[PATCH] Simplify the registration of clocksources (92c7e002) · Commits · e / devices / android_kernel_oneplus_sm7250

arch/i386/kernel/tsc.c

+1 −2

Original line number	Original line	Diff line number	Diff line
	@@ -323,8 +323,7 @@ static int tsc_update_callback(void)

	/* check to see if we should switch to the safe clocksource: */		/* check to see if we should switch to the safe clocksource: */
	if (clocksource_tsc.rating != 0 && check_tsc_unstable()) {		if (clocksource_tsc.rating != 0 && check_tsc_unstable()) {
	clocksource_tsc.rating = 0;		clocksource_change_rating(&clocksource_tsc, 0);
	clocksource_reselect();
	change = 1;		change = 1;
	}		}

include/linux/clocksource.h

+3 −3

Original line number	Original line	Diff line number	Diff line
	@@ -178,8 +178,8 @@ static inline void clocksource_calculate_interval(struct clocksource *c,


	/* used to install a new clocksource */		/* used to install a new clocksource */
	int clocksource_register(struct clocksource*);		extern int clocksource_register(struct clocksource*);
	void clocksource_reselect(void);		extern struct clocksource* clocksource_get_next(void);
	struct clocksource* clocksource_get_next(void);		extern void clocksource_change_rating(struct clocksource *cs, int rating);

	#endif /* _LINUX_CLOCKSOURCE_H */		#endif /* _LINUX_CLOCKSOURCE_H */

kernel/time/clocksource.c

+58 −62

Original line number	Original line	Diff line number	Diff line
	@@ -48,6 +48,7 @@ extern struct clocksource clocksource_jiffies;
	*/		*/
	static struct clocksource *curr_clocksource = &clocksource_jiffies;		static struct clocksource *curr_clocksource = &clocksource_jiffies;
	static struct clocksource *next_clocksource;		static struct clocksource *next_clocksource;
			static struct clocksource *clocksource_override;
	static LIST_HEAD(clocksource_list);		static LIST_HEAD(clocksource_list);
	static DEFINE_SPINLOCK(clocksource_lock);		static DEFINE_SPINLOCK(clocksource_lock);
	static char override_name[32];		static char override_name[32];
	@@ -84,60 +85,46 @@ struct clocksource *clocksource_get_next(void)
	}		}

	/**		/**
	* select_clocksource - Finds the best registered clocksource.		* select_clocksource - Selects the best registered clocksource.
	*		*
	* Private function. Must hold clocksource_lock when called.		* Private function. Must hold clocksource_lock when called.
	*		*
	* Looks through the list of registered clocksources, returning		* Select the clocksource with the best rating, or the clocksource,
	* the one with the highest rating value. If there is a clocksource		* which is selected by userspace override.
	* name that matches the override string, it returns that clocksource.
	*/		*/
	static struct clocksource *select_clocksource(void)		static struct clocksource *select_clocksource(void)
	{		{
	struct clocksource *best = NULL;		if (list_empty(&clocksource_list))
	struct list_head *tmp;		return NULL;

	list_for_each(tmp, &clocksource_list) {
	struct clocksource *src;

	src = list_entry(tmp, struct clocksource, list);		if (clocksource_override)
	if (!best)		return clocksource_override;
	best = src;

	/* check for override: */
	if (strlen(src->name) == strlen(override_name) &&
	!strcmp(src->name, override_name)) {
	best = src;
	break;
	}
	/* pick the highest rating: */
	if (src->rating > best->rating)
	best = src;
	}

	return best;		return list_entry(clocksource_list.next, struct clocksource, list);
	}		}

	/**		/*
	* is_registered_source - Checks if clocksource is registered		* Enqueue the clocksource sorted by rating
	* @c: pointer to a clocksource
	*
	* Private helper function. Must hold clocksource_lock when called.
	*
	* Returns one if the clocksource is already registered, zero otherwise.
	*/		*/
	static int is_registered_source(struct clocksource *c)		static int clocksource_enqueue(struct clocksource *c)
	{		{
	int len = strlen(c->name);		struct list_head tmp, entry = &clocksource_list;
	struct list_head *tmp;

	list_for_each(tmp, &clocksource_list) {		list_for_each(tmp, &clocksource_list) {
	struct clocksource *src;		struct clocksource *cs;

	src = list_entry(tmp, struct clocksource, list);		cs = list_entry(tmp, struct clocksource, list);
	if (strlen(src->name) == len && !strcmp(src->name, c->name))		if (cs == c)
	return 1;		return -EBUSY;
			/* Keep track of the place, where to insert */
			if (cs->rating >= c->rating)
			entry = tmp;
	}		}
			list_add(&c->list, entry);

