AcoSail/kernel_optimize_test
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cpumask: convert arch/x86/kernel/nmi.c's backtrace_mask to a cpumask_var_t

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Impact: cleanup, reduce memory usage for CONFIG_CPUMASK_OFFSTACK=y

I *think* every path calls check_nmi_watchdog before using the
watchdog, so that's the right place for the initialization.

If that's wrong, we'll get a nice NULL-deref with
CONFIG_CPUMASK_OFFSTACK=y, and have uncovered another bug.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2009-03-13 14:49:49 +10:30
parent bc9b83dd1f
commit fcef8576d8
1 changed files with 6 additions and 5 deletions
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11
arch/x86/kernel/apic/nmi.c
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@ -39,7 +39,7 @@
int unknown_nmi_panic; int unknown_nmi_panic;
int nmi_watchdog_enabled; int nmi_watchdog_enabled;
static cpumask_t backtrace_mask = CPU_MASK_NONE; static cpumask_var_t backtrace_mask;
/* nmi_active: /* nmi_active:
* >0: the lapic NMI watchdog is active, but can be disabled * >0: the lapic NMI watchdog is active, but can be disabled
@ -138,6 +138,7 @@ int __init check_nmi_watchdog(void)
if (!prev_nmi_count) if (!prev_nmi_count)
goto error; goto error;
alloc_cpumask_var(&backtrace_mask, GFP_KERNEL);
printk(KERN_INFO "Testing NMI watchdog ... "); printk(KERN_INFO "Testing NMI watchdog ... ");
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
@ -413,14 +414,14 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
touched = 1; touched = 1;
} }
if (cpu_isset(cpu, backtrace_mask)) { if (cpumask_test_cpu(cpu, backtrace_mask)) {
static DEFINE_SPINLOCK(lock); /* Serialise the printks */ static DEFINE_SPINLOCK(lock); /* Serialise the printks */
spin_lock(&lock); spin_lock(&lock);
printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu); printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
dump_stack(); dump_stack();
spin_unlock(&lock); spin_unlock(&lock);
cpu_clear(cpu, backtrace_mask); cpumask_clear_cpu(cpu, backtrace_mask);
} }
/* Could check oops_in_progress here too, but it's safer not to */ /* Could check oops_in_progress here too, but it's safer not to */
@ -554,10 +555,10 @@ void __trigger_all_cpu_backtrace(void)
{ {
int i; int i;
backtrace_mask = cpu_online_map; cpumask_copy(backtrace_mask, cpu_online_mask);
/* Wait for up to 10 seconds for all CPUs to do the backtrace */ /* Wait for up to 10 seconds for all CPUs to do the backtrace */
for (i = 0; i < 10 * 1000; i++) { for (i = 0; i < 10 * 1000; i++) {
if (cpus_empty(backtrace_mask)) if (cpumask_empty(backtrace_mask))
break; break;
mdelay(1); mdelay(1);
} }