Commit 172da89e authored by Vineeth Vijayan's avatar Vineeth Vijayan Committed by Heiko Carstens
Browse files

s390/cio: avoid excessive path-verification requests 



Currently when removing a device from cio_ignore list, we trigger a
path-verification for all the subchannels available in the system. This
could lead to path-verification requests on subchannels with an online
device, which could cause unwanted delay. Instead of all the
subchannels, trigger the path-verifications to those without an online
device.

Reported-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Fixes: 2297791c ("s390/cio: dont unregister subchannel from child-drivers")
Signed-off-by: default avatarVineeth Vijayan <vneethv@linux.ibm.com>
Reviewed-by: default avatarPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 5816b3e6

drivers/s390/cio/blacklist.c

+5 −3
Original line number Diff line number Diff line
@@ -262,10 +262,12 @@ static int blacklist_parse_proc_parameters(char *buf) 


	if (strcmp("free", parm) == 0) {

		rc = blacklist_parse_parameters(buf, free, 0);

		/* There could be subchannels without proper devices connected.

		 * evaluate all the entries

		/*

		 * Evaluate the subchannels without an online device. This way,

		 * no path-verification will be triggered on those subchannels

		 * and it avoids unnecessary delays.

		 */

		css_schedule_eval_all();

		css_schedule_eval_cond(CSS_EVAL_NOT_ONLINE, 0);

	} else if (strcmp("add", parm) == 0)

		rc = blacklist_parse_parameters(buf, add, 0);

	else if (strcmp("purge", parm) == 0)

drivers/s390/cio/css.c

+31 −9
Original line number Diff line number Diff line
@@ -788,27 +788,49 @@ static int __unset_registered(struct device *dev, void *data) 
	return 0;

}



void css_schedule_eval_all_unreg(unsigned long delay)

static int __unset_online(struct device *dev, void *data)

{

	struct idset *set = data;

	struct subchannel *sch = to_subchannel(dev);

	struct ccw_device *cdev = sch_get_cdev(sch);



	if (cdev && cdev->online)

		idset_sch_del(set, sch->schid);



	return 0;

}



void css_schedule_eval_cond(enum css_eval_cond cond, unsigned long delay)

{

	unsigned long flags;

	struct idset *unreg_set;

	struct idset *set;



	/* Find unregistered subchannels. */

	unreg_set = idset_sch_new();

	if (!unreg_set) {

	set = idset_sch_new();

	if (!set) {

		/* Fallback. */

		css_schedule_eval_all();

		return;

	}

	idset_fill(unreg_set);

	bus_for_each_dev(&css_bus_type, NULL, unreg_set, __unset_registered);

	idset_fill(set);

	switch (cond) {

	case CSS_EVAL_UNREG:

		bus_for_each_dev(&css_bus_type, NULL, set, __unset_registered);

		break;

	case CSS_EVAL_NOT_ONLINE:

		bus_for_each_dev(&css_bus_type, NULL, set, __unset_online);

		break;

	default:

		break;

	}



	/* Apply to slow_subchannel_set. */

	spin_lock_irqsave(&slow_subchannel_lock, flags);

	idset_add_set(slow_subchannel_set, unreg_set);

	idset_add_set(slow_subchannel_set, set);

	atomic_set(&css_eval_scheduled, 1);

	queue_delayed_work(cio_work_q, &slow_path_work, delay);

	spin_unlock_irqrestore(&slow_subchannel_lock, flags);

	idset_free(unreg_set);

	idset_free(set);

}



void css_wait_for_slow_path(void)
@@ -820,7 +842,7 @@ void css_wait_for_slow_path(void) 
void css_schedule_reprobe(void)

{

	/* Schedule with a delay to allow merging of subsequent calls. */

	css_schedule_eval_all_unreg(1 * HZ);

	css_schedule_eval_cond(CSS_EVAL_UNREG, 1 * HZ);

}

EXPORT_SYMBOL_GPL(css_schedule_reprobe);

drivers/s390/cio/css.h

+9 −1
Original line number Diff line number Diff line
@@ -34,6 +34,14 @@ 
#define SNID_STATE3_MULTI_PATH	   1

#define SNID_STATE3_SINGLE_PATH	   0



/*

 * Conditions used to specify which subchannels need evaluation

 */

enum css_eval_cond {

	CSS_EVAL_UNREG,		/* unregistered subchannels */

	CSS_EVAL_NOT_ONLINE	/* sch without an online-device */

};



struct path_state {

	__u8  state1 : 2;	/* path state value 1 */

	__u8  state2 : 2;	/* path state value 2 */
@@ -136,7 +144,7 @@ static inline struct channel_subsystem *css_by_id(u8 cssid) 
/* Helper functions to build lists for the slow path. */

void css_schedule_eval(struct subchannel_id schid);

void css_schedule_eval_all(void);

void css_schedule_eval_all_unreg(unsigned long delay);

void css_schedule_eval_cond(enum css_eval_cond, unsigned long delay);

int css_complete_work(void);



int sch_is_pseudo_sch(struct subchannel *);