Messages in this thread Patch in this message | | | Date | Wed, 11 Oct 2017 09:21:09 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH] tracing/jump-labels: Add message when a trace event has no instances |
| |
On Tue, Oct 10, 2017 at 06:56:30PM -0400, Steven Rostedt wrote:
> +/* Without jump labels we don't know how many instances, just assume one */ > +static inline int static_key_instances(struct static_key *key) > +{ > + return 1; > +}
That's a tad dodgy.. it works for your current usage, but..
> +int static_key_instances(struct static_key *key) > +{ > + return jump_label_update(key, true); > }
That's a bit yuck too :/ But I'm not entirely sure something like the below is actually better...
--- kernel/jump_label.c | 50 ++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 40 insertions(+), 10 deletions(-)
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 0bf2e8f5244a..97286ed6c93d 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -354,9 +354,17 @@ static enum jump_label_type jump_label_type(struct jump_entry *entry) return enabled ^ branch; } -static void __jump_label_update(struct static_key *key, - struct jump_entry *entry, - struct jump_entry *stop) +typedef void (*jump_label_visit_f)(struct jump_entry *entry, void *data); + +void __jump_label_update(struct jump_entry *entry, void *data) +{ + arch_jump_label_transform(entry, jump_label_type(entry)); +} + +static void +__jump_label_visit(struct static_key *key, struct jump_entry *entry, + struct jump_entry *stop, jump_label_visit_f *visit, + void *data) { for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { /* @@ -365,7 +373,7 @@ static void __jump_label_update(struct static_key *key, * init code, see jump_label_invalidate_module_init(). */ if (entry->code && kernel_text_address(entry->code)) - arch_jump_label_transform(entry, jump_label_type(entry)); + visit(entry, data); } } @@ -470,7 +478,8 @@ static int __jump_label_mod_text_reserved(void *start, void *end) start, end); } -static void __jump_label_mod_update(struct static_key *key) +static void +__jump_label_mod_visit(struct static_key *key, jump_label_visit_f visit, void *data) { struct static_key_mod *mod; @@ -490,7 +499,8 @@ static void __jump_label_mod_update(struct static_key *key) stop = __stop___jump_table; else stop = m->jump_entries + m->num_jump_entries; - __jump_label_update(key, mod->entries, stop); + + __jump_label_visit(key, mod->entries, stop, visit, data); } } @@ -571,7 +581,7 @@ static int jump_label_add_module(struct module *mod) /* Only update if we've changed from our initial state */ if (jump_label_type(iter) != jump_label_init_type(iter)) - __jump_label_update(key, iter, iter_stop); + __jump_label_visit(key, iter, iter_stop, __jump_label_update, NULL); } return 0; @@ -711,7 +721,7 @@ int jump_label_text_reserved(void *start, void *end) return ret; } -static void jump_label_update(struct static_key *key) +static void jump_label_visit(struct static_key *key, jump_label_visit_f visit, void *data) { struct jump_entry *stop = __stop___jump_table; struct jump_entry *entry; @@ -719,7 +729,7 @@ static void jump_label_update(struct static_key *key) struct module *mod; if (static_key_linked(key)) { - __jump_label_mod_update(key); + __jump_label_mod_visit(key, visit, data); return; } @@ -732,7 +742,27 @@ static void jump_label_update(struct static_key *key) entry = static_key_entries(key); /* if there are no users, entry can be NULL */ if (entry) - __jump_label_update(key, entry, stop); + __jump_label_visit(key, entry, stop, visit, data); +} + +static void jump_label_update(struct static_key *key) +{ + jump_label_visit(key, __jump_label_update, NULL); +} + +static void __jump_label_count(struct jump_entry *entry, void *data) +{ + unsigned int *count = data; + count++; +} + +unsigned int static_key_instances(struct static_key *key) +{ + unsigned int count = 0; + + jump_label_visit(key, __jump_label_count, &count); + + return count; } #ifdef CONFIG_STATIC_KEYS_SELFTEST
| |