1 files changed, 10 insertions, 6 deletions

diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index 3bdd38ec71da..207bc511a6e3 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -19,7 +19,6 @@
 #include <asm/irq.h>
 
 /*
- * Simple hash strategy: index = code & 0xff;
  * ext_int_hash[index] is the start of the list for all external interrupts
  * that hash to this index. With the current set of external interrupts 
  * (0x1202 external call, 0x1004 cpu timer, 0x2401 hwc console, 0x4000
@@ -27,6 +26,11 @@
  */
 ext_int_info_t *ext_int_hash[256] = { 0, };
 
+static inline int ext_hash(__u16 code)
+{
+        return (code + (code >> 9)) & 0xff;
+}
+
 int register_external_interrupt(__u16 code, ext_int_handler_t handler)
 {
         ext_int_info_t *p;
@@ -37,7 +41,7 @@ int register_external_interrupt(__u16 code, ext_int_handler_t handler)
                 return -ENOMEM;
         p->code = code;
         p->handler = handler;
-        index = code & 0xff;
+        index = ext_hash(code);
         p->next = ext_int_hash[index];
         ext_int_hash[index] = p;
         return 0;
@@ -52,7 +56,7 @@ int register_early_external_interrupt(__u16 code, ext_int_handler_t handler,
                 return -EINVAL;
         p->code = code;
         p->handler = handler;
-        index = code & 0xff;
+        index = ext_hash(code);
         p->next = ext_int_hash[index];
         ext_int_hash[index] = p;
         return 0;
@@ -63,7 +67,7 @@ int unregister_external_interrupt(__u16 code, ext_int_handler_t handler)
         ext_int_info_t *p, *q;
         int index;
 
-        index = code & 0xff;
+        index = ext_hash(code);
         q = NULL;
         p = ext_int_hash[index];
         while (p != NULL) {
@@ -90,7 +94,7 @@ int unregister_early_external_interrupt(__u16 code, ext_int_handler_t handler,
 
         if (p == NULL || p->code != code || p->handler != handler)
                 return -EINVAL;
-        index = code & 0xff;
+        index = ext_hash(code);
         q = ext_int_hash[index];
         if (p != q) {
                 while (q != NULL) {
@@ -120,7 +124,7 @@ void do_extint(struct pt_regs *regs, unsigned short code)
                  */
                 account_ticks(regs);
         kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
-        index = code & 0xff;
+        index = ext_hash(code);
         for (p = ext_int_hash[index]; p; p = p->next) {
                 if (likely(p->code == code)) {
                         if (likely(p->handler))