tracing/filter: Swap entire filter of events
When creating a new filter, instead of allocating the filter to the event call first and then processing the filter, it is easier to process a temporary filter and then just swap it with the call filter. By doing this, it simplifies the code. A filter is allocated and processed, when it is done, it is swapped with the call filter, synchronize_sched() is called to make sure all callers are done with the old filter (filters are called with premption disabled), and then the old filter is freed. Cc: Tom Zanussi <tzanussi@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
Steven Rostedt
Родитель
bf93f9ed3a
Коммит
75b8e98263
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@ -425,10 +425,15 @@ int filter_match_preds(struct event_filter *filter, void *rec)
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struct filter_pred *preds;
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struct filter_pred *pred;
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struct filter_pred *root;
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int n_preds = ACCESS_ONCE(filter->n_preds);
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int n_preds;
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int done = 0;
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/* no filter is considered a match */
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if (!filter)
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return 1;
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n_preds = filter->n_preds;
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if (!n_preds)
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return 1;
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@ -509,6 +514,9 @@ static void parse_error(struct filter_parse_state *ps, int err, int pos)
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static void remove_filter_string(struct event_filter *filter)
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{
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if (!filter)
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return;
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kfree(filter->filter_string);
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filter->filter_string = NULL;
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}
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@ -568,9 +576,10 @@ static void append_filter_err(struct filter_parse_state *ps,
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void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
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{
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struct event_filter *filter = call->filter;
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struct event_filter *filter;
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mutex_lock(&event_mutex);
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filter = call->filter;
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if (filter && filter->filter_string)
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trace_seq_printf(s, "%s\n", filter->filter_string);
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else
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@ -581,9 +590,10 @@ void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
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void print_subsystem_event_filter(struct event_subsystem *system,
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struct trace_seq *s)
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{
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struct event_filter *filter = system->filter;
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struct event_filter *filter;
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mutex_lock(&event_mutex);
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filter = system->filter;
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if (filter && filter->filter_string)
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trace_seq_printf(s, "%s\n", filter->filter_string);
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else
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@ -745,26 +755,9 @@ static void __free_preds(struct event_filter *filter)
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filter->n_preds = 0;
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}
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static void reset_preds(struct event_filter *filter)
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static void filter_disable(struct ftrace_event_call *call)
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{
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int n_preds = filter->n_preds;
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int i;
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filter->n_preds = 0;
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filter->root = NULL;
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if (!filter->preds)
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return;
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for (i = 0; i < n_preds; i++)
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filter->preds[i].fn = filter_pred_none;
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}
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static void filter_disable_preds(struct ftrace_event_call *call)
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{
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struct event_filter *filter = call->filter;
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call->flags &= ~TRACE_EVENT_FL_FILTERED;
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reset_preds(filter);
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}
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static void __free_filter(struct event_filter *filter)
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@ -777,11 +770,16 @@ static void __free_filter(struct event_filter *filter)
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kfree(filter);
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}
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/*
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* Called when destroying the ftrace_event_call.
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* The call is being freed, so we do not need to worry about
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* the call being currently used. This is for module code removing
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* the tracepoints from within it.
