Assume that accept4 is always available and works

Simplify the Linux accept4 implementation based on the assumption
that it is available in some way.  __ASSUME_ACCEPT4_SOCKETCALL was
previously unused, so remove it.

For ia64, the accept4 system call (and socket call) were backported
in kernel version 3.2.18.  Reflect this in the installation
instructions.

7 files changed, 18 insertions, 83 deletions

diff --git a/sysdeps/mach/hurd/kernel-features.h b/sysdeps/mach/hurd/kernel-features.h
index 20cb3ba..1966388 100644
--- a/sysdeps/mach/hurd/kernel-features.h
+++ b/sysdeps/mach/hurd/kernel-features.h
@@ -19,5 +19,3 @@
 /* This file can define __ASSUME_* macros checked by certain source files.
    Almost none of these are used outside of sysdeps/unix/sysv/linux code.
    But those referring to POSIX-level features like O_* flags can be.  */
-
-#define __ASSUME_ACCEPT4	1
diff --git a/sysdeps/nacl/kernel-features.h b/sysdeps/nacl/kernel-features.h
index 32834fd..ba315b6 100644
--- a/sysdeps/nacl/kernel-features.h
+++ b/sysdeps/nacl/kernel-features.h
@@ -19,7 +19,3 @@
 /* This file can define __ASSUME_* macros checked by certain source files.
    Almost none of these are used outside of sysdeps/unix/sysv/linux code.
    But those referring to POSIX-level features like O_* flags can be.  */
-
-/*
-#define __ASSUME_ACCEPT4	1
-*/
diff --git a/sysdeps/unix/sysv/linux/accept4.c b/sysdeps/unix/sysv/linux/accept4.c
index 53afd7a..0592f43 100644
--- a/sysdeps/unix/sysv/linux/accept4.c
+++ b/sysdeps/unix/sysv/linux/accept4.c
@@ -22,75 +22,20 @@
 
 #include <sysdep-cancel.h>
 #include <sys/syscall.h>
+#include <socketcall.h>
 #include <kernel-features.h>
 
+int
+accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
+{
 /* Do not use the accept4 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_ACCEPT4_SYSCALL_WITH_SOCKETCALL \
     && !defined __ASSUME_ACCEPT4_SYSCALL
-# undef __NR_accept4
-#endif
-
-#ifdef __NR_accept4
-int
-accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
-{
-  return SYSCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
-}
-#elif defined __NR_socketcall
-# include <socketcall.h>
-# ifdef __ASSUME_ACCEPT4_SOCKETCALL
-int
-accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
-{
   return SOCKETCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
-}
-# else
-static int have_accept4;
-
-int
-accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
-{
-  if (__glibc_likely (have_accept4 >= 0))
-    {
-      int ret = SOCKETCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len,
-				   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_accept4 == 0
-	  && errno == EINVAL)
-	{
-	  /* Try another call, this time with the FLAGS parameter
-	     cleared and an invalid file descriptor.  This call will not
-	     cause any harm and it will return immediately.  */
-	  ret = SOCKETCALL_CANCEL (invalid, -1);
-	  if (errno == EINVAL)
-	    {
-	      have_accept4 = -1;
-	      __set_errno (ENOSYS);
-	    }
-	  else
-	    {
-	      have_accept4 = 1;
-	      __set_errno (EINVAL);
-	    }
-	  return -1;
-	}
-      return ret;
-    }
-  __set_errno (ENOSYS);
-  return -1;
-}
-# endif /* __ASSUME_ACCEPT4_SOCKETCALL  */
-#else /* __NR_socketcall   */
-int
-accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
-{
-  __set_errno (ENOSYS);
-  return -1;
-}
-stub_warning (accept4)
+#else
+  return SYSCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
 #endif
+}
diff --git a/sysdeps/unix/sysv/linux/ia64/configure b/sysdeps/unix/sysv/linux/ia64/configure
index 1d4e5d1..3cf7237 100644
--- a/sysdeps/unix/sysv/linux/ia64/configure
+++ b/sysdeps/unix/sysv/linux/ia64/configure
@@ -2,3 +2,7 @@
  # Local configure fragment for sysdeps/unix/sysv/linux/ia64
 
 ldd_rewrite_script=$dir/ldd-rewrite.sed
+
+# First version with support for the accept4 system call.
+# Linux 3.3 includes it as well.
+arch_minimum_kernel=3.2.18
diff --git a/sysdeps/unix/sysv/linux/ia64/configure.ac b/sysdeps/unix/sysv/linux/ia64/configure.ac
index 4fb5647..94a578c 100644
--- a/sysdeps/unix/sysv/linux/ia64/configure.ac
+++ b/sysdeps/unix/sysv/linux/ia64/configure.ac
@@ -2,3 +2,7 @@ GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
 # Local configure fragment for sysdeps/unix/sysv/linux/ia64
 
 ldd_rewrite_script=$dir/ldd-rewrite.sed
+
+# First version with support for the accept4 system call.
+# Linux 3.3 includes it as well.
+arch_minimum_kernel=3.2.18
diff --git a/sysdeps/unix/sysv/linux/ia64/kernel-features.h b/sysdeps/unix/sysv/linux/ia64/kernel-features.h
index ac9403e..cda0ad6 100644
--- a/sysdeps/unix/sysv/linux/ia64/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/ia64/kernel-features.h
@@ -22,13 +22,8 @@
 
 #include_next <kernel-features.h>
 
-/* Support for the accept4 syscall was added in 3.3.  */
-#if __LINUX_KERNEL_VERSION < 0x030300
-# undef __ASSUME_ACCEPT4_SYSCALL
-# undef __ASSUME_ACCEPT4
-#endif
-
 #define __ASSUME_RECV_SYSCALL   	1
 #define __ASSUME_SEND_SYSCALL		1
+#define __ASSUME_ACCEPT4_SYSCALL	1
 
 #endif /* _KERNEL_FEATURES_H */
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index fd936c5..b981466 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -75,18 +75,11 @@
    architectures using a separate syscall rather than socketcall that
    syscall was only added later, and some architectures first had
    socketcall support then a separate syscall.  Define
-   __ASSUME_ACCEPT4_SOCKETCALL if glibc uses socketcall on this
-   architecture and accept4 is available through socketcall,
    __ASSUME_ACCEPT4_SYSCALL if it is available through a separate
-   syscall, __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL if it became
+   syscall, and __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL if it became
    available through a separate syscall at the same time as through
-   socketcall, and __ASSUME_ACCEPT4 if the accept4 function is known
-   to work.  */
-#ifdef __ASSUME_SOCKETCALL
-# define __ASSUME_ACCEPT4_SOCKETCALL	1
-#endif
+   socketcall.  */
 #define __ASSUME_ACCEPT4_SYSCALL	1
-#define __ASSUME_ACCEPT4	1
 
 /* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29.  */
 #define __ASSUME_FUTEX_CLOCK_REALTIME	1