[PATCH v2 1/3] perf expr: Return -EINVAL for syntax error in expr__find_ids()

[Leo Yan]

expr__find_ids() propagates the parser return value directly.  For syntax
errors, the parser can return a positive value, but callers treat it as
success, e.g., for below case on Arm64 platform:

  metric expr 100 * (STALL_SLOT_BACKEND / (CPU_CYCLES * #slots) - BR_MIS_PRED * 3 / CPU_CYCLES) for backend_bound
  parsing metric: 100 * (STALL_SLOT_BACKEND / (CPU_CYCLES * #slots) - BR_MIS_PRED * 3 / CPU_CYCLES)
  Failure to read '#slots' literal: #slots = nan
  syntax error

Convert positive parser returns in expr__find_ids() to -EINVAL, as a
result, the error value will be respected by callers.

Before:

  perf stat -C 5
  Failure to read '#slots'Failure to read '#slots'Failure to read '#slots'Failure to read '#slots'Segmentation fault

After:

  perf stat -C 5
  Failure to read '#slots'Cannot find metric or group `Default'

Fixes: ded80bda8bc9 ("perf expr: Migrate expr ids table to a hashmap")
Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
---
 tools/perf/util/expr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 465fe2e9bbbeff52d3eebfe71aec53f1e5709991..b7664cb68554b284c2b64ca750bdfb114fa5515e 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -376,7 +376,8 @@ int expr__find_ids(const char *expr, const char *one,
 	if (one)
 		expr__del_id(ctx, one);
 
-	return ret;
+	/* A positive value means syntax error, convert to -EINVAL */
+	return ret > 0 ? -EINVAL : ret;
 }
 
 double expr_id_data__value(const struct expr_id_data *data)

-- 
2.34.1