tracing: Add 'snapshot' event trigger command
Add 'snapshot' event_command. snapshot event triggers are added by the user via this command in a similar way and using practically the same syntax as the analogous 'snapshot' ftrace function command, but instead of writing to the set_ftrace_filter file, the snapshot event trigger is written to the per-event 'trigger' files: echo 'snapshot' > .../somesys/someevent/trigger The above command will turn on snapshots for someevent i.e. whenever someevent is hit, a snapshot will be done. This also adds a 'count' version that limits the number of times the command will be invoked: echo 'snapshot:N' > .../somesys/someevent/trigger Where N is the number of times the command will be invoked. The above command will snapshot N times for someevent i.e. whenever someevent is hit N times, a snapshot will be done. Also adds a new tracing_alloc_snapshot() function - the existing tracing_snapshot_alloc() function is a special version of tracing_snapshot() that also does the snapshot allocation - the snapshot triggers would like to be able to do just the allocation but not take a snapshot; the existing tracing_snapshot_alloc() in turn now also calls tracing_alloc_snapshot() underneath to do that allocation. Link: http://lkml.kernel.org/r/c9524dd07ce01f9dcbd59011290e0a8d5b47d7ad.1382622043.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> [ fix up from kbuild test robot <fengguang.wu@intel.com report ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -346,6 +346,7 @@ struct ftrace_event_file {
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enum event_trigger_type {
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enum event_trigger_type {
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ETT_NONE = (0),
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ETT_NONE = (0),
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ETT_TRACE_ONOFF = (1 << 0),
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ETT_TRACE_ONOFF = (1 << 0),
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ETT_SNAPSHOT = (1 << 1),
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};
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};
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extern void destroy_preds(struct ftrace_event_file *file);
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extern void destroy_preds(struct ftrace_event_file *file);
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@ -594,6 +594,28 @@ void free_snapshot(struct trace_array *tr)
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tr->allocated_snapshot = false;
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tr->allocated_snapshot = false;
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}
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}
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/**
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* tracing_alloc_snapshot - allocate snapshot buffer.
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*
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* This only allocates the snapshot buffer if it isn't already
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* allocated - it doesn't also take a snapshot.
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*
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* This is meant to be used in cases where the snapshot buffer needs
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* to be set up for events that can't sleep but need to be able to
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* trigger a snapshot.
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*/
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int tracing_alloc_snapshot(void)
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{
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struct trace_array *tr = &global_trace;
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int ret;
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ret = alloc_snapshot(tr);
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WARN_ON(ret < 0);
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return ret;
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}
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EXPORT_SYMBOL_GPL(tracing_alloc_snapshot);
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/**
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/**
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* trace_snapshot_alloc - allocate and take a snapshot of the current buffer.
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* trace_snapshot_alloc - allocate and take a snapshot of the current buffer.
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*
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*
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@ -607,11 +629,10 @@ void free_snapshot(struct trace_array *tr)
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*/
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*/
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void tracing_snapshot_alloc(void)
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void tracing_snapshot_alloc(void)
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{
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{
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struct trace_array *tr = &global_trace;
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int ret;
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int ret;
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ret = alloc_snapshot(tr);
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ret = tracing_alloc_snapshot();
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if (WARN_ON(ret < 0))
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if (ret < 0)
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return;
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return;
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tracing_snapshot();
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tracing_snapshot();
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@ -623,6 +644,12 @@ void tracing_snapshot(void)
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WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
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WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
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}
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}
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EXPORT_SYMBOL_GPL(tracing_snapshot);
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EXPORT_SYMBOL_GPL(tracing_snapshot);
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int tracing_alloc_snapshot(void)
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{
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WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used");
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return -ENODEV;
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}
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EXPORT_SYMBOL_GPL(tracing_alloc_snapshot);
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void tracing_snapshot_alloc(void)
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void tracing_snapshot_alloc(void)
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{
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{
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/* Give warning */
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/* Give warning */
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@ -1211,6 +1211,7 @@ struct event_command {
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extern int trace_event_enable_disable(struct ftrace_event_file *file,
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extern int trace_event_enable_disable(struct ftrace_event_file *file,
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int enable, int soft_disable);
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int enable, int soft_disable);
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extern int tracing_alloc_snapshot(void);
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extern const char *__start___trace_bprintk_fmt[];
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extern const char *__start___trace_bprintk_fmt[];
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extern const char *__stop___trace_bprintk_fmt[];
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extern const char *__stop___trace_bprintk_fmt[];
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@ -696,6 +696,90 @@ static struct event_command trigger_traceoff_cmd = {
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.get_trigger_ops = onoff_get_trigger_ops,
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.get_trigger_ops = onoff_get_trigger_ops,
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};
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};
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#ifdef CONFIG_TRACER_SNAPSHOT
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static void
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snapshot_trigger(struct event_trigger_data *data)
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{
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tracing_snapshot();
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}
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static void
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snapshot_count_trigger(struct event_trigger_data *data)
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{
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if (!data->count)
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return;
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if (data->count != -1)
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(data->count)--;
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snapshot_trigger(data);
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}
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static int
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register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
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struct event_trigger_data *data,
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struct ftrace_event_file *file)
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{
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int ret = register_trigger(glob, ops, data, file);
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if (ret > 0 && tracing_alloc_snapshot() != 0) {
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unregister_trigger(glob, ops, data, file);
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ret = 0;
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}
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return ret;
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}
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static int
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snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
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struct event_trigger_data *data)
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{
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return event_trigger_print("snapshot", m, (void *)data->count,
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data->filter_str);
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}
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static struct event_trigger_ops snapshot_trigger_ops = {
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.func = snapshot_trigger,
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.print = snapshot_trigger_print,
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.init = event_trigger_init,
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.free = event_trigger_free,
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};
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static struct event_trigger_ops snapshot_count_trigger_ops = {
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.func = snapshot_count_trigger,
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.print = snapshot_trigger_print,
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.init = event_trigger_init,
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.free = event_trigger_free,
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};
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static struct event_trigger_ops *
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snapshot_get_trigger_ops(char *cmd, char *param)
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{
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return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
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}
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static struct event_command trigger_snapshot_cmd = {
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.name = "snapshot",
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.trigger_type = ETT_SNAPSHOT,
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.func = event_trigger_callback,
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.reg = register_snapshot_trigger,
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.unreg = unregister_trigger,
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.get_trigger_ops = snapshot_get_trigger_ops,
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};
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static __init int register_trigger_snapshot_cmd(void)
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{
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int ret;
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ret = register_event_command(&trigger_snapshot_cmd);
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WARN_ON(ret < 0);
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return ret;
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}
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#else
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static __init int register_trigger_snapshot_cmd(void) { return 0; }
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#endif /* CONFIG_TRACER_SNAPSHOT */
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static __init void unregister_trigger_traceon_traceoff_cmds(void)
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static __init void unregister_trigger_traceon_traceoff_cmds(void)
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{
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{
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unregister_event_command(&trigger_traceon_cmd);
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unregister_event_command(&trigger_traceon_cmd);
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@ -719,6 +803,7 @@ static __init int register_trigger_traceon_traceoff_cmds(void)
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__init int register_trigger_cmds(void)
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__init int register_trigger_cmds(void)
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{
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{
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register_trigger_traceon_traceoff_cmds();
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register_trigger_traceon_traceoff_cmds();
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register_trigger_snapshot_cmd();
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return 0;
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return 0;
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}
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}
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