[PATCH 3.10 46/58] clockevents: Add module refcount

Greg Kroah-Hartman
2013-12-06T22:03:39Z

From: Thomas Gleixner <tglx@linutronix.de>

commit ccf33d6880f39a35158fff66db13000ae4943fac upstream.

We want to be able to remove clockevent modules as well. Add a
refcount so we don't remove a module with an active clock event
device.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.307435149@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kim Phillips <kim.phillips@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/clockchips.h | 3 +++
kernel/time/clockevents.c | 1 +
kernel/time/tick-broadcast.c | 3 +++
kernel/time/tick-common.c | 4 ++++
4 files changed, 11 insertions(+)

--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -30,6 +30,7 @@ enum clock_event_nofitiers {
#include <linux/notifier.h>

struct clock_event_device;
+struct module;

/* Clock event mode commands */
enum clock_event_mode {
@@ -83,6 +84,7 @@ enum clock_event_mode {
* @irq: IRQ number (only for non CPU local devices)
* @cpumask: cpumask to indicate for which CPUs this device works
* @list: list head for the management code
+ * @owner: module reference
*/
struct clock_event_device {
void (*event_handler)(struct clock_event_device *);
@@ -112,6 +114,7 @@ struct clock_event_device {
int irq;
const struct cpumask *cpumask;
struct list_head list;
+ struct module *owner;
} ____cacheline_aligned;

/*
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -392,6 +392,7 @@ void clockevents_exchange_device(struct
* released list and do a notify add later.
*/
if (old) {
+ module_put(old->owner);
clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
list_del(&old->list);
list_add(&old->list, &clockevents_released);
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -19,6 +19,7 @@
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/smp.h>
+#include <linux/module.h>

#include "tick-internal.h"

@@ -74,6 +75,8 @@ void tick_install_broadcast_device(struc
tick_broadcast_device.evtdev->rating >= dev->rating) ||
(dev->features & CLOCK_EVT_FEAT_C3STOP))
return;
+ if (!try_module_get(dev->owner))
+ return;

clockevents_exchange_device(tick_broadcast_device.evtdev, dev);
if (cur)
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -18,6 +18,7 @@
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/sched.h>
+#include <linux/module.h>

#include <asm/irq_regs.h>

@@ -261,6 +262,9 @@ void tick_check_new_device(struct clock_
goto out_bc;
}

+ if (!try_module_get(newdev->owner))
+ return;
+
/*
* Replace the eventually existing device by the new
* device. If the current device is the broadcast device, do