[PATCH] tracing: probes: error if BTF is required but unavailable

[Martin Kaiser <martin@kaiser.cx>]

traceprobe_expand_meta_args expands probe arguments based on BTF info.

Return an error if we have arguments that need expanding but BTF is not
supported.

The params variable is now unused, it can be removed.

Fixes: d157d7694460 ("tracing/probes: Support BTF field access from $retval")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---
 kernel/trace/trace_probe.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index cfb710095f65..516c439932a0 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -2287,7 +2287,6 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
 					 int *new_argc, char *buf, int bufsize,
 					 struct traceprobe_parse_context *ctx)
 {
-	const struct btf_param *params = NULL;
 	int i, j, n, used, ret, args_idx = -1;
 	const char **new_argv __free(kfree) = NULL;
 
@@ -2305,7 +2304,7 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
 		if (args_idx != -1) {
 			/* $arg* requires BTF info */
 			trace_probe_log_err(0, NOSUP_BTFARG);
-			return (const char **)params;
+			return ERR_PTR(-EOPNOTSUPP);
 		}
 		*new_argc = argc;
 		return NULL;
-- 
2.43.7