cpumask: Avoid cpumask_t in arch/x86/kernel/apic/nmi.c

Ingo wants the certainty of a static cpumask (rather than a
cpumask_var_t), but cpumask_t will some day be undefined to
avoid on-stack declarations.

This is what DECLARE_BITMAP/to_cpumask() is for.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <200911031453.52394.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 5 deletions

diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c
index 7ff61d6a188a..6389432a9dbf 100644
--- a/arch/x86/kernel/apic/nmi.c
+++ b/arch/x86/kernel/apic/nmi.c
@@ -39,7 +39,8 @@
 int unknown_nmi_panic;
 int nmi_watchdog_enabled;
 
-static cpumask_t backtrace_mask __read_mostly;
+/* For reliability, we're prepared to waste bits here. */
+static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
 
 /* nmi_active:
  * >0: the lapic NMI watchdog is active, but can be disabled
@@ -414,7 +415,7 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
         }
 
         /* We can be called before check_nmi_watchdog, hence NULL check. */
-        if (cpumask_test_cpu(cpu, &backtrace_mask)) {
+        if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
                 static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
 
                 spin_lock(&lock);
@@ -422,7 +423,7 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
                 show_regs(regs);
                 dump_stack();
                 spin_unlock(&lock);
-                cpumask_clear_cpu(cpu, &backtrace_mask);
+                cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 
                 rc = 1;
         }
@@ -558,14 +559,14 @@ void arch_trigger_all_cpu_backtrace(void)
 {
         int i;
 
-        cpumask_copy(&backtrace_mask, cpu_online_mask);
+        cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
 
         printk(KERN_INFO "sending NMI to all CPUs:\n");
         apic->send_IPI_all(NMI_VECTOR);
 
         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
         for (i = 0; i < 10 * 1000; i++) {
-                if (cpumask_empty(&backtrace_mask))
+                if (cpumask_empty(to_cpumask(backtrace_mask)))
                         break;
                 mdelay(1);
         }