diff options
| -rw-r--r-- | kernel/trace/trace_events_filter.c | 186 |
1 files changed, 138 insertions, 48 deletions
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 2048560264bb..711520081741 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1335,22 +1335,139 @@ static void filter_free_subsystem_preds(struct trace_subsystem_dir *dir, } } +struct filter_list { + struct list_head list; + struct event_filter *filter; +}; + +struct filter_head { + struct list_head list; + struct rcu_head rcu; +}; + + +static void free_filter_list(struct rcu_head *rhp) +{ + struct filter_head *filter_list = container_of(rhp, struct filter_head, rcu); + struct filter_list *filter_item, *tmp; + + list_for_each_entry_safe(filter_item, tmp, &filter_list->list, list) { + __free_filter(filter_item->filter); + list_del(&filter_item->list); + kfree(filter_item); + } + kfree(filter_list); +} + +static void free_filter_list_tasks(struct rcu_head *rhp) +{ + call_rcu(rhp, free_filter_list); +} + +/* + * The tracepoint_synchronize_unregister() is a double rcu call. + * It calls synchronize_rcu_tasks_trace() followed by synchronize_rcu(). + * Instead of waiting for it, simply call these via the call_rcu*() + * variants. + */ +static void delay_free_filter(struct filter_head *head) +{ + call_rcu_tasks_trace(&head->rcu, free_filter_list_tasks); +} + +static void try_delay_free_filter(struct event_filter *filter) +{ + struct filter_head *head; + struct filter_list *item; + + head = kmalloc(sizeof(*head), GFP_KERNEL); + if (!head) + goto free_now; + + INIT_LIST_HEAD(&head->list); + + item = kmalloc(sizeof(*item), GFP_KERNEL); + if (!item) { + kfree(head); + goto free_now; + } + + item->filter = filter; + list_add_tail(&item->list, &head->list); + delay_free_filter(head); + return; + + free_now: + /* Make sure the filter is not being used */ + tracepoint_synchronize_unregister(); + __free_filter(filter); +} + static inline void __free_subsystem_filter(struct trace_event_file *file) { __free_filter(file->filter); file->filter = NULL; } +static inline void event_set_filter(struct trace_event_file *file, + struct event_filter *filter) +{ + rcu_assign_pointer(file->filter, filter); +} + +static inline void event_clear_filter(struct trace_event_file *file) +{ + RCU_INIT_POINTER(file->filter, NULL); +} + static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir, - struct trace_array *tr) + struct trace_array *tr, + struct event_filter *filter) { struct trace_event_file *file; + struct filter_head *head; + struct filter_list *item; + + head = kmalloc(sizeof(*head), GFP_KERNEL); + if (!head) + goto free_now; + + INIT_LIST_HEAD(&head->list); + + item = kmalloc(sizeof(*item), GFP_KERNEL); + if (!item) { + kfree(head); + goto free_now; + } + + item->filter = filter; + list_add_tail(&item->list, &head->list); list_for_each_entry(file, &tr->events, list) { if (file->system != dir) continue; - __free_subsystem_filter(file); + item = kmalloc(sizeof(*item), GFP_KERNEL); + if (!item) + goto free_now; + item->filter = event_filter(file); + list_add_tail(&item->list, &head->list); + event_clear_filter(file); } + + delay_free_filter(head); + return; + free_now: + tracepoint_synchronize_unregister(); + + if (head) + free_filter_list(&head->rcu); + + list_for_each_entry(file, &tr->events, list) { + if (file->system != dir || !file->filter) + continue; + __free_filter(file->filter); + } + __free_filter(filter); } int filter_assign_type(const char *type) @@ -2120,22 +2237,6 @@ static inline void event_set_filtered_flag(struct trace_event_file *file) trace_buffered_event_enable(); } -static inline void event_set_filter(struct trace_event_file *file, - struct event_filter *filter) -{ - rcu_assign_pointer(file->filter, filter); -} - -static inline void event_clear_filter(struct trace_event_file *file) -{ - RCU_INIT_POINTER(file->filter, NULL); -} - -struct filter_list { - struct list_head list; - struct event_filter *filter; -}; - static int process_system_preds(struct trace_subsystem_dir *dir, struct trace_array *tr, struct filter_parse_error *pe, @@ -2144,11 +2245,16 @@ static int process_system_preds(struct trace_subsystem_dir *dir, struct trace_event_file *file; struct filter_list *filter_item; struct event_filter *filter = NULL; - struct filter_list *tmp; - LIST_HEAD(filter_list); + struct filter_head *filter_list; bool fail = true; int err; + filter_list = kmalloc(sizeof(*filter_list), GFP_KERNEL); + if (!filter_list) + return -ENOMEM; + + INIT_LIST_HEAD(&filter_list->list); + list_for_each_entry(file, &tr->events, list) { if (file->system != dir) @@ -2175,7 +2281,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir, if (!filter_item) goto fail_mem; - list_add_tail(&filter_item->list, &filter_list); + list_add_tail(&filter_item->list, &filter_list->list); /* * Regardless of if this returned an error, we still * replace the filter for the call. @@ -2195,31 +2301,22 @@ static int process_system_preds(struct trace_subsystem_dir *dir, * Do a synchronize_rcu() and to ensure all calls are * done with them before we free them. */ - tracepoint_synchronize_unregister(); - list_for_each_entry_safe(filter_item, tmp, &filter_list, list) { - __free_filter(filter_item->filter); - list_del(&filter_item->list); - kfree(filter_item); - } + delay_free_filter(filter_list); return 0; fail: /* No call succeeded */ - list_for_each_entry_safe(filter_item, tmp, &filter_list, list) { - list_del(&filter_item->list); - kfree(filter_item); - } + free_filter_list(&filter_list->rcu); parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0); return -EINVAL; fail_mem: __free_filter(filter); + /* If any call succeeded, we still need to sync */ if (!fail) - tracepoint_synchronize_unregister(); - list_for_each_entry_safe(filter_item, tmp, &filter_list, list) { - __free_filter(filter_item->filter); - list_del(&filter_item->list); - kfree(filter_item); - } + delay_free_filter(filter_list); + else + free_filter_list(&filter_list->rcu); + return -ENOMEM; } @@ -2361,9 +2458,7 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) event_clear_filter(file); - /* Make sure the filter is not being used */ - tracepoint_synchronize_unregister(); - __free_filter(filter); + try_delay_free_filter(filter); return 0; } @@ -2387,11 +2482,8 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) event_set_filter(file, filter); - if (tmp) { - /* Make sure the call is done with the filter */ - tracepoint_synchronize_unregister(); - __free_filter(tmp); - } + if (tmp) + try_delay_free_filter(tmp); } return err; @@ -2417,9 +2509,7 @@ int apply_subsystem_event_filter(struct trace_subsystem_dir *dir, filter = system->filter; system->filter = NULL; /* Ensure all filters are no longer used */ - tracepoint_synchronize_unregister(); - filter_free_subsystem_filters(dir, tr); - __free_filter(filter); + filter_free_subsystem_filters(dir, tr, filter); return 0; } |