Re: [PATCH v7 07/10] tracing: add and use genericset_trigger_filter() implementation

[Steven Rostedt]

On Tue, 27 Aug 2013 14:40:19 -0500
Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx> wrote:
 
>  enum {
>  	FILTER_OTHER = 0,
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index 326ba32..6c701c3 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -412,13 +412,15 @@ static inline notrace int ftrace_get_offsets_##call(			\
>   *	struct ftrace_data_offsets_<call> __maybe_unused __data_offsets;
>   *	struct ring_buffer_event *event;
>   *	struct ftrace_raw_<call> *entry; <-- defined in stage 1
> + *	enum event_trigger_type __tt = ETT_NONE;
>   *	struct ring_buffer *buffer;
>   *	unsigned long irq_flags;
>   *	int __data_size;
>   *	int pc;
>   *
> - *	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
> - *		     &ftrace_file->flags))
> + *	if ((ftrace_file->flags & (FTRACE_EVENT_FL_SOFT_DISABLED |
> + *	     FTRACE_EVENT_FL_TRIGGER_MODE)) ==
> + *	    FTRACE_EVENT_FL_SOFT_DISABLED)

Don't worry too much about 80 character limit here. Move the
FL_SOFT_DISABLED up.

>   *		return;
>   *
>   *	local_save_flags(irq_flags);
> @@ -437,9 +439,19 @@ static inline notrace int ftrace_get_offsets_##call(			\
>   *	{ <assign>; }  <-- Here we assign the entries by the __field and
>   *			   __array macros.
>   *
> - *	if (!filter_current_check_discard(buffer, event_call, entry, event))
> - *		trace_nowake_buffer_unlock_commit(buffer,
> - *						   event, irq_flags, pc);
> + *	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> + *		     &ftrace_file->flags))
> + *		__tt = event_triggers_call(ftrace_file, entry);
> + *
> + *	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
> + *		     &ftrace_file->flags))
> + *		ring_buffer_discard_commit(buffer, event);
> + *	else if (!filter_current_check_discard(buffer, event_call,
> + *					       entry, event))
> + *		trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
> + *
> + *	if (__tt)
> + *		event_triggers_post_call(ftrace_file, __tt);
>   * }
>   *
>   * static struct trace_event ftrace_event_type_<call> = {
> @@ -521,17 +533,15 @@ ftrace_raw_event_##call(void *__data, proto)				\
>  	struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
>  	struct ring_buffer_event *event;				\
>  	struct ftrace_raw_##call *entry;				\
> +	enum event_trigger_type __tt = ETT_NONE;			\
>  	struct ring_buffer *buffer;					\
>  	unsigned long irq_flags;					\
>  	int __data_size;						\
>  	int pc;								\
>  									\
> -	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,			\
> -		     &ftrace_file->flags))				\
> -		event_triggers_call(ftrace_file);			\
> -									\
> -	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,			\
> -		     &ftrace_file->flags))				\
> +	if ((ftrace_file->flags & (FTRACE_EVENT_FL_SOFT_DISABLED |	\
> +	     FTRACE_EVENT_FL_TRIGGER_MODE)) ==				\
> +	    FTRACE_EVENT_FL_SOFT_DISABLED)				\

Ditto.

Also, I don't think we need to worry about the flags changing, so we
should be able to just save it.

	unsigned long eflags = ftrace_file_flags;

And then we can also only delay the event triggers if it has a
condition. What about adding a FTRACE_EVENT_FL_TRIGGER_COND_BIT, and do:

	if (!(eflags & FTRACE_EVENT_FL_TRIGGER_COND))
		if (eflags & FTRACE_EVENT_FL_TRIGGER_MODE)
			event_triggers_call(ftrace_file, NULL);

		if (eflags & FTRACE_EVENT_FL_SOFT_DISABLED)
			return;
	}

>  		return;							\
>  									\
>  	local_save_flags(irq_flags);					\
> @@ -551,8 +561,19 @@ ftrace_raw_event_##call(void *__data, proto)				\
>  									\
>  	{ assign; }							\
>  									\
> -	if (!filter_current_check_discard(buffer, event_call, entry, event)) \
> +	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,			\
> +		     &ftrace_file->flags))				\
> +		__tt = event_triggers_call(ftrace_file, entry);		\

Then here we test just the TRIGGER_COND bit.


