tracing/probe: Add trace_event_file access APIs for trace_probe
Add trace_event_file access APIs for trace_probe data structure. This simplifies enabling/disabling operations in uprobe and kprobe events so that those don't touch deep inside the trace_probe. This also removing a redundant synchronization when the kprobe event is used from perf, since the perf itself uses tracepoint_synchronize_unregister() after disabling (ftrace- defined) event, thus we don't have to synchronize in that path. Also we don't need to identify local trace_kprobe too anymore. Link: http://lkml.kernel.org/r/155931584587.28323.372301976283354629.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>alistair/sunxi64-5.4-dsi
Masami Hiramatsu
Steven Rostedt (VMware)
parent
46e5376d40
commit
b5f935ee13
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@ -290,34 +290,27 @@ static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
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static int
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enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
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{
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struct event_file_link *link;
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bool enabled = trace_probe_is_enabled(&tk->tp);
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int ret = 0;
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if (file) {
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link = kmalloc(sizeof(*link), GFP_KERNEL);
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if (!link) {
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ret = -ENOMEM;
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goto out;
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}
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link->file = file;
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list_add_tail_rcu(&link->list, &tk->tp.files);
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tk->tp.flags |= TP_FLAG_TRACE;
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ret = __enable_trace_kprobe(tk);
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if (ret) {
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list_del_rcu(&link->list);
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kfree(link);
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tk->tp.flags &= ~TP_FLAG_TRACE;
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}
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} else {
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tk->tp.flags |= TP_FLAG_PROFILE;
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ret = __enable_trace_kprobe(tk);
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ret = trace_probe_add_file(&tk->tp, file);
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if (ret)
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return ret;
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} else
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tk->tp.flags |= TP_FLAG_PROFILE;
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if (enabled)
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return 0;
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ret = __enable_trace_kprobe(tk);
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if (ret) {
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if (file)
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trace_probe_remove_file(&tk->tp, file);
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else
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tk->tp.flags &= ~TP_FLAG_PROFILE;
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}
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out:
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return ret;
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}
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@ -328,54 +321,34 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
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static int
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disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
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{
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struct event_file_link *link = NULL;
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int wait = 0;
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struct trace_probe *tp = &tk->tp;
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int ret = 0;
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if (file) {
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link = find_event_file_link(&tk->tp, file);
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if (!link) {
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ret = -EINVAL;
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if (!trace_probe_get_file_link(tp, file))
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return -ENOENT;
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if (!trace_probe_has_single_file(tp))
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goto out;
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}
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list_del_rcu(&link->list);
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wait = 1;
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if (!list_empty(&tk->tp.files))
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goto out;
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tk->tp.flags &= ~TP_FLAG_TRACE;
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tp->flags &= ~TP_FLAG_TRACE;
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} else
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tk->tp.flags &= ~TP_FLAG_PROFILE;
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tp->flags &= ~TP_FLAG_PROFILE;
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if (!trace_probe_is_enabled(&tk->tp) && trace_probe_is_registered(&tk->tp)) {
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if (!trace_probe_is_enabled(tp) && trace_probe_is_registered(tp)) {
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if (trace_kprobe_is_return(tk))
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disable_kretprobe(&tk->rp);
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else
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disable_kprobe(&tk->rp.kp);
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wait = 1;
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}
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/*
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* if tk is not added to any list, it must be a local trace_kprobe
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* created with perf_event_open. We don't need to wait for these
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* trace_kprobes
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*/
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if (list_empty(&tk->devent.list))
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wait = 0;
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out:
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if (wait) {
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if (file)
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/*
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* Synchronize with kprobe_trace_func/kretprobe_trace_func
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* to ensure disabled (all running handlers are finished).
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* This is not only for kfree(), but also the caller,
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* trace_remove_event_call() supposes it for releasing
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* event_call related objects, which will be accessed in
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* the kprobe_trace_func/kretprobe_trace_func.
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* Synchronization is done in below function. For perf event,
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* file == NULL and perf_trace_event_unreg() calls
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* tracepoint_synchronize_unregister() to ensure synchronize
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* event. We don't need to care about it.
