[Xen-devel] [PATCH 3 of 3] IRQ: Introduce old_vector to irq_cfg

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Introduce old_vector to irq_cfg with the same principle as
old_cpu_mask.  This removes a brute force loop from
__clear_irq_vector(), and paves the way to correct bitrotten logic
elsewhere in the irq code.

Signed-off-by Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

diff -r cf93a1825d66 -r 1a244d4ca6ac xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c    Fri Sep 02 17:33:17 2011 +0100
+++ b/xen/arch/x86/io_apic.c    Fri Sep 02 17:33:17 2011 +0100
@@ -487,11 +487,16 @@ fastcall void smp_irq_move_cleanup_inter
         __get_cpu_var(vector_irq)[vector] = -1;
         cfg->move_cleanup_count--;
 
-        if ( cfg->move_cleanup_count == 0 
-             &&  cfg->used_vectors )
+        if ( cfg->move_cleanup_count == 0 )
         {
-            ASSERT(test_bit(vector, cfg->used_vectors));
-            clear_bit(vector, cfg->used_vectors);
+            cfg->old_vector = -1;
+            cpus_clear(cfg->old_cpu_mask);
+
+            if ( cfg->used_vectors )
+            {
+                ASSERT(test_bit(vector, cfg->used_vectors));
+                clear_bit(vector, cfg->used_vectors);
+            }
         }
 unlock:
         spin_unlock(&desc->lock);
diff -r cf93a1825d66 -r 1a244d4ca6ac xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c        Fri Sep 02 17:33:17 2011 +0100
+++ b/xen/arch/x86/irq.c        Fri Sep 02 17:33:17 2011 +0100
@@ -211,15 +211,9 @@ static void __clear_irq_vector(int irq)
 
     cpus_and(tmp_mask, cfg->old_cpu_mask, cpu_online_map);
     for_each_cpu_mask(cpu, tmp_mask) {
-        for (vector = FIRST_DYNAMIC_VECTOR; vector <= LAST_DYNAMIC_VECTOR;
-                                vector++) {
-            if (per_cpu(vector_irq, cpu)[vector] != irq)
-                continue;
-            TRACE_3D(TRC_HW_IRQ_MOVE_FINISH,
-                     irq, vector, cpu);
-            per_cpu(vector_irq, cpu)[vector] = -1;
-             break;
-        }
+        ASSERT( per_cpu(vector_irq, cpu)[cfg->old_vector] == irq );
+        TRACE_3D(TRC_HW_IRQ_MOVE_FINISH, irq, vector, cpu);
+        per_cpu(vector_irq, cpu)[vector] = -1;
      }
 
     if ( cfg->used_vectors )
@@ -279,6 +273,7 @@ static void __init init_one_irq_desc(str
 static void __init init_one_irq_cfg(struct irq_cfg *cfg)
 {
     cfg->vector = IRQ_VECTOR_UNASSIGNED;
+    cfg->old_vector = IRQ_VECTOR_UNASSIGNED;
     cpus_clear(cfg->cpu_mask);
     cpus_clear(cfg->old_cpu_mask);
     cfg->used_vectors = NULL;
@@ -418,6 +413,7 @@ next:
         if (old_vector) {
             cfg->move_in_progress = 1;
             cpus_copy(cfg->old_cpu_mask, cfg->cpu_mask);
+            cfg->old_vector = cfg->vector;
         }
         trace_irq_mask(TRC_HW_IRQ_ASSIGN_VECTOR, irq, vector, &tmp_mask);
         for_each_cpu_mask(new_cpu, tmp_mask)
diff -r cf93a1825d66 -r 1a244d4ca6ac xen/include/asm-x86/irq.h
--- a/xen/include/asm-x86/irq.h Fri Sep 02 17:33:17 2011 +0100
+++ b/xen/include/asm-x86/irq.h Fri Sep 02 17:33:17 2011 +0100
@@ -28,7 +28,8 @@ typedef struct {
 } vmask_t;
 
 struct irq_cfg {
-        int  vector;
+        s16 vector;                  /* vector itself is only 8 bits, */
+        s16 old_vector;              /* but we use -1 for unassigned  */
         cpumask_t cpu_mask;
         cpumask_t old_cpu_mask;
         unsigned move_cleanup_count;

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