[PATCH] ARCH 2.6.25.y: Fix 32-bit x86 MSI-X allocation leakage

[PATCH] ARCH 2.6.25.y: Fix 32-bit x86 MSI-X allocation leakage

[PJ Waskiewicz]

This bug was introduced in the 2.6.24 i386/x86_64 tree merge, where
MSI-X vector allocation will eventually fail.  The cause is the new
bit array tracking used vectors is not getting cleared properly on
IRQ destruction on the 32-bit APIC code.

This can be seen easily using the ixgbe 10 GbE driver on multi-core
systems by simply loading and unloading the driver a few times.
Depending on the number of available vectors on the host system, the
MSI-X allocation will eventually fail, and the driver will only be
able to use legacy interrupts.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
---

 arch/x86/kernel/io_apic_32.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)


diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index 4ca5486..f239b30 100644
--- a/arch/x86/kernel/io_apic_32.c
+++ b/arch/x86/kernel/io_apic_32.c
@@ -2477,6 +2477,7 @@ void destroy_irq(unsigned int irq)
 	dynamic_irq_cleanup(irq);
 
 	spin_lock_irqsave(&vector_lock, flags);
+	clear_bit(irq_vector[irq], used_vectors);
 	irq_vector[irq] = 0;
 	spin_unlock_irqrestore(&vector_lock, flags);
 }

Re: [stable] [PATCH] ARCH 2.6.25.y: Fix 32-bit x86 MSI-X allocation leakage

[Greg KH]

On Fri, Apr 25, 2008 at 06:00:26PM -0700, PJ Waskiewicz wrote:
> This bug was introduced in the 2.6.24 i386/x86_64 tree merge, where
> MSI-X vector allocation will eventually fail.  The cause is the new
> bit array tracking used vectors is not getting cleared properly on
> IRQ destruction on the 32-bit APIC code.
> 
> This can be seen easily using the ixgbe 10 GbE driver on multi-core
> systems by simply loading and unloading the driver a few times.
> Depending on the number of available vectors on the host system, the
> MSI-X allocation will eventually fail, and the driver will only be
> able to use legacy interrupts.
> 
> Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
> ---

When sending patches to -stable, please add "CC: stable
<stable@kernel.org> to the patch itself in the signed-off-by area, that
way we get notified automatically when it goes into Linus's tree so that
we can then know to apply it to the tree.  Otherwise it's a tough job to
try to track all of these knowing when to watch out for them to be
committed.

Can you please resend them to stable@kernel.org when they do go into
Linus's tree?

thanks,

greg k-h

RE: [stable] [PATCH] ARCH 2.6.25.y: Fix 32-bit x86 MSI-Xallocation leakage

[Waskiewicz Jr, Peter P]

> When sending patches to -stable, please add "CC: stable 
> <stable@kernel.org> to the patch itself in the signed-off-by 
> area, that way we get notified automatically when it goes 
> into Linus's tree so that we can then know to apply it to the 
> tree.  Otherwise it's a tough job to try to track all of 
> these knowing when to watch out for them to be committed.
> 
> Can you please resend them to stable@kernel.org when they do 
> go into Linus's tree?

Sure thing.

Thanks Greg,

-PJ Waskiewicz