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Commit 05ddb25c authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
Browse files

tracing: Add hist trigger comments for variable-related fields 

Add a few comments to help clarify how variable and variable reference
fields are used in the code.

Link: http://lkml.kernel.org/r/ea857ce948531d7bec712bbb0f38360aa1d378ec.1545161087.git.tom.zanussi@linux.intel.com



Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 91220134

kernel/trace/trace_events_hist.c

+36 −0
Original line number Diff line number Diff line
@@ -40,6 +40,16 @@ enum field_op_id { 
	FIELD_OP_UNARY_MINUS,

};



/*

 * A hist_var (histogram variable) contains variable information for

 * hist_fields having the HIST_FIELD_FL_VAR or HIST_FIELD_FL_VAR_REF

 * flag set.  A hist_var has a variable name e.g. ts0, and is

 * associated with a given histogram trigger, as specified by

 * hist_data.  The hist_var idx is the unique index assigned to the

 * variable by the hist trigger's tracing_map.  The idx is what is

 * used to set a variable's value and, by a variable reference, to

 * retrieve it.

 */

struct hist_var {

	char				*name;

	struct hist_trigger_data	*hist_data;
@@ -56,11 +66,29 @@ struct hist_field { 
	const char			*type;

	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];

	struct hist_trigger_data	*hist_data;



	/*

	 * Variable fields contain variable-specific info in var.

	 */

	struct hist_var			var;

	enum field_op_id		operator;

	char				*system;

	char				*event_name;



	/*

	 * The name field is used for EXPR and VAR_REF fields.  VAR

	 * fields contain the variable name in var.name.

	 */

	char				*name;



	/*

	 * When a histogram trigger is hit, if it has any references

	 * to variables, the values of those variables are collected

	 * into a var_ref_vals array by resolve_var_refs().  The

	 * current value of each variable is read from the tracing_map

	 * using the hist field's hist_var.idx and entered into the

	 * var_ref_idx entry i.e. var_ref_vals[var_ref_idx].

	 */

	unsigned int			var_ref_idx;

	bool                            read_once;

};
@@ -365,6 +393,14 @@ struct action_data { 


	union {

		struct {

			/*

			 * When a histogram trigger is hit, the values of any

			 * references to variables, including variables being passed

			 * as parameters to synthetic events, are collected into a

			 * var_ref_vals array.  This var_ref_idx is the index of the

			 * first param in the array to be passed to the synthetic

			 * event invocation.

			 */

			unsigned int		var_ref_idx;

			char			*match_event;

			char			*match_event_system;