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From:   Josh Poimboeuf <jpoimboe@kernel.org>
To:     x86@kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Miroslav Benes <mbenes@suse.cz>
Subject: [PATCH] objtool: Improve rate-limiting for missing __noreturn warnings
Date:   Thu,  8 Jun 2023 09:23:32 -0700
Message-Id: <185b1a78b42776467929ce9e7851e4dbcd0b55d4.1686241345.git.jpoimboe@kernel.org>
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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 <jpoimboe@kernel.org>
---
 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