Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210416192413.1514419-1-eric.dumazet@gmail.com>
 <CAHk-=wjbvzCAhAtvG0d81W5o0-KT5PPTHhfJ5ieDFq+bGtgOYg@mail.gmail.com>
 <CAHk-=wgdyusj4Sz6zVOGvD8pNiYmPik3t4-o0TXB9cTUgz_0uw@mail.gmail.com>
 <CAHk-=wjYVZZpqDGH2Q=kMOyOqBhpbt8t8JdEWZHDGrPiV=_ifA@mail.gmail.com>
 <YHskaCSFOE1AYyoP@zeniv-ca.linux.org.uk> <YHtFciNvBWYJ0ku2@zeniv-ca.linux.org.uk>
 <YHtGhqBXhWlUHHRm@zeniv-ca.linux.org.uk>
In-Reply-To: <YHtGhqBXhWlUHHRm@zeniv-ca.linux.org.uk>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sat, 17 Apr 2021 15:11:49 -0700
Message-ID: <CAHk-=wi+8sz1kjpVnZ_MNbX0YNzGBXTTu4UyiR+1RWrFdbJ7Hw@mail.gmail.com>
Subject: Re: [PATCH] x86/uaccess: small optimization in unsafe_copy_to_user()
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Eric Dumazet <eric.dumazet@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        "Theodore Ts'o" <tytso@mit.edu>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Sat, Apr 17, 2021 at 1:35 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> No, wait - we have non-NULL buf->prev_reclen, so we'll hit
> with buf->error completely ignored.  Nevermind.

Yeah, I'm pretty sure I even tested that -EINTR case at one point.

Of course, it could easily have gotten broken again, so that's not a
strong argument.

That said, the "buf->err" handling has always been very confusing, and
it would be lovely to get rid of that confusion.

I don't remember why we did it that way, but I think it's because
low-level filesystems ended up changing the error that the filldir()
function returned or something like that.

         Linus