From 172da89ed0eaf9d9348f5decb86ad04c624b39d1 Mon Sep 17 00:00:00 2001 From: Vineeth Vijayan Date: Fri, 10 Sep 2021 13:45:24 +0200 Subject: 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: Julian Wiedmann Fixes: 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers") Signed-off-by: Vineeth Vijayan Reviewed-by: Peter Oberparleiter Signed-off-by: Heiko Carstens --- drivers/s390/cio/blacklist.c | 8 +++++--- drivers/s390/cio/css.c | 40 +++++++++++++++++++++++++++++++--------- drivers/s390/cio/css.h | 10 +++++++++- 3 files changed, 45 insertions(+), 13 deletions(-) diff --git a/drivers/s390/cio/blacklist.c b/drivers/s390/cio/blacklist.c index f3c656975e05..93695d535380 100644 --- a/drivers/s390/cio/blacklist.c +++ b/drivers/s390/cio/blacklist.c @@ -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) diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 3377097e65de..44461928aab8 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -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); diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h index c98522cbe276..ede0b905bc6f 100644 --- a/drivers/s390/cio/css.h +++ b/drivers/s390/cio/css.h @@ -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 *); -- cgit v1.2.3