stable 3-10-3: strange output of "lsmod | grep ^acpi_cpufreq"

Commit Message

Rafael Wysocki July 28, 2013, 10:11 p.m. UTC

On Sunday, July 28, 2013 12:21:22 PM Toralf Förster wrote:
> On 07/28/2013 01:39 AM, Rafael J. Wysocki wrote:
> > On Saturday, July 27, 2013 07:40:34 PM Toralf Förster wrote:
> >> it gives at a ThinkPad T420:
> >>
> >> tfoerste@n22 ~/tmp $ lsmod | grep ^acpi_cpufreq
> >> acpi_cpufreq           12902  2147483647
> > 
> > That is -1, which indicates some module refcount woes.
> 
> yes, ofc.
> 
> The issue apears after 1 s2ram/resume cycle, before s2ram the refcount is 1.
> 
> > I definitely can't see that with the mainline on my machines.
> 
> It is in mainline too.

Does the appended patch help?

Rafael


---
From: Rafael J. Wysocki <[e-mail]>
Subject: cpufreq: Fix cpufreq driver module refcount balance after suspend/resume

Since cpufreq_cpu_put() called by __cpufreq_remove_dev() drops the
driver module refcount, the latter has to bump up that refcount to
start with to balance the drop, or the cpufreq driver refcount will
become negative after a suspend/resume cycle.

Reported-by: Toralf Förster <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>
---
 drivers/cpufreq/cpufreq.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)


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Patch

Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -1016,6 +1016,9 @@  static int __cpufreq_remove_dev(struct d
 
 	pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
 
+	if (!try_module_get(cpufreq_driver->owner))
+		return -EINVAL;
+
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 
 	data = per_cpu(cpufreq_cpu_data, cpu);
@@ -1025,7 +1028,8 @@  static int __cpufreq_remove_dev(struct d
 
 	if (!data) {
 		pr_debug("%s: No cpu_data found\n", __func__);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err;
 	}
 
 	if (cpufreq_driver->target)
@@ -1063,9 +1067,9 @@  static int __cpufreq_remove_dev(struct d
 
 			unlock_policy_rwsem_write(cpu);
 
-			ret = sysfs_create_link(&cpu_dev->kobj, &data->kobj,
+			sysfs_create_link(&cpu_dev->kobj, &data->kobj,
 					"cpufreq");
-			return -EINVAL;
+			goto err;
 		}
 
 		WARN_ON(lock_policy_rwsem_write(cpu));
@@ -1110,6 +1114,10 @@  static int __cpufreq_remove_dev(struct d
 
 	per_cpu(cpufreq_policy_cpu, cpu) = -1;
 	return 0;
+
+ err:
+	module_put(cpufreq_driver->owner);
+	return ret;
 }