static struct clocksource *curr_clocksource;
static LIST_HEAD(clocksource_list);
static DEFINE_MUTEX(clocksource_mutex);
-static char override_name[32];
+#define CS_NAME_LEN 32
+static char override_name[CS_NAME_LEN];
static int finished_booting;
#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
static void clocksource_dequeue_watchdog(struct clocksource *cs)
{
- struct clocksource *tmp;
unsigned long flags;
spin_lock_irqsave(&watchdog_lock, flags);
- if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
- /* cs is a watched clocksource. */
- list_del_init(&cs->wd_list);
- } else if (cs == watchdog) {
- /* Reset watchdog cycles */
- clocksource_reset_watchdog();
- /* Current watchdog is removed. Find an alternative. */
- watchdog = NULL;
- list_for_each_entry(tmp, &clocksource_list, list) {
- if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY)
- continue;
- if (!watchdog || tmp->rating > watchdog->rating)
- watchdog = tmp;
+ if (cs != watchdog) {
+ if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
+ /* cs is a watched clocksource. */
+ list_del_init(&cs->wd_list);
+ /* Check if the watchdog timer needs to be stopped. */
+ clocksource_stop_watchdog();
}
}
- cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
- /* Check if the watchdog timer needs to be stopped. */
- clocksource_stop_watchdog();
spin_unlock_irqrestore(&watchdog_lock, flags);
}
return 0;
}
+static bool clocksource_is_watchdog(struct clocksource *cs)
+{
+ return cs == watchdog;
+}
+
#else /* CONFIG_CLOCKSOURCE_WATCHDOG */
static void clocksource_enqueue_watchdog(struct clocksource *cs)
static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
static inline void clocksource_resume_watchdog(void) { }
static inline int clocksource_watchdog_kthread(void *data) { return 0; }
+static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }
#endif /* CONFIG_CLOCKSOURCE_WATCHDOG */
#ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
-/**
- * clocksource_select - Select the best clocksource available
- *
- * Private function. Must hold clocksource_mutex when called.
- *
- * Select the clocksource with the best rating, or the clocksource,
- * which is selected by userspace override.
- */
-static void clocksource_select(void)
+static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur)
{
- struct clocksource *best, *cs;
+ struct clocksource *cs;
if (!finished_booting || list_empty(&clocksource_list))
+ return NULL;
+
+ /*
+ * We pick the clocksource with the highest rating. If oneshot
+ * mode is active, we pick the highres valid clocksource with
+ * the best rating.
+ */
+ list_for_each_entry(cs, &clocksource_list, list) {
+ if (skipcur && cs == curr_clocksource)
+ continue;
+ if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES))
+ continue;
+ return cs;
+ }
+ return NULL;
+}
+
+static void __clocksource_select(bool skipcur)
+{
+ bool oneshot = tick_oneshot_mode_active();
+ struct clocksource *best, *cs;
+
+ /* Find the best suitable clocksource */
+ best = clocksource_find_best(oneshot, skipcur);
+ if (!best)
return;
- /* First clocksource on the list has the best rating. */
- best = list_first_entry(&clocksource_list, struct clocksource, list);
+
/* Check for the override clocksource. */
list_for_each_entry(cs, &clocksource_list, list) {
+ if (skipcur && cs == curr_clocksource)
+ continue;
if (strcmp(cs->name, override_name) != 0)
continue;
/*
* capable clocksource if the tick code is in oneshot
* mode (highres or nohz)
*/
- if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) &&
- tick_oneshot_mode_active()) {
+ if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) {
/* Override clocksource cannot be used. */
printk(KERN_WARNING "Override clocksource %s is not "
"HRT compatible. Cannot switch while in "
best = cs;
break;
}
- if (curr_clocksource != best) {
- printk(KERN_INFO "Switching to clocksource %s\n", best->name);
+
+ if (curr_clocksource != best && !timekeeping_notify(best)) {
+ pr_info("Switched to clocksource %s\n", best->name);
curr_clocksource = best;
- timekeeping_notify(curr_clocksource);
}
}
+/**
+ * clocksource_select - Select the best clocksource available
+ *
+ * Private function. Must hold clocksource_mutex when called.
+ *
+ * Select the clocksource with the best rating, or the clocksource,
+ * which is selected by userspace override.
