used_vectors is a bitmap for vectors that are not tracked in per_cpu
vector_irq.
used_vectors contains information on the first 32 exceptions, the system
vectors.
the IA32_SYSCALL_VECTOR (0x80), and the IRQ_MOVE_CLEANUP_VECTOR (0x20).
assign_irq_vectors() assigns vectors up to first_system_vector and
it will not use vectors that are set used_vectors.
This patch modifies the code to scan up to first_system_vector
and do a test on the used_vectors bitmap.
So count avaiable vectors correctly.
-v2: fix compiling problem.
-v3: update changelog and commets
Signed-off-by: Yinghai Lu <ying...@kernel.org>
---
arch/x86/kernel/irq.c | 18 ++++++++++++++++--
1 file changed, 16 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
@@ -17,6 +17,7 @@
#include <asm/idle.h>
#include <asm/mce.h>
#include <asm/hw_irq.h>
+#include <asm/desc.h>
#define CREATE_TRACE_POINTS
#include <asm/trace/irq_vectors.h>
@@ -321,8 +322,21 @@ 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 scan per_cpu vectors from
+ * FIRST_EXTERNAL_VECTOR to first_system_vector.
+ * It aslo skip vectors that are set in used_vectors bitmask.
+ * used_vectors could have bits set for
+ * IA32_SYSCALL_VECTOR (0x80)
+ * IRQ_MOVE_CLEANUP_VECTOR (0x20)
+ * Don't count those as available vectors.
+ */
+ 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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