> +									\
> +	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,                 \
> +		     &ftrace_file->flags))                              \
> +		ring_buffer_discard_commit(buffer, event);              \
> +	else if (!filter_current_check_discard(buffer, event_call,      \
> +					       entry, event))		\
>  		trace_buffer_unlock_commit(buffer, event, irq_flags, pc); \
> +									\
> +	if (__tt)							\
> +		event_triggers_post_call(ftrace_file, __tt);		\

This part is fine.

>  }
>  /*
>   * The ftrace_test_probe is compiled out, it is only here as a build time check
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 3cb846e..af5f3b6 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -994,6 +994,10 @@ extern int apply_subsystem_event_filter(struct ftrace_subsystem_dir *dir,
>  extern void print_subsystem_event_filter(struct event_subsystem *system,
>  					 struct trace_seq *s);
>  extern int filter_assign_type(const char *type);
> +extern int create_event_filter(struct ftrace_event_call *call,
> +			       char *filter_str, bool set_str,
> +			       struct event_filter **filterp);
> +extern void free_event_filter(struct event_filter *filter);
>  
>  struct ftrace_event_field *
>  trace_find_event_field(struct ftrace_event_call *call, char *name);
> diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
> index 97daa8c..0c45aa1 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -781,6 +781,11 @@ static void __free_filter(struct event_filter *filter)
>  	kfree(filter);
>  }
>  
> +void free_event_filter(struct event_filter *filter)
> +{
> +	__free_filter(filter);
> +}
> +
>  /*
>   * Called when destroying the ftrace_event_call.
>   * The call is being freed, so we do not need to worry about
> @@ -1806,6 +1811,14 @@ static int create_filter(struct ftrace_event_call *call,
>  	return err;
>  }
>  
> +int create_event_filter(struct ftrace_event_call *call,
> +			char *filter_str, bool set_str,
> +			struct event_filter **filterp)
> +{
> +	return create_filter(call, filter_str, set_str, filterp);
> +}
> +
> +
>  /**
>   * create_system_filter - create a filter for an event_subsystem
>   * @system: event_subsystem to create a filter for
> diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
> index 54678e2..b5e7ca7 100644
> --- a/kernel/trace/trace_events_trigger.c
> +++ b/kernel/trace/trace_events_trigger.c
> @@ -43,24 +43,53 @@ struct event_trigger_data {
>  static void
>  trigger_data_free(struct event_trigger_data *data)
>  {
> +	if (data->cmd_ops->set_filter)
> +		data->cmd_ops->set_filter(NULL, data, NULL);
> +
>  	synchronize_sched(); /* make sure current triggers exit before free */
>  	kfree(data);
>  }
>  
> -void event_triggers_call(struct ftrace_event_file *file)
> +enum event_trigger_type
> +event_triggers_call(struct ftrace_event_file *file, void *rec)
>  {
>  	struct event_trigger_data *data;
> +	enum event_trigger_type tt = ETT_NONE;
>  
>  	if (list_empty(&file->triggers))
> -		return;
> +		return tt;
>  
>  	preempt_disable_notrace();
> -	list_for_each_entry_rcu(data, &file->triggers, list)
> +	list_for_each_entry_rcu(data, &file->triggers, list) {
> +		if (data->filter && !filter_match_preds(data->filter, rec))

We would need a check for !rec, just to be safe (with the mods I talked
about).

