From 95ffeb4b5baca266e1d0d2bc90f1513e6f419cdd Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 31 Dec 2015 16:30:47 +0000
Subject: [PATCH] x86/irq: Reorganize the search in assign_irq_vector
Split out the code which advances the target cpu for the search so we can
reuse it for the next patch which adds an early validation check for the
vectormask which we get from the apic.
Add comments while at it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Borislav Petkov <bp@alien8.de>
Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jeremiah Mahler <jmmahler@gmail.com>
Cc: andy.shevchenko@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: stable@vger.kernel.org #4.3+
Link: http://lkml.kernel.org/r/20151231160106.484562040@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/apic/vector.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 613b1cd8eecb..cef31955ab18 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -157,14 +157,9 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
vector = FIRST_EXTERNAL_VECTOR + offset;
}
- if (unlikely(current_vector == vector)) {
- cpumask_or(searched_cpumask, searched_cpumask,
- vector_cpumask);
- cpumask_andnot(vector_cpumask, mask, searched_cpumask);
- cpu = cpumask_first_and(vector_cpumask,
- cpu_online_mask);
- continue;
- }
+ /* If the search wrapped around, try the next cpu */
+ if (unlikely(current_vector == vector))
+ goto next_cpu;
if (test_bit(vector, used_vectors))
goto next;
@@ -186,6 +181,19 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
d->cfg.vector = vector;
cpumask_copy(d->domain, vector_cpumask);
goto success;
+
+next_cpu:
+ /*
+ * We exclude the current @vector_cpumask from the requested
+ * @mask and try again with the next online cpu in the
+ * result. We cannot modify @mask, so we use @vector_cpumask
+ * as a temporary buffer here as it will be reassigned when
+ * calling apic->vector_allocation_domain() above.
+ */
+ cpumask_or(searched_cpumask, searched_cpumask, vector_cpumask);
+ cpumask_andnot(vector_cpumask, mask, searched_cpumask);
+ cpu = cpumask_first_and(vector_cpumask, cpu_online_mask);
+ continue;
}
return -ENOSPC;
--
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