From: "Steven Rostedt (VMware)" 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: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- 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