linux-kernel - [patch] MSI-X: fix resume crash

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Date:	Wed, 28 Mar 2007 15:06:30 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Adrian Bunk <bunk@...sta.de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Thomas Meyer <thomas@...3r.de>,
	Frederic Riss <frederic.riss@...il.com>,
	Marcus Better <marcus@...ter.se>, Len Brown <lenb@...nel.org>
Subject: [patch] MSI-X: fix resume crash


* Ingo Molnar <mingo@...e.hu> wrote:

> [...] I'll now re-test Eric's MSI patch.

Eric's patch seems to have done the trick on my T60: i've done 10 
suspend+resumes and each worked fine. I've tidied up the description 
part of Eric's patch a bit for upstream application - find it below.

	Ingo

---------------------->
Subject: [patch] MSI-X: fix resume crash
From: Eric W. Biederman <ebiederm@...ssion.com>

I think the right solution is to simply make pci_enable_device just flip 
enable bits and move the rest of the work someplace else.

However a thorough cleanup is a little extreme for this point in the 
release cycle, so I think a quick hack that makes the code not stomp the 
irq when msi irq's are enabled should be the first fix.  Then we can 
later make the code not change the irqs at all.

Tony, Len the way pci_disable_device is being used in a suspend/resume 
path by a few drivers is completely incompatible with the way irqs are 
allocated on ia64.  In particular people the following sequence occurs 
in several drivers.

probe:
  pci_enable_device(pdev);
  request_irq(pdev->irq);
suspend:
  pci_disable_device(pdev);
resume:
  pci_enable_device(pdev);
remove:
  free_irq(pdev->irq);
  pci_disable_device(pdev);

What I'm proposing we do is move the irq allocation code out of 
pci_enable_device and the irq freeing code out of pci_disable_device in 
the future.  If we move ia64 to a model where the irq number equal the 
gsi like we have for x86_64 and are in the middle of for i386 that 
should be pretty straight forward.  It would even be relatively simple 
to delay vector allocation in that context until request_irq, if we 
needed the delayed allocation benefit.  Do you two have any problems 
with moving in that direction?

If fixing the arch code is unacceptable for some reason I'm not aware of 
we need to audit the 10-20 drivers that call pci_disable_device in their 
suspend/resume processing and ensure that they have freed all of the 
irqs before that point.  Given that I have bug reports on the msi path I 
know that isn't true.

From: Eric W. Biederman <ebiederm@...ssion.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/cris/arch-v32/drivers/pci/bios.c |    4 +++-
 arch/frv/mb93090-mb00/pci-vdk.c       |    3 ++-
 arch/i386/pci/common.c                |    6 ++++--
 arch/ia64/pci/pci.c                   |    8 ++++++--
 4 files changed, 15 insertions(+), 6 deletions(-)

Index: linux/arch/cris/arch-v32/drivers/pci/bios.c
===================================================================
--- linux.orig/arch/cris/arch-v32/drivers/pci/bios.c
+++ linux/arch/cris/arch-v32/drivers/pci/bios.c
@@ -100,7 +100,9 @@ int pcibios_enable_device(struct pci_dev
 	if ((err = pcibios_enable_resources(dev, mask)) < 0)
 		return err;
 
-	return pcibios_enable_irq(dev);
+	if (!dev->msi_enabled)
+		pcibios_enable_irq(dev);
+	return 0;
 }
 
 int pcibios_assign_resources(void)
Index: linux/arch/frv/mb93090-mb00/pci-vdk.c
===================================================================
--- linux.orig/arch/frv/mb93090-mb00/pci-vdk.c
+++ linux/arch/frv/mb93090-mb00/pci-vdk.c
@@ -466,6 +466,7 @@ int pcibios_enable_device(struct pci_dev
 
 	if ((err = pcibios_enable_resources(dev, mask)) < 0)
 		return err;
-	pcibios_enable_irq(dev);
+	if (!dev->msi_enabled)
+		pcibios_enable_irq(dev);
 	return 0;
 }
Index: linux/arch/i386/pci/common.c
===================================================================
--- linux.orig/arch/i386/pci/common.c
+++ linux/arch/i386/pci/common.c
@@ -434,11 +434,13 @@ int pcibios_enable_device(struct pci_dev
 	if ((err = pcibios_enable_resources(dev, mask)) < 0)
 		return err;
 
-	return pcibios_enable_irq(dev);
+	if (!dev->msi_enabled)
+		return pcibios_enable_irq(dev);
+	return 0;
 }
 
 void pcibios_disable_device (struct pci_dev *dev)
 {
-	if (pcibios_disable_irq)
+	if (!dev->msi_enabled && pcibios_disable_irq)
 		pcibios_disable_irq(dev);
 }
Index: linux/arch/ia64/pci/pci.c
===================================================================
--- linux.orig/arch/ia64/pci/pci.c
+++ linux/arch/ia64/pci/pci.c
@@ -557,14 +557,18 @@ pcibios_enable_device (struct pci_dev *d
 	if (ret < 0)
 		return ret;
 
-	return acpi_pci_irq_enable(dev);
+	if (!dev->msi_enabled)
+		return acpi_pci_irq_enable(dev);
+	return 0;
 }
 
 void
 pcibios_disable_device (struct pci_dev *dev)
 {
 	BUG_ON(atomic_read(&dev->enable_cnt));
-	acpi_pci_irq_disable(dev);
+	if (!dev->msi_enabled)
+		acpi_pci_irq_disable(dev);
+	return 0;
 }
 
 void
-
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