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*/
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void destroy_preds(struct ftrace_event_call *call)
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{
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__free_filter(call->filter);
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call->filter = NULL;
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call->flags &= ~TRACE_EVENT_FL_FILTERED;
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}
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static struct event_filter *__alloc_filter(void)
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@ -789,11 +787,6 @@ static struct event_filter *__alloc_filter(void)
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struct event_filter *filter;
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filter = kzalloc(sizeof(*filter), GFP_KERNEL);
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if (!filter)
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return ERR_PTR(-ENOMEM);
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filter->n_preds = 0;
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return filter;
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}
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@ -838,36 +831,6 @@ static int __alloc_preds(struct event_filter *filter, int n_preds)
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return 0;
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}
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static int init_filter(struct ftrace_event_call *call)
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{
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if (call->filter)
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return 0;
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call->flags &= ~TRACE_EVENT_FL_FILTERED;
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call->filter = __alloc_filter();
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if (IS_ERR(call->filter))
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return PTR_ERR(call->filter);
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return 0;
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}
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static int init_subsystem_preds(struct event_subsystem *system)
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{
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struct ftrace_event_call *call;
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int err;
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list_for_each_entry(call, &ftrace_events, list) {
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if (strcmp(call->class->system, system->name) != 0)
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continue;
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err = init_filter(call);
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if (err)
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return err;
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}
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return 0;
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}
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static void filter_free_subsystem_preds(struct event_subsystem *system)
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{
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struct ftrace_event_call *call;
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@ -876,11 +839,23 @@ static void filter_free_subsystem_preds(struct event_subsystem *system)
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if (strcmp(call->class->system, system->name) != 0)
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continue;
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filter_disable_preds(call);
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filter_disable(call);
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remove_filter_string(call->filter);
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}
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}
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static void filter_free_subsystem_filters(struct event_subsystem *system)
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{
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struct ftrace_event_call *call;
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list_for_each_entry(call, &ftrace_events, list) {
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if (strcmp(call->class->system, system->name) != 0)
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continue;
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__free_filter(call->filter);
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call->filter = NULL;
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}
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}
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static int filter_add_pred_fn(struct filter_parse_state *ps,
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struct ftrace_event_call *call,
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struct event_filter *filter,
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@ -1743,88 +1718,129 @@ fail:
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return err;
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}
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struct filter_list {
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struct list_head list;
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struct event_filter *filter;
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};
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static int replace_system_preds(struct event_subsystem *system,
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struct filter_parse_state *ps,
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char *filter_string)
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{
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struct ftrace_event_call *call;
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struct filter_list *filter_item;
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struct filter_list *tmp;
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LIST_HEAD(filter_list);
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bool fail = true;
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int err;
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list_for_each_entry(call, &ftrace_events, list) {
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struct event_filter *filter = call->filter;
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if (strcmp(call->class->system, system->name) != 0)
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continue;
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/* try to see if the filter can be applied */
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err = replace_preds(call, filter, ps, filter_string, true);
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/*
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* Try to see if the filter can be applied
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* (filter arg is ignored on dry_run)
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*/
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err = replace_preds(call, NULL, ps, filter_string, true);
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if (err)
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goto fail;
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}
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/* set all filter pred counts to zero */
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list_for_each_entry(call, &ftrace_events, list) {
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struct event_filter *filter = call->filter;
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struct event_filter *filter;
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if (strcmp(call->class->system, system->name) != 0)
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continue;
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reset_preds(filter);
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}
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filter_item = kzalloc(sizeof(*filter_item), GFP_KERNEL);
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if (!filter_item)
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goto fail_mem;
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/*
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* Since some of the preds may be used under preemption
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* we need to wait for them to finish before we may
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* reallocate them.
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*/
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synchronize_sched();
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list_add_tail(&filter_item->list, &filter_list);
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list_for_each_entry(call, &ftrace_events, list) {
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struct event_filter *filter = call->filter;
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filter_item->filter = __alloc_filter();
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if (!filter_item->filter)
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goto fail_mem;
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filter = filter_item->filter;
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if (strcmp(call->class->system, system->name) != 0)
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continue;
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/* really apply the filter */
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filter_disable_preds(call);
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err = replace_preds(call, filter, ps, filter_string, false);
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/* Can only fail on no memory */
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err = replace_filter_string(filter, filter_string);
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if (err)
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filter_disable_preds(call);
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else {
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goto fail_mem;
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err = replace_preds(call, filter, ps, filter_string, false);
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if (err) {
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filter_disable(call);
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parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
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append_filter_err(ps, filter);
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} else
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call->flags |= TRACE_EVENT_FL_FILTERED;
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replace_filter_string(filter, filter_string);
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}
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/*
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* Regardless of if this returned an error, we still
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* replace the filter for the call.
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*/
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filter = call->filter;
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call->filter = filter_item->filter;
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filter_item->filter = filter;
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fail = false;
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}
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if (fail)
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goto fail;
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/*
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* The calls can still be using the old filters.
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* Do a synchronize_sched() to ensure all calls are
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* done with them before we free them.
