tracing/probes: Avoid using params uninitialized in parse_btf_arg()

After a recent change in clang to strengthen uninitialized warnings [1],
it points out that in one of the error paths in parse_btf_arg(), params
is used uninitialized:

  kernel/trace/trace_probe.c:660:19: warning: variable 'params' is uninitialized when used here [-Wuninitialized]
    660 |                         return PTR_ERR(params);
        |                                        ^~~~~~

Match many other NO_BTF_ENTRY error cases and return -ENOENT, clearing
up the warning.

Link: https://lore.kernel.org/all/20250715-trace_probe-fix-const-uninit-warning-v1-1-98960f91dd04@kernel.org/
Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/2110
Fixes: d157d7694460 ("tracing/probes: Support BTF field access from $retval")
Link: https://github.com/llvm/llvm-project/commit/2464313eef01c5b1edf0eccf57a32cdee01472c7
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 424751cdf31f9f10aa9ca6464be05879320db42d..40830a3ecd96c01a6dc68e35450b5d97fb32568e 100644 (file)
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -657,7 +657,7 @@ static int parse_btf_arg(char *varname,
                ret = query_btf_context(ctx);
                if (ret < 0 || ctx->nr_params == 0) {
                        trace_probe_log_err(ctx->offset, NO_BTF_ENTRY);
-                       return PTR_ERR(params);
+                       return -ENOENT;
                }
        }
        params = ctx->params;