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Simplify sendmmsg code.

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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.

	* 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.
This commit is contained in:
Joseph Myers 2017-05-09 20:01:52 +00:00
parent 9a45f54310
commit 0cb5da5c09
3 changed files with 20 additions and 68 deletions
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8
ChangeLog
View File

@ -1,5 +1,13 @@
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.
* sysdeps/unix/sysv/linux/kernel-features.h
(__ASSUME_RECVMMSG_SYSCALL): Define unconditionally.
(__ASSUME_RECVMMSG_SOCKETCALL): Remove macro.

9
sysdeps/unix/sysv/linux/kernel-features.h
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@ -99,13 +99,8 @@
/* 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

71
sysdeps/unix/sysv/linux/sendmmsg.c
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@ -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. */
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
# 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)
{
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