone3 Adhemerval Zanella
2022-09-30 19:26 ` [PATCH v2 1/9] linux: Do not reset signal handler in posix_spawn if it is already SIG_DFL Adhemerval Zanella
2023-01-11 21:06 ` Carlos O'Donell
2022-09-30 19:26 ` [PATCH v2 2/9] linux: Add clone3 CLONE_CLEAR_SIGHAND optimization to posix_spawn Adhemerval Zanella
2023-01-11 21:06 ` Carlos O'Donell
2022-09-30 19:26 ` [PATCH v2 3/9] powerpc64le: Add the clone3 wrapper Adhemerval Zanella
2022-09-30 19:26 ` [PATCH v2 4/9] aarch64: " Adhemerval Zanella
2022-11-02 12:12 ` Szabolcs Nagy
2022-11-03 13:15 ` Adhemerval Zanella Netto
2022-11-03 14:01 ` Szabolcs Nagy
2022-11-03 16:22 ` Adhemerval Zanella Netto
2022-11-03 16:31 ` Szabolcs Nagy
2022-11-03 16:39 ` Adhemerval Zanella Netto
2022-11-03 16:52 ` Szabolcs Nagy
2022-11-03 16:55 ` Adhemerval Zanella Netto
2022-11-03 20:55 ` H.J. Lu
2022-11-03 21:28 ` Adhemerval Zanella Netto
2022-11-03 21:22 ` Adhemerval Zanella Netto
2022-11-03 21:58 ` H.J. Lu
2022-11-04 12:32 ` Adhemerval Zanella Netto
2022-09-30 19:26 ` [PATCH v2 5/9] s390x: " Adhemerval Zanella
2022-09-30 19:26 ` [PATCH v2 6/9] riscv: " Adhemerval Zanella
2022-09-30 19:26 ` [PATCH v2 7/9] arm: " Adhemerval Zanella
2022-09-30 19:26 ` [PATCH v2 8/9] mips: " Adhemerval Zanella
2022-09-30 19:26 ` Adhemerval Zanella [this message]
2023-01-11 21:12 ` [PATCH v2 9/9] Linux: optimize clone3 internal usage Carlos O'Donell
2022-10-27 16:48 ` [PATCH v2 0/9] Optimize posix_spawn signal setup with clone3 Adhemerval Zanella Netto
2023-01-11 21:11 ` Carlos O'Donell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220930192613.3491147-10-adhemerval.zanella@linaro.org \
--to=adhemerval.zanella@linaro.org \
--cc=brauner@kernel.org \
--cc=libc-alpha@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).