			if (strlen(c->name) == strlen(override_name) &&
			!strcmp(c->name, override_name))
			clocksource_override = c;

	return 0;		return 0;
	}		}
	@@ -150,42 +137,32 @@ static int is_registered_source(struct clocksource *c)
	*/		*/
	int clocksource_register(struct clocksource *c)		int clocksource_register(struct clocksource *c)
	{		{
	int ret = 0;
	unsigned long flags;		unsigned long flags;
			int ret = 0;

	spin_lock_irqsave(&clocksource_lock, flags);		spin_lock_irqsave(&clocksource_lock, flags);
	/* check if clocksource is already registered */		ret = clocksource_enqueue(c);
	if (is_registered_source(c)) {		if (!ret)
	printk("register_clocksource: Cannot register %s. "
	"Already registered!", c->name);
	ret = -EBUSY;
	} else {
	/* register it */
	list_add(&c->list, &clocksource_list);
	/* scan the registered clocksources, and pick the best one */
	next_clocksource = select_clocksource();		next_clocksource = select_clocksource();
	}
	spin_unlock_irqrestore(&clocksource_lock, flags);		spin_unlock_irqrestore(&clocksource_lock, flags);
	return ret;		return ret;
	}		}
	EXPORT_SYMBOL(clocksource_register);		EXPORT_SYMBOL(clocksource_register);

	/**		/**
	* clocksource_reselect - Rescan list for next clocksource		* clocksource_change_rating - Change the rating of a registered clocksource
	*		*
	* A quick helper function to be used if a clocksource changes its
	* rating. Forces the clocksource list to be re-scanned for the best
	* clocksource.
	*/		*/
	void clocksource_reselect(void)		void clocksource_change_rating(struct clocksource *cs, int rating)
	{		{
	unsigned long flags;		unsigned long flags;

	spin_lock_irqsave(&clocksource_lock, flags);		spin_lock_irqsave(&clocksource_lock, flags);
			list_del(&cs->list);
			clocksource_enqueue(cs);
	next_clocksource = select_clocksource();		next_clocksource = select_clocksource();
	spin_unlock_irqrestore(&clocksource_lock, flags);		spin_unlock_irqrestore(&clocksource_lock, flags);
	}		}
	EXPORT_SYMBOL(clocksource_reselect);

	#ifdef CONFIG_SYSFS		#ifdef CONFIG_SYSFS
	/**		/**
	@@ -221,7 +198,11 @@ sysfs_show_current_clocksources(struct sys_device dev, char buf)
	static ssize_t sysfs_override_clocksource(struct sys_device *dev,		static ssize_t sysfs_override_clocksource(struct sys_device *dev,
	const char *buf, size_t count)		const char *buf, size_t count)
	{		{
			struct clocksource *ovr = NULL;
			struct list_head *tmp;
	size_t ret = count;		size_t ret = count;
			int len;

	/* strings from sysfs write are not 0 terminated! */		/* strings from sysfs write are not 0 terminated! */
	if (count >= sizeof(override_name))		if (count >= sizeof(override_name))
	return -EINVAL;		return -EINVAL;
	@@ -229,17 +210,32 @@ static ssize_t sysfs_override_clocksource(struct sys_device *dev,
	/* strip of \n: */		/* strip of \n: */
	if (buf[count-1] == '\n')		if (buf[count-1] == '\n')
	count--;		count--;
	if (count < 1)
	return -EINVAL;

	spin_lock_irq(&clocksource_lock);		spin_lock_irq(&clocksource_lock);

	/* copy the name given: */		if (count > 0)
	memcpy(override_name, buf, count);		memcpy(override_name, buf, count);
	override_name[count] = 0;		override_name[count] = 0;

			len = strlen(override_name);
			if (len) {
			ovr = clocksource_override;
	/* try to select it: */		/* try to select it: */
			list_for_each(tmp, &clocksource_list) {
			struct clocksource *cs;

			cs = list_entry(tmp, struct clocksource, list);
			if (strlen(cs->name) == len &&
			!strcmp(cs->name, override_name))
			ovr = cs;
			}
			}

			/* Reselect, when the override name has changed */
			if (ovr != clocksource_override) {
			clocksource_override = ovr;
	next_clocksource = select_clocksource();		next_clocksource = select_clocksource();
			}

	spin_unlock_irq(&clocksource_lock);		spin_unlock_irq(&clocksource_lock);