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Commit b087498e authored by Ulrich Drepper's avatar Ulrich Drepper Committed by Linus Torvalds
Browse files

flag parameters: eventfd 



This patch adds the new eventfd2 syscall.  It extends the old eventfd
syscall by one parameter which is meant to hold a flag value.  In this
patch the only flag support is EFD_CLOEXEC which causes the close-on-exec
flag for the returned file descriptor to be set.

A new name EFD_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 <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_eventfd2
# ifdef __x86_64__
#  define __NR_eventfd2 290
# elif defined __i386__
#  define __NR_eventfd2 328
# else
#  error "need __NR_eventfd2"
# endif
#endif

#define EFD_CLOEXEC O_CLOEXEC

int
main (void)
{
  int fd = syscall (__NR_eventfd2, 1, 0);
  if (fd == -1)
    {
      puts ("eventfd2(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("eventfd2(0) sets close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_eventfd2, 1, EFD_CLOEXEC);
  if (fd == -1)
    {
      puts ("eventfd2(EFD_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("eventfd2(EFD_CLOEXEC) does not set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

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

[akpm@linux-foundation.org: add sys_ni stub]
Signed-off-by: default avatarUlrich Drepper <drepper@redhat.com>
Acked-by: default avatarDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9deb27ba

arch/x86/ia32/ia32entry.S

+1 −0
Original line number Diff line number Diff line
@@ -827,4 +827,5 @@ ia32_sys_call_table: 
	.quad compat_sys_timerfd_settime	/* 325 */

	.quad compat_sys_timerfd_gettime

	.quad compat_sys_signalfd4

	.quad sys_eventfd2

ia32_syscall_end:

arch/x86/kernel/syscall_table_32.S

+1 −0
Original line number Diff line number Diff line
@@ -327,3 +327,4 @@ ENTRY(sys_call_table) 
	.long sys_timerfd_settime	/* 325 */

	.long sys_timerfd_gettime

	.long sys_signalfd4

	.long sys_eventfd2

fs/eventfd.c

+11 −2
Original line number Diff line number Diff line
@@ -198,11 +198,14 @@ struct file *eventfd_fget(int fd) 
	return file;

}



asmlinkage long sys_eventfd(unsigned int count)

asmlinkage long sys_eventfd2(unsigned int count, int flags)

{

	int fd;

	struct eventfd_ctx *ctx;



	if (flags & ~EFD_CLOEXEC)

		return -EINVAL;



	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);

	if (!ctx)

		return -ENOMEM;
@@ -214,9 +217,15 @@ asmlinkage long sys_eventfd(unsigned int count) 
	 * When we call this, the initialization must be complete, since

	 * anon_inode_getfd() will install the fd.

	 */

	fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx, 0);

	fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx,

			      flags & O_CLOEXEC);

	if (fd < 0)

		kfree(ctx);

	return fd;

}



asmlinkage long sys_eventfd(unsigned int count)

{

	return sys_eventfd2(count, 0);

}

include/asm-x86/unistd_32.h

+1 −0
Original line number Diff line number Diff line
@@ -333,6 +333,7 @@ 
#define __NR_timerfd_settime	325

#define __NR_timerfd_gettime	326

#define __NR_signalfd4		327

#define __NR_eventfd2		328



#ifdef __KERNEL__

include/asm-x86/unistd_64.h

+2 −0
Original line number Diff line number Diff line
@@ -643,6 +643,8 @@ __SYSCALL(__NR_timerfd_gettime, sys_timerfd_gettime) 
__SYSCALL(__NR_paccept, sys_paccept)

#define __NR_signalfd4				289

__SYSCALL(__NR_signalfd4, sys_signalfd4)

#define __NR_eventfd2				290

__SYSCALL(__NR_eventfd2, sys_eventfd2)





#ifndef __NO_STUBS