diff mbox

Regression: Bisected, IRQ and MSI allocations screwed without sparse irq

Message ID Pine.LNX.4.64.0811212022520.29808@ask.diku.dk
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Jesper Dangaard Brouer Nov. 21, 2008, 7:35 p.m. UTC 
On Fri, 21 Nov 2008, Thomas Gleixner wrote:

> On Fri, 21 Nov 2008, Jesper Dangaard Brouer wrote:
>>> Can you please try the attached patch ?
>>
>> I have tried the patch and it solved the problem! :-)
>>
>> I'll gladly test other patches from your.  Guess this patch needs to be
>> brushed up before a mainline patch is ready.
>
> Ok, I queue it for mainline. This solves just the number of irqs
> limitation, the rmmod problem still persists, right ?

It solves both the irq limit and the NIU driver unload bug.

We should give it a good description.
I have cooked up a patch with a description below, will you accept that?

Who's tree do you want it to go upsteam via?
(You are listed as one of the X86 maintainers, but Ingo's tree seems more 
up-to-date. My patch below is agains DaveM's tree)

Cheers,
   Jesper Brouer

--
-------------------------------------------------------------------
MSc. Master of Computer Science
Dept. of Computer Science, University of Copenhagen
Author of http://www.adsl-optimizer.dk
-------------------------------------------------------------------

Fixing irq limit and NIU driver unload bug.

Removing the config option HAVE_SPARSE_IRQ (commit
3235e936c0cc3589309280b6f59e5096779adae3) revealed a regression that
limited the number of irqs on the system.

Besides limiting the number of IRQ, this also caused unloading of the
NIU driver to fail during msi_free_irqs(). The reduced number of IRQs
caused the NIU driver to use "IO-APIC" based IRQs instead of
"PCI-MSI-edge".

This patch changes probe_nr_irqs() to return NR_IRQS, which is
basically the same as the NOT CONFIG_X86_IO_APIC case.  Thus being
fairly safe.

Thus, solving both the irq limit and the NIU driver unload bug.

Tested-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
  arch/x86/kernel/io_apic.c |   22 +---------------------
  1 files changed, 1 insertions(+), 21 deletions(-)

Comments

Thomas Gleixner Nov. 21, 2008, 9:11 p.m. UTC | #1 
On Fri, 21 Nov 2008, Jesper Dangaard Brouer wrote:
> > Ok, I queue it for mainline. This solves just the number of irqs
> > limitation, the rmmod problem still persists, right ?
> 
> It solves both the irq limit and the NIU driver unload bug.

I don't believe that it solves it. It hides it at the best.
 
> We should give it a good description.
> I have cooked up a patch with a description below, will you accept that?
> 
> Who's tree do you want it to go upsteam via?
> (You are listed as one of the X86 maintainers, but Ingo's tree seems more
> up-to-date. My patch below is agains DaveM's tree)

I queued it already with a description of the irq nr. problem. 

The rmmod problem is something different and should be investigated
thoroughly instead of declaring it solved by magic.
 
Thanks,

	tglx
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David Miller Nov. 21, 2008, 11:06 p.m. UTC | #2 
From: Jesper Dangaard Brouer <hawk@diku.dk>
Date: Fri, 21 Nov 2008 20:35:32 +0100 (CET)

> On Fri, 21 Nov 2008, Thomas Gleixner wrote:
> 
> > On Fri, 21 Nov 2008, Jesper Dangaard Brouer wrote:
> >>> Can you please try the attached patch ?
> >>
> >> I have tried the patch and it solved the problem! :-)
> >>
> >> I'll gladly test other patches from your.  Guess this patch needs to be
> >> brushed up before a mainline patch is ready.
> >
> > Ok, I queue it for mainline. This solves just the number of irqs
> > limitation, the rmmod problem still persists, right ?
> 
> It solves both the irq limit and the NIU driver unload bug.

I think it "solves" the unload BUG because the driver never has
to fallback to IO_APIC irqs and abort trying to use MSI-X
any longer.

Only the IRQ limit bug is fixed by Thomas's patch.
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diff mbox

Patch

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index c9513e1..1fec0f9 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3608,27 +3608,7 @@  int __init io_apic_get_redir_entries (int ioapic)

  int __init probe_nr_irqs(void)
  {
-	int idx;
-	int nr = 0;
-#ifndef CONFIG_XEN
-	int nr_min = 32;
-#else
-	int nr_min = NR_IRQS;
-#endif
-
-	for (idx = 0; idx < nr_ioapics; idx++)
-		nr += io_apic_get_redir_entries(idx) + 1;
-
-	/* double it for hotplug and msi and nmi */
-	nr <<= 1;
-
-	/* something wrong ? */
-	if (nr < nr_min)
-		nr = nr_min;
-	if (WARN_ON(nr > NR_IRQS))
-		nr = NR_IRQS;
-
-	return nr;
+	return NR_IRQS;
  }

  /* --------------------------------------------------------------------------