[uml-devel] Networking issues with 2.6.29

[uml-devel] Networking issues with 2.6.29

[Yehuda Sadeh Weinraub]

Network doesn't seem to work for me in 2.6.29, although it was working
in 2.6.28. System behavior seemed really strange, as it sometimes did
work when I was using the same uml machine, when using a different
user. Bisecting the kernel tree, revels a seemingly unrelated commit
that when reverted it fixes the problem:

commit 470c66239ef0336429b35345f3f615d47341e13b
Author: David Brownell <dbrownell@users.sourceforge.net>
Date:   Mon Dec 1 14:31:37 2008 -0800

    genirq: warn when IRQF_DISABLED may be ignored
...
iff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index c498a1b..7fd891c 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -635,6 +635,18 @@ int request_irq(unsigned int irq, irq_handler_t handler,
        struct irq_desc *desc;
        int retval;

+       /*
+        * handle_IRQ_event() always ignores IRQF_DISABLED except for
+        * the _first_ irqaction (sigh).  That can cause oopsing, but
+        * the behavior is classified as "will not fix" so we need to
+        * start nudging drivers away from using that idiom.
+        */
+       if ((irqflags & (IRQF_SHARED|IRQF_DISABLED))
+                       == (IRQF_SHARED|IRQF_DISABLED))
+               pr_warning("IRQ %d/%s: IRQF_DISABLED is not "
+                               "guaranteed on shared IRQs\n",
+                               irq, devname);
+
 #ifdef CONFIG_LOCKDEP
        /*
         * Lockdep wants atomic interrupt handlers:

I guess there are some timing issues?

Thanks,
Yehuda

------------------------------------------------------------------------------
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

Re: [uml-devel] Networking issues with 2.6.29

[Nix]

On 26 Mar 2009, Yehuda Sadeh Weinraub spake thusly:

> Network doesn't seem to work for me in 2.6.29, although it was working
> in 2.6.28. System behavior seemed really strange, as it sometimes did
> work when I was using the same uml machine, when using a different
> user. Bisecting the kernel tree, revels a seemingly unrelated commit
> that when reverted it fixes the problem:

I doubt it. This is a known race, particularly easy to reproduce on UP,
fixed by <http://patchwork.kernel.org/patch/14465/>, which causes
networking to go away at seemingly random moments. I had it everywhere
within ten minutes of upgrading...

> commit 470c66239ef0336429b35345f3f615d47341e13b
> Author: David Brownell <dbrownell@users.sourceforge.net>
> Date:   Mon Dec 1 14:31:37 2008 -0800
>
>     genirq: warn when IRQF_DISABLED may be ignored

This patch just adds an (annoying and useless to users) warning that's
printed at interface bringup time. If it makes the problem go away I'll
eat my hat.

------------------------------------------------------------------------------
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel