flag parameters: NONBLOCK in eventfd

Ulrich Drepper · torvalds · commit e7d476dfdf0b · 2008-07-24T10:47:29.000-07:00
This patch adds support for the EFD_NONBLOCK flag to eventfd2.  The
additional changes needed are minimal.

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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include &lt;fcntl.h&gt;
#include &lt;stdio.h&gt;
#include &lt;unistd.h&gt;
#include &lt;sys/syscall.h&gt;

#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_NONBLOCK O_NONBLOCK

int
main (void)
{
  int fd = syscall (__NR_eventfd2, 1, 0);
  if (fd == -1)
    {
      puts ("eventfd2(0) failed");
      return 1;
    }
  int fl = fcntl (fd, F_GETFL);
  if (fl == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (fl &amp; O_NONBLOCK)
    {
      puts ("eventfd2(0) sets non-blocking mode");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_eventfd2, 1, EFD_NONBLOCK);
  if (fd == -1)
    {
      puts ("eventfd2(EFD_NONBLOCK) failed");
      return 1;
    }
  fl = fcntl (fd, F_GETFL);
  if (fl == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((fl &amp; O_NONBLOCK) == 0)
    {
      puts ("eventfd2(EFD_NONBLOCK) does not set non-blocking mode");
      return 1;
    }
  close (fd);

  puts ("OK");

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

Signed-off-by: Ulrich Drepper &lt;drepper@redhat.com&gt;
Acked-by: Davide Libenzi &lt;davidel@xmailserver.org&gt;
Cc: Michael Kerrisk &lt;mtk.manpages@googlemail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/fs/eventfd.c b/fs/eventfd.c
@@ -203,7 +203,7 @@ asmlinkage long sys_eventfd2(unsigned int count, int flags)
 	int fd;
 	struct eventfd_ctx *ctx;
 
-	if (flags & ~EFD_CLOEXEC)
+	if (flags & ~(EFD_CLOEXEC | EFD_NONBLOCK))
 		return -EINVAL;
 
 	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
@@ -218,7 +218,7 @@ asmlinkage long sys_eventfd2(unsigned int count, int flags)
 	 * anon_inode_getfd() will install the fd.
 	 */
 	fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx,
-			      flags & O_CLOEXEC);
+			      flags & (O_CLOEXEC | O_NONBLOCK));
 	if (fd < 0)
 		kfree(ctx);
 	return fd;
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
@@ -10,11 +10,12 @@
 
 #ifdef CONFIG_EVENTFD
 
-/* For O_CLOEXEC */
+/* For O_CLOEXEC and O_NONBLOCK */
 #include <linux/fcntl.h>
 
 /* Flags for eventfd2.  */
 #define EFD_CLOEXEC O_CLOEXEC
+#define EFD_NONBLOCK O_NONBLOCK
 
 struct file *eventfd_fget(int fd);
 int eventfd_signal(struct file *file, int n);