> +			continue;
> +		if (data->cmd_ops->post_trigger) {
> +			tt |= data->cmd_ops->trigger_type;
> +			continue;
> +		}
>  		data->ops->func((void **)&data);
> +	}
>  	preempt_enable_notrace();
> +
> +	return tt;
>  }
>  EXPORT_SYMBOL_GPL(event_triggers_call);
>  
> +void
> +event_triggers_post_call(struct ftrace_event_file *file,
> +			 enum event_trigger_type tt)
> +{
> +	struct event_trigger_data *data;
> +
> +	preempt_disable_notrace();
> +	list_for_each_entry_rcu(data, &file->triggers, list) {
> +		if (data->cmd_ops->trigger_type & tt)
> +			data->ops->func((void **)&data);
> +	}
> +	preempt_enable_notrace();
> +}
> +EXPORT_SYMBOL_GPL(event_triggers_post_call);
> +
>  static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
>  {
>  	struct ftrace_event_file *event_file = event_file_data(m->private);
> @@ -561,6 +590,66 @@ event_trigger_callback(struct event_command *cmd_ops,
>  	goto out;
>  }
>  
> +/**
> + * set_trigger_filter - generic event_command @set_filter
> + * implementation
> + *
> + * Common implementation for event command filter parsing and filter
> + * instantiation.
> + *
> + * Usually used directly as the @set_filter method in event command
> + * implementations.
> + *
> + * Also used to remove a filter (if filter_str = NULL).
> + */
> +static int set_trigger_filter(char *filter_str, void *trigger_data,
> +			      struct ftrace_event_file *file)
> +{
> +	struct event_trigger_data *data = trigger_data;
> +	struct event_filter *filter = NULL, *tmp;
> +	int ret = -EINVAL;
> +	char *s;
> +
> +	if (!filter_str) /* clear the current filter */
> +		goto assign;
> +
> +	s = strsep(&filter_str, " \t");
> +
> +	if (!strlen(s) || strcmp(s, "if") != 0)
> +		goto out;
> +
> +	if (!filter_str)
> +		goto out;
> +
> +	/* The filter is for the 'trigger' event, not the triggered event */
> +	ret = create_event_filter(file->event_call, filter_str, false, &filter);
> +	if (ret)
> +		goto out;
> + assign:
> +	tmp = data->filter;
> +
> +	rcu_assign_pointer(data->filter, filter);
> +
> +	if (tmp) {
> +		/* Make sure the call is done with the filter */
> +		synchronize_sched();
> +		free_event_filter(tmp);
> +	}
> +
> +	kfree(data->filter_str);
> +
> +	if (filter_str) {
> +		data->filter_str = kstrdup(filter_str, GFP_KERNEL);
> +		if (!data->filter_str) {
> +			free_event_filter(data->filter);
> +			data->filter = NULL;
> +			ret = -ENOMEM;
> +		}
> +	}
> + out:
> +	return ret;
> +}
> +
>  static void
>  traceon_trigger(void **_data)
>  {
> @@ -698,6 +787,7 @@ static struct event_command trigger_traceon_cmd = {
>  	.reg			= register_trigger,
>  	.unreg			= unregister_trigger,
>  	.get_trigger_ops	= onoff_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
>  };
>  
>  static struct event_command trigger_traceoff_cmd = {
> @@ -707,6 +797,7 @@ static struct event_command trigger_traceoff_cmd = {
>  	.reg			= register_trigger,
>  	.unreg			= unregister_trigger,
>  	.get_trigger_ops	= onoff_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
>  };
>  
>  static void
> @@ -788,6 +879,7 @@ static struct event_command trigger_snapshot_cmd = {
>  	.reg			= register_snapshot_trigger,
>  	.unreg			= unregister_trigger,
>  	.get_trigger_ops	= snapshot_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
>  };
>  
>  /*
> @@ -867,6 +959,7 @@ static struct event_command trigger_stacktrace_cmd = {
>  	.reg			= register_trigger,
>  	.unreg			= unregister_trigger,
>  	.get_trigger_ops	= stacktrace_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
>  };
>  
>  static __init void unregister_trigger_traceon_traceoff_cmds(void)
> @@ -1194,6 +1287,7 @@ static struct event_command trigger_enable_cmd = {
>  	.reg			= event_enable_register_trigger,
>  	.unreg			= event_enable_unregister_trigger,
>  	.get_trigger_ops	= event_enable_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
>  };
>  
>  static struct event_command trigger_disable_cmd = {
> @@ -1203,6 +1297,7 @@ static struct event_command trigger_disable_cmd = {
>  	.reg			= event_enable_register_trigger,
>  	.unreg			= event_enable_unregister_trigger,
>  	.get_trigger_ops	= event_enable_get_trigger_ops,
> +	.set_filter		= set_trigger_filter,
>  };
>  
>  static __init void unregister_trigger_enable_disable_cmds(void)
> diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
> index 4f56d54..84cdbce 100644
> --- a/kernel/trace/trace_syscalls.c
> +++ b/kernel/trace/trace_syscalls.c
> @@ -306,6 +306,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
>  	struct syscall_trace_enter *entry;
>  	struct syscall_metadata *sys_data;
>  	struct ring_buffer_event *event;
> +	enum event_trigger_type __tt = ETT_NONE;
>  	struct ring_buffer *buffer;
>  	unsigned long irq_flags;
>  	int pc;
> @@ -321,9 +322,9 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
>  	if (!ftrace_file)
>  		return;
>  
> -	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, &ftrace_file->flags))
> -		event_triggers_call(ftrace_file);
> -	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
> +	if ((ftrace_file->flags &
> +	     (FTRACE_EVENT_FL_SOFT_DISABLED | FTRACE_EVENT_FL_TRIGGER_MODE)) ==
> +	    FTRACE_EVENT_FL_SOFT_DISABLED)

