On Fri, 09 Mar 2018 21:34:44 -0500
Steven Rostedt <rost...@goodmis.org> wrote:
> From: "Steven Rostedt (VMware)" <rost...@goodmis.org>
>
> 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.
>
This looks good to me.
Reviewed-by: Masami Hiramatsu <mhira...@kernel.org>
Thanks,
> Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
> ---
> kernel/trace/trace_events_filter.c | 46
> ++++++++++++++++++++++++++------------
> 1 file changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/trace/trace_events_filter.c
> b/kernel/trace/trace_events_filter.c
> index a2ef393b3bb2..9d383f4383dc 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -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;
> }
>
> --
> 2.15.1
>
>
--
Masami Hiramatsu <mhira...@kernel.org>
