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Date:   Wed,  9 Nov 2022 02:41:55 +0000
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Message-ID: <20221109024155.2810410-1-connoro@google.com>
Subject: [PATCH bpf-next] bpf: btf: don't log ignored BTF mismatches
From:   "Connor O'Brien" <connoro@google.com>
To:     bpf@vger.kernel.org
Cc:     Martin KaFai Lau <martin.lau@linux.dev>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        linux-kernel@vger.kernel.org, "Connor O'Brien" <connoro@google.com>
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Precedence: bulk

Enabling CONFIG_MODULE_ALLOW_BTF_MISMATCH is an indication that BTF
mismatches are expected and module loading should proceed
anyway. Logging with pr_warn() on every one of these "benign"
mismatches creates unnecessary noise when many such modules are
loaded. Instead, limit logging to the case where a BTF mismatch
actually prevents a module form loading.

Signed-off-by: Connor O'Brien <connoro@google.com>
---
 kernel/bpf/btf.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 5579ff3a5b54..406370487413 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7190,11 +7190,12 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op,
 		}
 		btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size);
 		if (IS_ERR(btf)) {
-			pr_warn("failed to validate module [%s] BTF: %ld\n",
-				mod->name, PTR_ERR(btf));
 			kfree(btf_mod);
-			if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
+			if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
+				pr_warn("failed to validate module [%s] BTF: %ld\n",
+					mod->name, PTR_ERR(btf));
 				err = PTR_ERR(btf);
+			}
 			goto out;
 		}
 		err = btf_alloc_id(btf);
-- 
2.38.1.431.g37b22c650d-goog