This is a note to let you know that I've just added the patch titled
irqchip: armada-370-xp: fix MSI race condition
to the 3.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
irqchip-armada-370-xp-fix-msi-race-condition.patch
and it can be found in the queue-3.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c7f7bd4a136e4b02dd2a66bf95aec545bd93e8db Mon Sep 17 00:00:00 2001
From: Lior Amsalem <alior@xxxxxxxxxxx>
Date: Mon, 25 Nov 2013 17:26:45 +0100
Subject: irqchip: armada-370-xp: fix MSI race condition
From: Lior Amsalem <alior@xxxxxxxxxxx>
commit c7f7bd4a136e4b02dd2a66bf95aec545bd93e8db upstream.
In the Armada 370/XP driver, when we receive an IRQ 1, we read the
list of doorbells that caused the interrupt from register
ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of MSIs that
were generated. However, instead of acknowledging only the MSIs that
were generated, we acknowledge *all* the MSIs, by writing
~MSI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register.
This creates a race condition: if a new MSI that isn't part of the
ones read into the temporary "msimask" variable is fired before we
acknowledge all MSIs, then we will simply loose it.
It is important to mention that this ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS
register has the following behavior: "A CPU write of 0 clears the bits
in this field. A CPU write of 1 has no effect". This is what allows us
to simply write ~msimask to acknoledge the handled MSIs.
Notice that the same problem is present in the IPI implementation, but
it is fixed as a separate patch, so that this IPI fix can be pushed to
older stable versions as appropriate (all the way to 3.8), while the
MSI code only appeared in 3.13.
Signed-off-by: Lior Amsalem <alior@xxxxxxxxxxx>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason Cooper <jason@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/irqchip/irq-armada-370-xp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/irqchip/irq-armada-370-xp.c
+++ b/drivers/irqchip/irq-armada-370-xp.c
@@ -381,7 +381,7 @@ armada_370_xp_handle_irq(struct pt_regs
ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS)
& PCI_MSI_DOORBELL_MASK;
- writel(~PCI_MSI_DOORBELL_MASK, per_cpu_int_base +
+ writel(~msimask, per_cpu_int_base +
ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS);
for (msinr = PCI_MSI_DOORBELL_START;
Patches currently in stable-queue which might be from alior@xxxxxxxxxxx are
queue-3.13/irqchip-armada-370-xp-fix-ipi-race-condition.patch
queue-3.13/irqchip-armada-370-xp-fix-msi-race-condition.patch
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