2023-06-08 16:33:48

by Josh Poimboeuf

Subject: [PATCH] objtool: Improve rate-limiting for missing __noreturn warnings

If a function with a lot of call sites is missing __noreturn, it could
result in a lot of duplicate warnings (one for each call site).

Each call site's function is already rate-limited to one warning per
function via WARN_INSN(). Do the same for the callee (the "missing
__noreturn" function itself).

Signed-off-by: Josh Poimboeuf <[email protected]>
---
tools/objtool/check.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8936a05f0e5a..bb2ed34cb90e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4507,9 +4507,13 @@ static int validate_reachable_instructions(struct objtool_file *file)
if (prev_insn && prev_insn->dead_end) {
call_dest = insn_call_dest(prev_insn);
if (call_dest && !ignore_noreturn_call(prev_insn)) {
- WARN_INSN(insn, "%s() is missing a __noreturn annotation",
- call_dest->name);
- warnings++;
+ if (!call_dest->warned) {
+ WARN_INSN(insn, "%s() is missing a __noreturn annotation",
+ call_dest->name);
+ warnings++;
+ call_dest->warned = 1;
+ }
+
continue;
}
}
--
2.40.1

2023-06-08 21:19:18

by Josh Poimboeuf

Subject: Re: [PATCH] objtool: Improve rate-limiting for missing __noreturn warnings

On Thu, Jun 08, 2023 at 09:23:32AM -0700, Josh Poimboeuf wrote:
> If a function with a lot of call sites is missing __noreturn, it could
> result in a lot of duplicate warnings (one for each call site).
>
> Each call site's function is already rate-limited to one warning per
> function via WARN_INSN(). Do the same for the callee (the "missing
> __noreturn" function itself).
>
> Signed-off-by: Josh Poimboeuf <[email protected]>
> ---
> tools/objtool/check.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 8936a05f0e5a..bb2ed34cb90e 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -4507,9 +4507,13 @@ static int validate_reachable_instructions(struct objtool_file *file)
> if (prev_insn && prev_insn->dead_end) {
> call_dest = insn_call_dest(prev_insn);
> if (call_dest && !ignore_noreturn_call(prev_insn)) {
> - WARN_INSN(insn, "%s() is missing a __noreturn annotation",
> - call_dest->name);
> - warnings++;
> + if (!call_dest->warned) {
> + WARN_INSN(insn, "%s() is missing a __noreturn annotation",
> + call_dest->name);
> + warnings++;
> + call_dest->warned = 1;
> + }
> +

NAK - this spits out a bunch of unreachables, will need to tweak it a
bit.

--
Josh