linux-kernel - Re: Pending splice(file -> FIFO) excludes all other FIFO operations forever (was: ... always blocks read(FIFO), regardless of O

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Date:   Fri, 7 Jul 2023 17:07:09 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Ahelenia Ziemiańska 
        <nabijaczleweli@...ijaczleweli.xyz>,
        Christian Brauner <brauner@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        David Howells <dhowells@...hat.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Pending splice(file -> FIFO) excludes all other FIFO operations
 forever (was: ... always blocks read(FIFO), regardless of O_NONBLOCK on read side?)

On Fri, 7 Jul 2023 at 17:00, Matthew Wilcox <willy@...radead.org> wrote:
>
> Do we really want interruptible here rather than killable?

Yes, we actually do need to be just regular interruptible,

This is a bog-standard "IO to/from pipe" situation, which is interruptible.

> That is, do we want SIGWINCH or SIGALRM to result in a short read?

Now, that's a different issue, and is actually handled by the signal
layer: a signal that is ignored (where "ignored" includes the case of
"default handler") will be dropped early, exactly because we don't
want to interrupt things like tty or pipe reads when you resize the
window.

Of course, if you actually *catch* SIGWINCH, then you will get that
short read on a window change.

           Linus