+ */
+static void clocksource_select(void)
+{
+ return __clocksource_select(false);
+}
+
+static void clocksource_select_fallback(void)
+{
+ return __clocksource_select(true);
+}
+
#else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */
static inline void clocksource_select(void) { }
}
EXPORT_SYMBOL(clocksource_change_rating);
+/*
+ * Unbind clocksource @cs. Called with clocksource_mutex held
+ */
+static int clocksource_unbind(struct clocksource *cs)
+{
+ /*
+ * I really can't convince myself to support this on hardware
+ * designed by lobotomized monkeys.
+ */
+ if (clocksource_is_watchdog(cs))
+ return -EBUSY;
+
+ if (cs == curr_clocksource) {
+ /* Select and try to install a replacement clock source */
+ clocksource_select_fallback();
+ if (curr_clocksource == cs)
+ return -EBUSY;
+ }
+ clocksource_dequeue_watchdog(cs);
+ list_del_init(&cs->list);
+ return 0;
+}
+
/**
* clocksource_unregister - remove a registered clocksource
* @cs: clocksource to be unregistered
*/
-void clocksource_unregister(struct clocksource *cs)
+int clocksource_unregister(struct clocksource *cs)
{
+ int ret = 0;
+
mutex_lock(&clocksource_mutex);
- clocksource_dequeue_watchdog(cs);
- list_del(&cs->list);
- clocksource_select();
+ if (!list_empty(&cs->list))
+ ret = clocksource_unbind(cs);
mutex_unlock(&clocksource_mutex);
+ return ret;
}
EXPORT_SYMBOL(clocksource_unregister);
return count;
}
+static size_t clocksource_get_uname(const char *buf, char *dst, size_t cnt)
+{
+ size_t ret = cnt;
+
+ /* strings from sysfs write are not 0 terminated! */
+ if (!cnt || cnt >= CS_NAME_LEN)
+ return -EINVAL;
+
+ /* strip of \n: */
+ if (buf[cnt-1] == '\n')
+ cnt--;
+ if (cnt > 0)
+ memcpy(dst, buf, cnt);
+ dst[cnt] = 0;
+ return ret;
+}
+
/**
* sysfs_override_clocksource - interface for manually overriding clocksource
* @dev: unused
struct device_attribute *attr,
const char *buf, size_t count)
{
- size_t ret = count;
-
- /* strings from sysfs write are not 0 terminated! */
- if (count >= sizeof(override_name))
- return -EINVAL;
-
- /* strip of \n: */
- if (buf[count-1] == '\n')
- count--;
+ size_t ret;
mutex_lock(&clocksource_mutex);
- if (count > 0)
- memcpy(override_name, buf, count);
- override_name[count] = 0;
- clocksource_select();
+ ret = clocksource_get_uname(buf, override_name, count);
+ if (ret >= 0)
+ clocksource_select();
mutex_unlock(&clocksource_mutex);
return ret;
}
+/**
+ * sysfs_unbind_current_clocksource - interface for manually unbinding clocksource
+ * @dev: unused
+ * @attr: unused
+ * @buf: unused
+ * @count: length of buffer
+ *
+ * Takes input from sysfs interface for manually unbinding a clocksource.
+ */
+static ssize_t sysfs_unbind_clocksource(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct clocksource *cs;
+ char name[CS_NAME_LEN];
+ size_t ret;
+
+ ret = clocksource_get_uname(buf, name, count);
+ if (ret < 0)
+ return ret;
+
+ ret = -ENODEV;
+ mutex_lock(&clocksource_mutex);
+ list_for_each_entry(cs, &clocksource_list, list) {
+ if (strcmp(cs->name, name))
+ continue;
+ ret = clocksource_unbind(cs);
+ break;
+ }
+ mutex_unlock(&clocksource_mutex);
+
+ return ret ? ret : count;
+}
+
/**
* sysfs_show_available_clocksources - sysfs interface for listing clocksource
* @dev: unused
static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources,
sysfs_override_clocksource);
+static DEVICE_ATTR(unbind_clocksource, 0200, NULL, sysfs_unbind_clocksource);
+
static DEVICE_ATTR(available_clocksource, 0444,
sysfs_show_available_clocksources, NULL);
error = device_create_file(
&device_clocksource,
&dev_attr_current_clocksource);
+ if (!error)
+ error = device_create_file(&device_clocksource,
+ &dev_attr_unbind_clocksource);
if (!error)
error = device_create_file(
&device_clocksource,
projects / mirror_ubuntu-bionic-kernel.git / blobdiff