diff options
Diffstat (limited to 'target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch')
| -rw-r--r-- | target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch b/target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch new file mode 100644 index 0000000000..336ad8d758 --- /dev/null +++ b/target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch @@ -0,0 +1,46 @@ +From 60b78d28057f9f1ecce39955755d26e4cd3130de Mon Sep 17 00:00:00 2001 +From: Lior Amsalem <alior@marvell.com> +Date: Mon, 25 Nov 2013 17:26:44 +0100 +Subject: [PATCH 085/203] irqchip: armada-370-xp: fix IPI race condition + +In the Armada 370/XP driver, when we receive an IRQ 0, we read the +list of doorbells that caused the interrupt from register +ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of IPIs that +were generated. However, instead of acknowledging only the IPIs that +were generated, we acknowledge *all* the IPIs, by writing +~IPI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register. + +This creates a race condition: if a new IPI that isn't part of the +ones read into the temporary "ipimask" variable is fired before we +acknowledge all IPIs, then we will simply loose it. This is causing +scheduling hangs on SMP intensive workloads. + +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 ~ipimask to acknoledge the handled IPIs. + +Notice that the same problem is present in the MSI implementation, but +it will be 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@marvell.com> +Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> +Cc: stable@vger.kernel.org +Cc: Thomas Gleixner <tglx@linutronix.de> +--- + 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 +@@ -407,7 +407,7 @@ armada_370_xp_handle_irq(struct pt_regs + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS) + & IPI_DOORBELL_MASK; + +- writel(~IPI_DOORBELL_MASK, per_cpu_int_base + ++ writel(~ipimask, per_cpu_int_base + + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS); + + /* Handle all pending doorbells */ |