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*/
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synchronize_sched();
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list_for_each_entry_safe(filter_item, tmp, &filter_list, list) {
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__free_filter(filter_item->filter);
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list_del(&filter_item->list);
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kfree(filter_item);
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}
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return 0;
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fail:
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/* No call succeeded */
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list_for_each_entry_safe(filter_item, tmp, &filter_list, list) {
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list_del(&filter_item->list);
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kfree(filter_item);
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}
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parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
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return -EINVAL;
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fail_mem:
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/* If any call succeeded, we still need to sync */
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if (!fail)
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synchronize_sched();
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list_for_each_entry_safe(filter_item, tmp, &filter_list, list) {
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__free_filter(filter_item->filter);
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list_del(&filter_item->list);
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kfree(filter_item);
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}
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return -ENOMEM;
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}
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int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
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{
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int err;
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struct filter_parse_state *ps;
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struct event_filter *filter;
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struct event_filter *tmp;
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int err = 0;
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mutex_lock(&event_mutex);
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err = init_filter(call);
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if (err)
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goto out_unlock;
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if (!strcmp(strstrip(filter_string), "0")) {
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filter_disable_preds(call);
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reset_preds(call->filter);
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filter_disable(call);
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filter = call->filter;
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if (!filter)
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goto out_unlock;
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call->filter = NULL;
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/* Make sure the filter is not being used */
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synchronize_sched();
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__free_preds(call->filter);
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remove_filter_string(call->filter);
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__free_filter(filter);
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goto out_unlock;
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}
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@ -1833,29 +1849,41 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
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if (!ps)
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goto out_unlock;
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filter_disable_preds(call);
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replace_filter_string(call->filter, filter_string);
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filter = __alloc_filter();
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if (!filter) {
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kfree(ps);
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goto out_unlock;
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}
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replace_filter_string(filter, filter_string);
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parse_init(ps, filter_ops, filter_string);
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err = filter_parse(ps);
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if (err) {
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append_filter_err(ps, call->filter);
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append_filter_err(ps, filter);
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goto out;
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}
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/*
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* Make sure all the pred counts are zero so that
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* no task is using it when we reallocate the preds array.
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*/
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reset_preds(call->filter);
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synchronize_sched();
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err = replace_preds(call, call->filter, ps, filter_string, false);
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if (err)
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append_filter_err(ps, call->filter);
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else
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err = replace_preds(call, filter, ps, filter_string, false);
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if (err) {
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filter_disable(call);
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append_filter_err(ps, filter);
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} else
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call->flags |= TRACE_EVENT_FL_FILTERED;
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out:
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/*
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* Always swap the call filter with the new filter
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* even if there was an error. If there was an error
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* in the filter, we disable the filter and show the error
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* string
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*/
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tmp = call->filter;
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call->filter = filter;
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if (tmp) {
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/* Make sure the call is done with the filter */
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synchronize_sched();
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__free_filter(tmp);
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}
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filter_opstack_clear(ps);
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postfix_clear(ps);
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kfree(ps);
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@ -1868,18 +1896,21 @@ out_unlock:
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int apply_subsystem_event_filter(struct event_subsystem *system,
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char *filter_string)
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{
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int err;
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struct filter_parse_state *ps;
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struct event_filter *filter;
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int err = 0;
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mutex_lock(&event_mutex);
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err = init_subsystem_preds(system);
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if (err)
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goto out_unlock;
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if (!strcmp(strstrip(filter_string), "0")) {
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filter_free_subsystem_preds(system);
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remove_filter_string(system->filter);
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filter = system->filter;
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system->filter = NULL;
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/* Ensure all filters are no longer used */
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synchronize_sched();
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filter_free_subsystem_filters(system);
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__free_filter(filter);
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goto out_unlock;
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}
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@ -1888,7 +1919,17 @@ int apply_subsystem_event_filter(struct event_subsystem *system,
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if (!ps)
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goto out_unlock;
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replace_filter_string(system->filter, filter_string);
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filter = __alloc_filter();
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if (!filter)
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goto out;
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replace_filter_string(filter, filter_string);
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/*
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* No event actually uses the system filter
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* we can free it without synchronize_sched().
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*/
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__free_filter(system->filter);
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system->filter = filter;
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parse_init(ps, filter_ops, filter_string);
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err = filter_parse(ps);
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@ -1945,7 +1986,7 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id,
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goto out_unlock;
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filter = __alloc_filter();
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if (IS_ERR(filter)) {
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if (!filter) {
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err = PTR_ERR(filter);
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goto out_unlock;
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}
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