Re: [PATCH 13/18] io_uring: add file set registration

On 2/7/19 9:30 AM, Al Viro wrote:

On Thu, Feb 07, 2019 at 09:14:41AM -0700, Jens Axboe wrote:

quoted

I created a small app to do just that, and ran it and verified that
->release() is called and the io_uring is released as expected. This
is run on the current -git branch, which has a socket backing for
the io_uring fd itself, but not for the registered files.

What am I missing here? Attaching the program as a reference.

quoted

int main(int argc, char *argv[])
{
	int sp[2], pid, ring_fd, ret;

	if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sp) != 0) {
		perror("Failed to create Unix-domain socket pair\n");
		return 1;
	}

	ring_fd = get_ring_fd();
	if (ring_fd < 0)
		return 1;

	ret = io_uring_register_files(ring_fd, sp[0], sp[1]);
	if (ret < 0) {
		perror("register files");
		return 1;
	}

	pid = fork();
	if (pid) {
		printf("Sending fd %d\n", ring_fd);

		send_fd(sp[0], ring_fd);
	} else {
		int fd;

		fd = recv_fd(sp[1]);

Well, yes - once you receive it, you obviously have no references
sitting in SCM_RIGHTS anymore.

Get rid of recv_fd() there (along with fork(), while we are at it - what's
it for?) and just do send_fd + these 3 close (or just exit, for that matter).

Ah got it, yes you are right, that does leak.

Thanks for the other (very) detailed note, I'll add a socket backing for the
registered files. I'll respond to the other details in there a bit later.

-- 
Jens Axboe