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Sat, 12 Apr 2025 18:42:51 -0700 (PDT) Received: from localhost.localdomain ([43.129.244.20]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b02a0de7e21sm7014785a12.21.2025.04.12.18.42.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Apr 2025 18:42:50 -0700 (PDT) From: Menglong Dong X-Google-Original-From: Menglong Dong To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mark.rutland@arm.com, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Menglong Dong Subject: [PATCH bpf v2] ftrace: fix incorrect hash size in register_ftrace_direct() Date: Sun, 13 Apr 2025 09:44:44 +0800 Message-Id: <20250413014444.36724-1-dongml2@chinatelecom.cn> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The maximum of the ftrace hash bits is made fls(32) in register_ftrace_direct(), which seems illogical. So, we fix it by making the max hash bits FTRACE_HASH_MAX_BITS instead. Fixes: d05cb470663a ("ftrace: Fix modification of direct_function hash whil= e in use") Signed-off-by: Menglong Dong Acked-by: Masami Hiramatsu (Google) --- v2: - thanks for Steven's advice, we fix the problem by making the max hash bits FTRACE_HASH_MAX_BITS instead. --- kernel/trace/ftrace.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 1a48aedb5255..d153ad13e0e0 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5914,9 +5914,10 @@ int register_ftrace_direct(struct ftrace_ops *ops, u= nsigned long addr) =20 /* Make a copy hash to place the new and the old entries in */ size =3D hash->count + direct_functions->count; - if (size > 32) - size =3D 32; - new_hash =3D alloc_ftrace_hash(fls(size)); + size =3D fls(size); + if (size > FTRACE_HASH_MAX_BITS) + size =3D FTRACE_HASH_MAX_BITS; + new_hash =3D alloc_ftrace_hash(size); if (!new_hash) goto out_unlock; =20 --=20 2.39.5