irq/matrix: Split out the CPU selection code into a helper

Linux finds the CPU which has the lowest vector allocation count to spread
out the non managed interrupts across the possible target CPUs, but does
not do so for managed interrupts.

Split out the CPU selection code into a helper function for reuse. No
functional change.

Signed-off-by: Dou Liyang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
index 5092494bf26140dbc367472dbe00841790b95f51..67768bbe736ed3a4f4d9dc51d4dd45c74ad63f92 100644 (file)
--- a/kernel/irq/matrix.c
+++ b/kernel/irq/matrix.c
@@ -124,6 +124,27 @@ static unsigned int matrix_alloc_area(struct irq_matrix *m, struct cpumap *cm,
        return area;
 }
 
+/* Find the best CPU which has the lowest vector allocation count */
+static unsigned int matrix_find_best_cpu(struct irq_matrix *m,
+                                       const struct cpumask *msk)
+{
+       unsigned int cpu, best_cpu, maxavl = 0;
+       struct cpumap *cm;
+
+       best_cpu = UINT_MAX;
+
+       for_each_cpu(cpu, msk) {
+               cm = per_cpu_ptr(m->maps, cpu);
+
+               if (!cm->online || cm->available <= maxavl)
+                       continue;
+
+               best_cpu = cpu;
+               maxavl = cm->available;
+       }
+       return best_cpu;
+}
+
 /**
  * irq_matrix_assign_system - Assign system wide entry in the matrix
  * @m:         Matrix pointer
@@ -322,37 +343,27 @@ void irq_matrix_remove_reserved(struct irq_matrix *m)
 int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk,
                     bool reserved, unsigned int *mapped_cpu)
 {
-       unsigned int cpu, best_cpu, maxavl = 0;
+       unsigned int cpu, bit;
        struct cpumap *cm;
-       unsigned int bit;
 
-       best_cpu = UINT_MAX;
-       for_each_cpu(cpu, msk) {
-               cm = per_cpu_ptr(m->maps, cpu);
-
-               if (!cm->online || cm->available <= maxavl)
-                       continue;
+       cpu = matrix_find_best_cpu(m, msk);
+       if (cpu == UINT_MAX)
+               return -ENOSPC;
 
-               best_cpu = cpu;
-               maxavl = cm->available;
-       }
+       cm = per_cpu_ptr(m->maps, cpu);
+       bit = matrix_alloc_area(m, cm, 1, false);
+       if (bit >= m->alloc_end)
+               return -ENOSPC;
+       cm->allocated++;
+       cm->available--;
+       m->total_allocated++;
+       m->global_available--;
+       if (reserved)
+               m->global_reserved--;
+       *mapped_cpu = cpu;
+       trace_irq_matrix_alloc(bit, cpu, m, cm);
+       return bit;
 
-       if (maxavl) {
-               cm = per_cpu_ptr(m->maps, best_cpu);
-               bit = matrix_alloc_area(m, cm, 1, false);
-               if (bit < m->alloc_end) {
-                       cm->allocated++;
-                       cm->available--;
-                       m->total_allocated++;
-                       m->global_available--;
-                       if (reserved)
-                               m->global_reserved--;
-                       *mapped_cpu = best_cpu;
-                       trace_irq_matrix_alloc(bit, best_cpu, m, cm);
-                       return bit;
-               }
-       }
-       return -ENOSPC;
 }
 
 /**