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Commit 478325f1 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing: Clean up and document pred_funcs_##type creation and use 



The pred_funcs_##type arrays consist of five functions that are assigned
based on the ops. The array must be in the same order of the ops each
function represents. The PRED_FUNC_START macro denotes the op enum that
starts the op that maps to the pred_funcs_##type arrays. This is all very
subtle and prone to bugs if the code is changed.

Add comments describing how PRED_FUNC_START and pred_funcs_##type array is
used, and also a PRED_FUNC_MAX that is the maximum number of functions in
the arrays.

Clean up select_comparison_fn() that assigns the predicates to the
pred_funcs_##type array function as well as add protection in case an op is
passed in that does not map correctly to the array.

Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent e9baef0d

kernel/trace/trace_events_filter.c

+32 −14
Original line number Diff line number Diff line
@@ -65,6 +65,13 @@ struct filter_op { 


static struct filter_op filter_ops[] = { OPS };



/*

 * pred functions are OP_LT, OP_LE, OP_GT, OP_GE, and OP_BAND

 * pred_funcs_##type below must match the order of them above.

 */

#define PRED_FUNC_START			OP_LT

#define PRED_FUNC_MAX			(OP_BAND - PRED_FUNC_START)



#define ERRORS								\

	C( NONE,	 	"No error"),				\

	C( INVALID_OP,		"Invalid operator"),			\
@@ -172,8 +179,6 @@ static const filter_pred_fn_t pred_funcs_##type[] = { \ 
	filter_pred_BAND_##type,					\

};



#define PRED_FUNC_START			OP_LT



#define DEFINE_EQUALITY_PRED(size)					\

static int filter_pred_##size(struct filter_pred *pred, void *event)	\

{									\
@@ -946,39 +951,52 @@ static filter_pred_fn_t select_comparison_fn(enum filter_op_ids op, 
					    int field_size, int field_is_signed)

{

	filter_pred_fn_t fn = NULL;

	int pred_func_index = -1;



	switch (op) {

	case OP_EQ:

	case OP_NE:

		break;

	default:

		if (WARN_ON_ONCE(op < PRED_FUNC_START))

			return NULL;

		pred_func_index = op - PRED_FUNC_START;

		if (WARN_ON_ONCE(pred_func_index > PRED_FUNC_MAX))

			return NULL;

	}



	switch (field_size) {

	case 8:

		if (op == OP_EQ || op == OP_NE)

		if (pred_func_index < 0)

			fn = filter_pred_64;

		else if (field_is_signed)

			fn = pred_funcs_s64[op - PRED_FUNC_START];

			fn = pred_funcs_s64[pred_func_index];

		else

			fn = pred_funcs_u64[op - PRED_FUNC_START];

			fn = pred_funcs_u64[pred_func_index];

		break;

	case 4:

		if (op == OP_EQ || op == OP_NE)

		if (pred_func_index < 0)

			fn = filter_pred_32;

		else if (field_is_signed)

			fn = pred_funcs_s32[op - PRED_FUNC_START];

			fn = pred_funcs_s32[pred_func_index];

		else

			fn = pred_funcs_u32[op - PRED_FUNC_START];

			fn = pred_funcs_u32[pred_func_index];

		break;

	case 2:

		if (op == OP_EQ || op == OP_NE)

		if (pred_func_index < 0)

			fn = filter_pred_16;

		else if (field_is_signed)

			fn = pred_funcs_s16[op - PRED_FUNC_START];

			fn = pred_funcs_s16[pred_func_index];

		else

			fn = pred_funcs_u16[op - PRED_FUNC_START];

			fn = pred_funcs_u16[pred_func_index];

		break;

	case 1:

		if (op == OP_EQ || op == OP_NE)

		if (pred_func_index < 0)

			fn = filter_pred_8;

		else if (field_is_signed)

			fn = pred_funcs_s8[op - PRED_FUNC_START];

			fn = pred_funcs_s8[pred_func_index];

		else

			fn = pred_funcs_u8[op - PRED_FUNC_START];

			fn = pred_funcs_u8[pred_func_index];

		break;

	}