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Subject[PATCH 15/18] flag parameters: NONBLOCK in eventfd
This patch adds support for the EFD_NONBLOCK flag to eventfd2.  The
additional changes needed are minimal thanks to the previous preparation.

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_NONBLOCK (1 << 1)

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 & 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 & O_NONBLOCK) == 0)
{
puts ("eventfd2(EFD_NONBLOCK) does not set non-blocking mode");
return 1;
}
close (fd);

puts ("OK");

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

fs/eventfd.c | 1 +
include/linux/eventfd.h | 1 +
2 files changed, 2 insertions(+)


Signed-off-by: Ulrich Drepper <drepper@redhat.com>

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 343942d..ddb543d 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -201,6 +201,7 @@ struct file *eventfd_fget(int fd)

static const struct flags_rmap eventfd_file_flags_remap[] = {
{ EFD_CLOEXEC, O_CLOEXEC },
+ { EFD_NONBLOCK, O_NONBLOCK }
};

asmlinkage long sys_eventfd2(unsigned int count, int flags)
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index a701399..0c2f68b 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -12,6 +12,7 @@

/* Flags for eventfd2. */
#define EFD_CLOEXEC (1 << 0)
+#define EFD_NONBLOCK (1 << 1)

struct file *eventfd_fget(int fd);
int eventfd_signal(struct file *file, int n);

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