x86/irq: Get rid of code duplication

Reusing an existing vector and assigning a new vector has duplicated
code. Consolidate it.

This is also a preparatory patch for finally plugging the cleanup race.

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/20151231160106.721599216@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 15 insertions, 18 deletions

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 1bd29c624531..fccfa3f5545c 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -118,7 +118,7 @@ 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;
+        int cpu, vector;
 
         if (d->move_in_progress)
                 return -EBUSY;
@@ -128,7 +128,7 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
         cpumask_clear(searched_cpumask);
         cpu = cpumask_first_and(mask, cpu_online_mask);
         while (cpu < nr_cpu_ids) {
-                int new_cpu, vector, offset;
+                int new_cpu, offset;
 
                 /* Get the possible target cpus for @mask/@cpu from the apic */
                 apic->vector_allocation_domain(cpu, vector_cpumask, mask);
@@ -148,16 +148,12 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
                         if (cpumask_equal(vector_cpumask, d->domain))
                                 goto success;
                         /*
-                         * New cpumask using the vector is a proper subset of
-                         * the current in use mask. So cleanup the vector
-                         * allocation for the members that are not used anymore.
+                         * Mark the cpus which are not longer in the mask for
+                         * cleanup.
                          */
-                        cpumask_andnot(d->old_domain, d->domain,
-                                       vector_cpumask);
-                        d->move_in_progress =
-                           cpumask_intersects(d->old_domain, cpu_online_mask);
-                        cpumask_copy(d->domain, vector_cpumask);
-                        goto success;
+                        cpumask_andnot(d->old_domain, d->domain, vector_cpumask);
+                        vector = d->cfg.vector;
+                        goto update;
                 }
 
                 vector = current_vector;
@@ -183,16 +179,12 @@ next:
                 /* Found one! */
                 current_vector = vector;
                 current_offset = offset;
-                if (d->cfg.vector) {
+                /* Schedule the old vector for cleanup on all cpus */
+                if (d->cfg.vector)
                         cpumask_copy(d->old_domain, d->domain);
-                        d->move_in_progress =
-                           cpumask_intersects(d->old_domain, cpu_online_mask);
-                }
                 for_each_cpu(new_cpu, vector_searchmask)
                         per_cpu(vector_irq, new_cpu)[vector] = irq_to_desc(irq);
-                d->cfg.vector = vector;
-                cpumask_copy(d->domain, vector_cpumask);
-                goto success;
+                goto update;
 
 next_cpu:
                 /*
@@ -209,6 +201,11 @@ next_cpu:
         }
         return -ENOSPC;
 
+update:
+        /* Cleanup required ? */
+        d->move_in_progress = cpumask_intersects(d->old_domain, cpu_online_mask);
+        d->cfg.vector = vector;
+        cpumask_copy(d->domain, vector_cpumask);
 success:
         /*
          * Cache destination APIC IDs into cfg->dest_apicid. This cannot fail