On Tue, Jan 31, 2017 at 10:14 AM, Mateusz Guzik [off-list ref] wrote:

On Mon, Jan 30, 2017 at 10:44:03PM -0800, Cong Wang wrote:

quoted

Mind being more specific?

Consider 2 threads which bind the same socket, but with different paths.

Currently exactly one file will get created, the one used to bind.

With your patch both threads can succeed creating their respective
files, but only one will manage to bind. The other one must error out,
but it already created a file it is unclear what to do with.

In this case, it simply puts the path back:

        err = -EINVAL;
        if (u->addr)
                goto out_up;
[...]

out_up:
        mutex_unlock(&u->bindlock);
out_put:
        if (err)
                path_put(&path);
out:
        return err;


Which is what unix_release_sock() does too:

        if (path.dentry)
                path_put(&path);