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*/
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synchronize_rcu();
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kfree(link); /* Ignored if link == NULL */
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}
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trace_probe_remove_file(tp, file);
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return ret;
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}
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@ -1044,7 +1017,7 @@ kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
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{
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struct event_file_link *link;
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list_for_each_entry_rcu(link, &tk->tp.files, list)
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trace_probe_for_each_link_rcu(link, &tk->tp)
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__kprobe_trace_func(tk, regs, link->file);
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}
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NOKPROBE_SYMBOL(kprobe_trace_func);
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@ -1094,7 +1067,7 @@ kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
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{
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struct event_file_link *link;
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list_for_each_entry_rcu(link, &tk->tp.files, list)
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trace_probe_for_each_link_rcu(link, &tk->tp)
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__kretprobe_trace_func(tk, ri, regs, link->file);
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}
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NOKPROBE_SYMBOL(kretprobe_trace_func);
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@ -936,3 +936,50 @@ int trace_probe_register_event_call(struct trace_probe *tp)
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return ret;
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}
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int trace_probe_add_file(struct trace_probe *tp, struct trace_event_file *file)
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{
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struct event_file_link *link;
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link = kmalloc(sizeof(*link), GFP_KERNEL);
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if (!link)
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return -ENOMEM;
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link->file = file;
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INIT_LIST_HEAD(&link->list);
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list_add_tail_rcu(&link->list, &tp->files);
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tp->flags |= TP_FLAG_TRACE;
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return 0;
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}
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struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
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struct trace_event_file *file)
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{
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struct event_file_link *link;
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trace_probe_for_each_link(link, tp) {
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if (link->file == file)
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return link;
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}
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return NULL;
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}
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int trace_probe_remove_file(struct trace_probe *tp,
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struct trace_event_file *file)
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{
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struct event_file_link *link;
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link = trace_probe_get_file_link(tp, file);
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if (!link)
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return -ENOENT;
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list_del_rcu(&link->list);
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synchronize_rcu();
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kfree(link);
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if (list_empty(&tp->files))
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tp->flags &= ~TP_FLAG_TRACE;
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return 0;
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}
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@ -248,16 +248,32 @@ static inline bool trace_probe_is_registered(struct trace_probe *tp)
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return !!(tp->flags & TP_FLAG_REGISTERED);
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}
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int trace_probe_init(struct trace_probe *tp, const char *event,
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const char *group);
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void trace_probe_cleanup(struct trace_probe *tp);
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int trace_probe_register_event_call(struct trace_probe *tp);
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static inline int trace_probe_unregister_event_call(struct trace_probe *tp)
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{
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/* tp->event is unregistered in trace_remove_event_call() */
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return trace_remove_event_call(&tp->call);
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}
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static inline bool trace_probe_has_single_file(struct trace_probe *tp)
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{
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return !!list_is_singular(&tp->files);
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}
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int trace_probe_init(struct trace_probe *tp, const char *event,
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const char *group);
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void trace_probe_cleanup(struct trace_probe *tp);
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int trace_probe_register_event_call(struct trace_probe *tp);
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int trace_probe_add_file(struct trace_probe *tp, struct trace_event_file *file);
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int trace_probe_remove_file(struct trace_probe *tp,
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struct trace_event_file *file);
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struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
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struct trace_event_file *file);
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#define trace_probe_for_each_link(pos, tp) \
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list_for_each_entry(pos, &(tp)->files, list)
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#define trace_probe_for_each_link_rcu(pos, tp) \
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list_for_each_entry_rcu(pos, &(tp)->files, list)
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/* Check the name is good for event/group/fields */
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static inline bool is_good_name(const char *name)
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{
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@ -270,18 +286,6 @@ static inline bool is_good_name(const char *name)
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return true;
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}
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static inline struct event_file_link *
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find_event_file_link(struct trace_probe *tp, struct trace_event_file *file)
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{
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struct event_file_link *link;
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list_for_each_entry(link, &tp->files, list)
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if (link->file == file)
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return link;
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return NULL;
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}
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#define TPARG_FL_RETURN BIT(0)
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#define TPARG_FL_KERNEL BIT(1)
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#define TPARG_FL_FENTRY BIT(2)
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@ -863,7 +863,7 @@ static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
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return 0;
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rcu_read_lock();
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list_for_each_entry_rcu(link, &tu->tp.files, list)
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trace_probe_for_each_link_rcu(link, &tu->tp)
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__uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
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rcu_read_unlock();
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@ -877,7 +877,7 @@ static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
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struct event_file_link *link;
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rcu_read_lock();
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list_for_each_entry_rcu(link, &tu->tp.files, list)
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trace_probe_for_each_link_rcu(link, &tu->tp)
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__uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
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rcu_read_unlock();
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}
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@ -924,21 +924,15 @@ probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file,
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filter_func_t filter)
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{
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bool enabled = trace_probe_is_enabled(&tu->tp);
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struct event_file_link *link = NULL;
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int ret;
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if (file) {
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if (tu->tp.flags & TP_FLAG_PROFILE)
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return -EINTR;
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link = kmalloc(sizeof(*link), GFP_KERNEL);
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if (!link)
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return -ENOMEM;
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link->file = file;
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list_add_tail_rcu(&link->list, &tu->tp.files);
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tu->tp.flags |= TP_FLAG_TRACE;
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ret = trace_probe_add_file(&tu->tp, file);
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if (ret < 0)
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return ret;
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} else {
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if (tu->tp.flags & TP_FLAG_TRACE)
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return -EINTR;
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@ -973,13 +967,11 @@ probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file,
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uprobe_buffer_disable();
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err_flags:
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if (file) {
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list_del(&link->list);
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kfree(link);
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tu->tp.flags &= ~TP_FLAG_TRACE;
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} else {
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if (file)
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trace_probe_remove_file(&tu->tp, file);
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else
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tu->tp.flags &= ~TP_FLAG_PROFILE;
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}
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return ret;
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}
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@ -990,26 +982,18 @@ probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
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return;
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if (file) {
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struct event_file_link *link;
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link = find_event_file_link(&tu->tp, file);
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if (!link)
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if (trace_probe_remove_file(&tu->tp, file) < 0)
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return;
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list_del_rcu(&link->list);
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/* synchronize with u{,ret}probe_trace_func */
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synchronize_rcu();
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kfree(link);
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if (!list_empty(&tu->tp.files))
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if (trace_probe_is_enabled(&tu->tp))
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return;
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}
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} else
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tu->tp.flags &= ~TP_FLAG_PROFILE;
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WARN_ON(!uprobe_filter_is_empty(&tu->filter));
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uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
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tu->inode = NULL;
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tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
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uprobe_buffer_disable();
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}
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