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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: 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>
master
Ulrich Drepper 14 years ago
committed by Linus Torvalds
parent
commit
b087498eb5
  1. 1
      arch/x86/ia32/ia32entry.S
  2. 1
      arch/x86/kernel/syscall_table_32.S
  3. 13
      fs/eventfd.c
  4. 1
      include/asm-x86/unistd_32.h
  5. 2
      include/asm-x86/unistd_64.h
  6. 6
      include/linux/eventfd.h
  7. 1
      include/linux/syscalls.h
  8. 1
      kernel/sys_ni.c

1
arch/x86/ia32/ia32entry.S

@ -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:

1
arch/x86/kernel/syscall_table_32.S

@ -327,3 +327,4 @@ ENTRY(sys_call_table)
.long sys_timerfd_settime /* 325 */
.long sys_timerfd_gettime
.long sys_signalfd4
.long sys_eventfd2

13
fs/eventfd.c

@ -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);
}

1
include/asm-x86/unistd_32.h

@ -333,6 +333,7 @@
#define __NR_timerfd_settime 325
#define __NR_timerfd_gettime 326
#define __NR_signalfd4 327
#define __NR_eventfd2 328
#ifdef __KERNEL__

2
include/asm-x86/unistd_64.h

@ -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

6
include/linux/eventfd.h

@ -10,6 +10,12 @@
#ifdef CONFIG_EVENTFD
/* For O_CLOEXEC */
#include <linux/fcntl.h>
/* Flags for eventfd2. */
#define EFD_CLOEXEC O_CLOEXEC
struct file *eventfd_fget(int fd);
int eventfd_signal(struct file *file, int n);

1
include/linux/syscalls.h

@ -617,6 +617,7 @@ asmlinkage long sys_timerfd_settime(int ufd, int flags,
struct itimerspec __user *otmr);
asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
asmlinkage long sys_eventfd(unsigned int count);
asmlinkage long sys_eventfd2(unsigned int count, int flags);
asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
int kernel_execve(const char *filename, char *const argv[], char *const envp[]);

1
kernel/sys_ni.c

@ -164,3 +164,4 @@ cond_syscall(sys_timerfd_gettime);
cond_syscall(compat_sys_timerfd_settime);
cond_syscall(compat_sys_timerfd_gettime);
cond_syscall(sys_eventfd);
cond_syscall(sys_eventfd2);

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