flag parameters: epoll_create

This patch adds the new epoll_create2 syscall.  It extends the old epoll_create
syscall by one parameter which is meant to hold a flag value.  In this
patch the only flag support is EPOLL_CLOEXEC which causes the close-on-exec
flag for the returned file descriptor to be set.

A new name EPOLL_CLOEXEC is introduced which in this implementation must
have the same value as O_CLOEXEC.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <fcntl.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_epoll_create2
# ifdef __x86_64__
#  define __NR_epoll_create2 291
# elif defined __i386__
#  define __NR_epoll_create2 329
# else
#  error "need __NR_epoll_create2"
# endif
#endif

#define EPOLL_CLOEXEC O_CLOEXEC

int
main (void)
{
  int fd = syscall (__NR_epoll_create2, 1, 0);
  if (fd == -1)
    {
      puts ("epoll_create2(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("epoll_create2(0) set close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_epoll_create2, 1, EPOLL_CLOEXEC);
  if (fd == -1)
    {
      puts ("epoll_create2(EPOLL_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("epoll_create2(EPOLL_CLOEXEC) set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 8 insertions, 0 deletions

diff --git a/include/asm-x86/unistd_32.h b/include/asm-x86/unistd_32.h
index edbd8723c939..a37d6b0c4e1e 100644
--- a/include/asm-x86/unistd_32.h
+++ b/include/asm-x86/unistd_32.h
@@ -334,6 +334,7 @@
 #define __NR_timerfd_gettime    326
 #define __NR_signalfd4          327
 #define __NR_eventfd2           328
+#define __NR_epoll_create2      329
 
 #ifdef __KERNEL__
 
diff --git a/include/asm-x86/unistd_64.h b/include/asm-x86/unistd_64.h
index fb059a6feeb1..a1a4a5b6e5ee 100644
--- a/include/asm-x86/unistd_64.h
+++ b/include/asm-x86/unistd_64.h
@@ -645,6 +645,8 @@ __SYSCALL(__NR_paccept, sys_paccept)
 __SYSCALL(__NR_signalfd4, sys_signalfd4)
 #define __NR_eventfd2                           290
 __SYSCALL(__NR_eventfd2, sys_eventfd2)
+#define __NR_epoll_create2                      291
+__SYSCALL(__NR_epoll_create2, sys_epoll_create2)
 
 
 #ifndef __NO_STUBS
diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index cf79853967ff..1cfaa40059c8 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -14,8 +14,12 @@
 #ifndef _LINUX_EVENTPOLL_H
 #define _LINUX_EVENTPOLL_H
 
+/* For O_CLOEXEC */
+#include <linux/fcntl.h>
 #include <linux/types.h>
 
+/* Flags for epoll_create2.  */
+#define EPOLL_CLOEXEC O_CLOEXEC
 
 /* Valid opcodes to issue to sys_epoll_ctl() */
 #define EPOLL_CTL_ADD 1
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 9ab09926a7f2..85953240f28c 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -430,6 +430,7 @@ asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
                         fd_set __user *exp, struct timeval __user *tvp);
 asmlinkage long sys_epoll_create(int size);
+asmlinkage long sys_epoll_create2(int size, int flags);
 asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,
                                 struct epoll_event __user *event);
 asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,