We would need the same changes here too.

-- Steve

>  		return;
>  
>  	sys_data = syscall_nr_to_meta(syscall_nr);
> @@ -345,10 +346,17 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
>  	entry->nr = syscall_nr;
>  	syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
>  
> -	if (!filter_current_check_discard(buffer, sys_data->enter_event,
> -					  entry, event))
> +	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, &ftrace_file->flags))
> +		__tt = event_triggers_call(ftrace_file, entry);
> +
> +	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
> +		ring_buffer_discard_commit(buffer, event);
> +	else if (!filter_current_check_discard(buffer, sys_data->enter_event,
> +					       entry, event))
>  		trace_current_buffer_unlock_commit(buffer, event,
>  						   irq_flags, pc);
> +	if (__tt)
> +		event_triggers_post_call(ftrace_file, __tt);
>  }
>  
>  static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
> @@ -358,6 +366,7 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
>  	struct syscall_trace_exit *entry;
>  	struct syscall_metadata *sys_data;
>  	struct ring_buffer_event *event;
> +	enum event_trigger_type __tt = ETT_NONE;
>  	struct ring_buffer *buffer;
>  	unsigned long irq_flags;
>  	int pc;
> @@ -372,9 +381,9 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
>  	if (!ftrace_file)
>  		return;
>  
> -	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, &ftrace_file->flags))
> -		event_triggers_call(ftrace_file);
> -	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
> +	if ((ftrace_file->flags &
> +	     (FTRACE_EVENT_FL_SOFT_DISABLED | FTRACE_EVENT_FL_TRIGGER_MODE)) ==
> +	    FTRACE_EVENT_FL_SOFT_DISABLED)
>  		return;
>  
>  	sys_data = syscall_nr_to_meta(syscall_nr);
> @@ -395,10 +404,17 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
>  	entry->nr = syscall_nr;
>  	entry->ret = syscall_get_return_value(current, regs);
>  
> -	if (!filter_current_check_discard(buffer, sys_data->exit_event,
> -					  entry, event))
> +	if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, &ftrace_file->flags))
> +		__tt = event_triggers_call(ftrace_file, entry);
> +
> +	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
> +		ring_buffer_discard_commit(buffer, event);
> +	else if (!filter_current_check_discard(buffer, sys_data->exit_event,
> +					       entry, event))
>  		trace_current_buffer_unlock_commit(buffer, event,
>  						   irq_flags, pc);
> +	if (__tt)
> +		event_triggers_post_call(ftrace_file, __tt);
>  }
>  
>  static int reg_event_syscall_enter(struct ftrace_event_file *file,

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/