x86/irq: Reorganize the return path in assign_irq_vector

Use an explicit goto for the cases where we have success in the search/update
and return -ENOSPC if the search loop ends due to no space.

Preparatory patch for fixes. No functional change.

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/20151231160106.403491024@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 19082cf..613b1cd 100644 (file)
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -118,13 +118,12 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
         */
        static int current_vector = FIRST_EXTERNAL_VECTOR + VECTOR_OFFSET_START;
        static int current_offset = VECTOR_OFFSET_START % 16;
-       int cpu, err;
+       int cpu;
 
        if (d->move_in_progress)
                return -EBUSY;
 
        /* Only try and allocate irqs on cpus that are present */
-       err = -ENOSPC;
        cpumask_clear(d->old_domain);
        cpumask_clear(searched_cpumask);
        cpu = cpumask_first_and(mask, cpu_online_mask);
@@ -134,9 +133,8 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
                apic->vector_allocation_domain(cpu, vector_cpumask, mask);
 
                if (cpumask_subset(vector_cpumask, d->domain)) {
-                       err = 0;
                        if (cpumask_equal(vector_cpumask, d->domain))
-                               break;
+                               goto success;
                        /*
                         * New cpumask using the vector is a proper subset of
                         * the current in use mask. So cleanup the vector
@@ -147,7 +145,7 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
                        d->move_in_progress =
                           cpumask_intersects(d->old_domain, cpu_online_mask);
                        cpumask_and(d->domain, d->domain, vector_cpumask);
-                       break;
+                       goto success;
                }
 
                vector = current_vector;
@@ -187,17 +185,13 @@ next:
                        per_cpu(vector_irq, new_cpu)[vector] = irq_to_desc(irq);
                d->cfg.vector = vector;
                cpumask_copy(d->domain, vector_cpumask);
-               err = 0;
-               break;
+               goto success;
        }
+       return -ENOSPC;
 
-       if (!err) {
-               /* cache destination APIC IDs into cfg->dest_apicid */
-               err = apic->cpu_mask_to_apicid_and(mask, d->domain,
-                                                  &d->cfg.dest_apicid);
-       }
-
-       return err;
+success:
+       /* cache destination APIC IDs into cfg->dest_apicid */
+       return apic->cpu_mask_to_apicid_and(mask, d->domain, &d->cfg.dest_apicid);
 }
 
 static int assign_irq_vector(int irq, struct apic_chip_data *data,