From: Arnd Bergmann <arnd@kernel.org>
To: "Maciej W. Rozycki" <macro@orcam.me.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Heiner Kallweit <hkallweit1@gmail.com>,
Nikolai Zhubr <zhubr.2@gmail.com>,
netdev <netdev@vger.kernel.org>, Jeff Garzik <jgarzik@pobox.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Realtek 8139 problem on 486.
Date: Mon, 21 Jun 2021 17:20:59 +0200 [thread overview]
Message-ID: <CAK8P3a30Pz+_Mud-VYsMw9XEsE5KBUHyMF4KzUr9XYiXi9D91g@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2106211623090.779@angie.orcam.me.uk>
On Mon, Jun 21, 2021 at 4:42 PM Maciej W. Rozycki <macro@orcam.me.uk> wrote:
>
> On Mon, 21 Jun 2021, Arnd Bergmann wrote:
>
> > I also found an slightly more recent discussion, from where it seems
> > that the authoritative decision when it came up in the past was that edge
> > triggered interrupts are supposed to work as long as they are not
> > shared [3][4].
>
> Sadly Linus's rule applies both ways: if a device has been designed with
> level-triggered interrupts in mind, there may be no race-free way to
> ensure an active-to-inactive-to-active transition has happened on its IRQ
> line as the driver acknowledges handling in the relevant device's CSR.
>
> The rule of thumb is to acknowledge early in the handler, and to work
> around broken configurations it may be desirable to also briefly mask all
> the interrupt sources with the device so as to make sure it deasserts its
> IRQ line even if another interrupt has already been queued. OTOH if IRQ
> sharing is to be supported a device absolutely has to have an interrupt
> mask register, as the system cannot rely on masking at the interrupt
> controller if multiple devices are to be handled with a single line. I
> suspect many of our drivers do not do such precautionary masking though.
>
> Is there a mask register with the 8139?
Ah, it seems that the Cc list got dropped in a different sub-thread, see
https://pastebin.com/3FUUrg7C for a version of my patch that Nikolai
tested successfully. This one goes further by completely masking
all interrupts between the hardirq handler and the subsequent
napi_complete_done(). This may not be the most efficient way of
doing it, but it seems good enough according to his measurements,
and it is a relatively safe and straightforward change.
Arnd
next prev parent reply other threads:[~2021-06-21 15:23 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-29 14:08 Realtek 8139 problem on 486 Nikolai Zhubr
2021-05-29 18:42 ` Heiner Kallweit
2021-05-29 21:44 ` tedheadster
2021-05-30 0:49 ` Nikolai Zhubr
2021-05-30 10:36 ` Nikolai Zhubr
2021-05-30 17:27 ` Nikolai Zhubr
2021-05-30 20:54 ` Arnd Bergmann
2021-05-30 23:17 ` Nikolai Zhubr
2021-05-31 16:53 ` Nikolai Zhubr
2021-05-31 18:39 ` Arnd Bergmann
2021-05-31 22:18 ` Nikolai Zhubr
2021-05-31 22:30 ` Heiner Kallweit
2021-06-01 7:20 ` Arnd Bergmann
2021-06-01 10:53 ` Nikolai Zhubr
2021-06-01 11:42 ` Heiner Kallweit
2021-06-01 16:09 ` Nikolai Zhubr
2021-06-01 21:48 ` Heiner Kallweit
2021-06-01 23:37 ` Nikolai Zhubr
2021-06-02 9:12 ` Arnd Bergmann
2021-06-07 23:07 ` Nikolai Zhubr
2021-06-08 7:44 ` Arnd Bergmann
2021-06-08 20:32 ` Nikolai Zhubr
2021-06-08 20:45 ` Arnd Bergmann
2021-06-08 22:07 ` Nikolai Zhubr
2021-06-09 7:09 ` Arnd Bergmann
2021-06-12 17:40 ` Nikolai Zhubr
2021-06-12 22:41 ` Arnd Bergmann
2021-06-13 14:10 ` Nikolai Zhubr
2021-06-13 21:52 ` Arnd Bergmann
2021-06-03 18:32 ` Maciej W. Rozycki
2021-06-04 7:36 ` Arnd Bergmann
2021-06-20 0:34 ` Thomas Gleixner
2021-06-20 10:19 ` Arnd Bergmann
2021-06-21 4:10 ` Maciej W. Rozycki
2021-06-21 11:22 ` Arnd Bergmann
2021-06-21 14:42 ` Maciej W. Rozycki
2021-06-21 15:20 ` Arnd Bergmann [this message]
2021-06-22 11:12 ` David Laight
2021-06-22 12:42 ` Nikolai Zhubr
2021-06-22 13:22 ` Arnd Bergmann
2021-06-22 18:42 ` Nikolai Zhubr
2021-06-22 19:26 ` Arnd Bergmann
2021-06-23 1:04 ` Maciej W. Rozycki
2021-06-24 17:56 ` Nikolai Zhubr
2021-06-24 18:25 ` Maciej W. Rozycki
2021-07-14 23:32 ` Maciej W. Rozycki
2021-07-15 7:32 ` Nikolai Zhubr
2021-07-16 23:48 ` Maciej W. Rozycki
2021-06-23 16:31 ` Nikolai Zhubr
2021-06-23 23:39 ` Maciej W. Rozycki
2021-06-24 8:28 ` Arnd Bergmann
2021-07-02 19:02 ` Nikolai Zhubr
2021-07-03 9:10 ` Arnd Bergmann
2021-07-08 19:21 ` Nikolai Zhubr
2021-07-09 7:31 ` Arnd Bergmann
2021-07-09 12:43 ` David Laight
2021-06-01 17:44 ` Maciej W. Rozycki
2021-06-02 15:14 ` Nikolai Zhubr
2021-06-02 15:28 ` Arnd Bergmann
2021-05-31 19:05 ` Heiner Kallweit
2021-05-31 18:29 ` Denis Kirjanov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAK8P3a30Pz+_Mud-VYsMw9XEsE5KBUHyMF4KzUr9XYiXi9D91g@mail.gmail.com \
--to=arnd@kernel.org \
--cc=bp@alien8.de \
--cc=hkallweit1@gmail.com \
--cc=hpa@zytor.com \
--cc=jgarzik@pobox.com \
--cc=macro@orcam.me.uk \
--cc=mingo@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=zhubr.2@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.