linux-kernel - Re: [PATCH v2] firmware: fix sending -ERESTARTSYS due to signal on fallback

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Message-ID: <20170607171507.GL27288@wotan.suse.de>
Date:   Wed, 7 Jun 2017 19:15:07 +0200
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Alan Cox <alan@...ux.intel.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Theodore Ts'o <tytso@....edu>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Stephen Boyd <stephen.boyd@...aro.org>,
        "Li, Yi" <yi1.li@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jonathan Corbet <corbet@....net>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        "Fuzzey, Martin" <mfuzzey@...keon.com>,
        Linux API <linux-api@...r.kernel.org>,
        Daniel Wagner <wagi@...om.org>,
        David Woodhouse <dwmw2@...radead.org>,
        jewalt@...innovations.com, rafal@...ecki.pl,
        Arend Van Spriel <arend.vanspriel@...adcom.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Moritz Fischer <moritz.fischer@...us.com>,
        Petr Mladek <pmladek@...e.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        David Howells <dhowells@...hat.com>,
        Peter Jones <pjones@...hat.com>,
        Hans de G oede <hdegoede@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] firmware: fix sending -ERESTARTSYS due to signal on
 fallback

On Wed, Jun 07, 2017 at 01:25:51PM +0100, Alan Cox wrote:
> > What's wrong with saying that the only way to interrupt firmware
> > loading is to kill the process? So ctrl-c will no longer interrupt
> > it, but I do not think that ease of aborting firmware update is
> > primary goal here. I consider simple is good here.
> 
> Agreed 100%. The user process did not ask for firmware load, it asked
> for an I/O operation. Semantically it should appear as if someone else
> did the firmware load and it just had to wait for it to happen.

Fine by me ! Will wrap up the patch for the new killable swait then.
I suppose noting it as a stable fix is worth it given the known issues
with for example Android killing loaders unexpectedly.

Unless I hear otherwise I'll also provide a follow up to return -EINTR instead
of -EAGAIN if swait returned -ERESTARTSYS, this way at least userspace could
tell a signal was definitely received. I *don't* think that follow up is
required for stable though.

  Luis