From: Joseph Myers <joseph@codesourcery.com>
To: <libc-alpha@sourceware.org>
Subject: Simplify sendmmsg code
Date: Tue, 09 May 2017 15:54:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.20.1705091552540.16186@digraph.polyomino.org.uk> (raw)
Now we can assume a kernel with sendmmsg support, this patch
simplifies the implementation to be similar to that for accept4:
either using socketcall or the syscall according to whether the
syscall is known to be available, without further fallback
implementations. The __ASSUME_SENDMMSG macro is kept (now defined
unconditionally), since it's used in resolv/res_send.c.
Tested for x86_64 and x86.
2017-05-09 Joseph Myers <joseph@codesourcery.com>
* sysdeps/unix/sysv/linux/kernel-features.h
(__ASSUME_SENDMMSG_SYSCALL): Define unconditionally.
(__ASSUME_SENDMMSG): Likewise.
(__ASSUME_SENDMMSG_SOCKETCALL): Remove macro.
* sysdeps/unix/sysv/linux/sendmmsg.c (__sendmmsg): Define using
sendmmsg syscall if that can be assumed to be present, socketcall
otherwise, with no fallback for runtime failure.
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 74ac627..c9212b4 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -105,13 +105,8 @@
/* Support for sendmmsg functionality was added in 3.0. The macros
defined correspond to those for accept4 and recvmmsg. */
-#if __LINUX_KERNEL_VERSION >= 0x030000
-# ifdef __ASSUME_SOCKETCALL
-# define __ASSUME_SENDMMSG_SOCKETCALL 1
-# endif
-# define __ASSUME_SENDMMSG_SYSCALL 1
-# define __ASSUME_SENDMMSG 1
-#endif
+#define __ASSUME_SENDMMSG_SYSCALL 1
+#define __ASSUME_SENDMMSG 1
/* On most architectures, most socket syscalls are supported for all
supported kernel versions, but on some socketcall architectures
diff --git a/sysdeps/unix/sysv/linux/sendmmsg.c b/sysdeps/unix/sysv/linux/sendmmsg.c
index 2dd0eba..c559623 100644
--- a/sysdeps/unix/sysv/linux/sendmmsg.c
+++ b/sysdeps/unix/sysv/linux/sendmmsg.c
@@ -21,73 +21,22 @@
#include <sysdep-cancel.h>
#include <sys/syscall.h>
+#include <socketcall.h>
#include <kernel-features.h>
-/* Do not use the sendmmsg syscall on socketcall architectures unless
- it was added at the same time as the socketcall support or can be
- assumed to be present. */
-#if defined __ASSUME_SOCKETCALL \
- && !defined __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL \
- && !defined __ASSUME_SENDMMSG_SYSCALL
-# undef __NR_sendmmsg
-#endif
-
-#ifdef __NR_sendmmsg
-int
-__sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
-{
- return SYSCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
-}
-libc_hidden_def (__sendmmsg)
-weak_alias (__sendmmsg, sendmmsg)
-#elif defined __NR_socketcall
-# include <socketcall.h>
-# ifdef __ASSUME_SENDMMSG_SOCKETCALL
int
__sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
{
+ /* Do not use the sendmmsg syscall on socketcall architectures unless
+ it was added at the same time as the socketcall support or can be
+ assumed to be present. */
+#if defined __ASSUME_SOCKETCALL \
+ && !defined __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL \
+ && !defined __ASSUME_SENDMMSG_SYSCALL
return SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
+#else
+ return SYSCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
+#endif
}
-# else
-static int have_sendmmsg;
-
-int
-__sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
-{
- if (__glibc_likely (have_sendmmsg >= 0))
- {
- int ret = SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
- /* The kernel returns -EINVAL for unknown socket operations.
- We need to convert that error to an ENOSYS error. */
- if (__builtin_expect (ret < 0, 0)
- && have_sendmmsg == 0
- && errno == EINVAL)
- {
- /* Try another call, this time with an invalid file
- descriptor and all other parameters cleared. This call
- will not cause any harm and it will return
- immediately. */
- ret = SOCKETCALL_CANCEL (invalid, -1);
- if (errno == EINVAL)
- {
- have_sendmmsg = -1;
- __set_errno (ENOSYS);
- }
- else
- {
- have_sendmmsg = 1;
- __set_errno (EINVAL);
- }
- return -1;
- }
- return ret;
- }
- __set_errno (ENOSYS);
- return -1;
-}
-# endif /* __ASSUME_SENDMMSG_SOCKETCALL */
libc_hidden_def (__sendmmsg)
weak_alias (__sendmmsg, sendmmsg)
-#else
-# include <socket/sendmmsg.c>
-#endif
--
Joseph S. Myers
joseph@codesourcery.com
next reply other threads:[~2017-05-09 15:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-09 15:54 Joseph Myers [this message]
2017-05-09 18:41 ` Adhemerval Zanella
2017-05-09 20:28 ` Florian Weimer
2017-05-09 20:58 ` Adhemerval Zanella
2017-05-10 7:41 ` Florian Weimer
2017-05-10 12:14 ` Adhemerval Zanella
2017-05-12 9:17 ` Florian Weimer
2017-05-12 13:52 ` Adhemerval Zanella
2017-05-12 14:12 ` Joseph Myers
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