Commit cd77b5ce208c ("Fix the frequency read by /proc/cpuinfo")
to fix /proc/cpuinfo on POWERNV triggered a sleeping-in-atomic section
warning. This was because the place where we cpufreq_get (which takes
an rwsem) from show_cpuinfo is in a preempt_disabled. However, the
preempt_disable() in show_cpuinfo is for protection against
CPU-Hotplug, since we don't want to report the information of offline
CPUs in /proc/cpuinfo.
Fix this by replacing preempt_disable()/preempt_enable() in
show_cpuinfo() by get_online_cpus()/put_online_cpus() giving a proper
protection against CPU-Hotplug.
---
arch/powerpc/kernel/setup-common.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/setup-common.c
b/arch/powerpc/kernel/setup-common.c
index 2075322..f772442 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -244,9 +244,9 @@ static int show_cpuinfo(struct seq_file *m, void *v)
/* We only show online cpus: disable preempt (overzealous, I
* knew) to prevent cpu going down. */
- preempt_disable();
+ get_online_cpus();
if (!cpu_online(cpu_id)) {
- preempt_enable();
+ put_online_cpus();
return 0;
}
@@ -359,7 +359,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
seq_printf(m, "\n");
#endif
- preempt_enable();
+ put_online_cpus();
/* If this is the last cpu, print the summary */
if (cpumask_next(cpu_id, cpu_online_mask) >= nr_cpu_ids)
--
1.9.1
