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authorThomas Gleixner <tglx@linutronix.de>2014-04-16 14:36:44 +0000
committerThomas Gleixner <tglx@linutronix.de>2014-04-17 23:36:27 +0200
commit01f8fa4f01d8362358eb90e412bd7ae18a3ec1ad (patch)
treec6b5f7c2ae3e1488d900907ae8369967469af8d5 /include/linux/interrupt.h
parent81cef0fe19e086ff6abfd45e92246f68ffa0185f (diff)
genirq: Allow forcing cpu affinity of interrupts
The current implementation of irq_set_affinity() refuses rightfully to route an interrupt to an offline cpu. But there is a special case, where this is actually desired. Some of the ARM SoCs have per cpu timers which require setting the affinity during cpu startup where the cpu is not yet in the online mask. If we can't do that, then the local timer interrupt for the about to become online cpu is routed to some random online cpu. The developers of the affected machines tried to work around that issue, but that results in a massive mess in that timer code. We have a yet unused argument in the set_affinity callbacks of the irq chips, which I added back then for a similar reason. It was never required so it got not used. But I'm happy that I never removed it. That allows us to implement a sane handling of the above scenario. So the affected SoC drivers can add the required force handling to their interrupt chip, switch the timer code to irq_force_affinity() and things just work. This does not affect any existing user of irq_set_affinity(). Tagged for stable to allow a simple fix of the affected SoC clock event drivers. Reported-and-tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Tomasz Figa <t.figa@samsung.com>, Cc: Daniel Lezcano <daniel.lezcano@linaro.org>, Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: linux-arm-kernel@lists.infradead.org, Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20140416143315.717251504@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/interrupt.h')
-rw-r--r--include/linux/interrupt.h35
1 files changed, 34 insertions, 1 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index c7bfac1c4a7b..8834a7e5b944 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -203,7 +203,40 @@ static inline int check_wakeup_irqs(void) { return 0; }
extern cpumask_var_t irq_default_affinity;
-extern int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask);
+/* Internal implementation. Use the helpers below */
+extern int __irq_set_affinity(unsigned int irq, const struct cpumask *cpumask,
+ bool force);
+
+/**
+ * irq_set_affinity - Set the irq affinity of a given irq
+ * @irq: Interrupt to set affinity
+ * @mask: cpumask
+ *
+ * Fails if cpumask does not contain an online CPU
+ */
+static inline int
+irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
+{
+ return __irq_set_affinity(irq, cpumask, false);
+}
+
+/**
+ * irq_force_affinity - Force the irq affinity of a given irq
+ * @irq: Interrupt to set affinity
+ * @mask: cpumask
+ *
+ * Same as irq_set_affinity, but without checking the mask against
+ * online cpus.
+ *
+ * Solely for low level cpu hotplug code, where we need to make per
+ * cpu interrupts affine before the cpu becomes online.
+ */
+static inline int
+irq_force_affinity(unsigned int irq, const struct cpumask *cpumask)
+{
+ return __irq_set_affinity(irq, cpumask, true);
+}
+
extern int irq_can_set_affinity(unsigned int irq);
extern int irq_select_affinity(unsigned int irq);