[PATCH] x86, irq: get correct available vectors for cpu disable

From: Yinghai Lu
Date: Sun Jan 26 2014 - 15:34:23 EST


assign_irq_vector will stop before first_system_vector.
also it will not vector that is set in used_vectors.

used_vectors is used to track non per_cpu irq_vector in vector_irq.
It include first 32 exception [0,1f) and system vector near 0xfe.
and IA32_SYSCALL_VECTOR (0x80), IRQ_MOVE_CLEANUP_VECTOR (0x20).

So add checking for them for counting avaiable vectors.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
arch/x86/kernel/irq.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/kernel/irq.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/irq.c
+++ linux-2.6/arch/x86/kernel/irq.c
@@ -321,8 +321,19 @@ int check_irq_vectors_for_cpu_disable(vo
for_each_online_cpu(cpu) {
if (cpu == this_cpu)
continue;
- for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS;
- vector++) {
+
+ /*
+ * assign_irq_vector() only use vector under
+ * first_system_vector and not set in used_vectors bitmask.
+ * used_vectors could have bits set for
+ * IA32_SYSCALL_VECTOR (0x80)
+ * IRQ_MOVE_CLEANUP_VECTOR (0x20)
+ */
+ for (vector = FIRST_EXTERNAL_VECTOR;
+ vector < first_system_vector; vector++) {
+ if (test_bit(vector, used_vectors)
+ continue;
+
if (per_cpu(vector_irq, cpu)[vector] < 0)
count++;
}
--
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