From nobody Sun May 24 22:35:58 2026 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BED1D347536 for ; Wed, 20 May 2026 22:00:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779314452; cv=none; b=gJOKNEF7idlvrEO2ryMcgTZAwbtGPzo8bmVENfiJGHNnOnjYIKa0GqyziyayvwV4j4m3RGhWeIBVnGDOj4PnS1BUDfZmKxCiX5fblZWg7lm7zLGtOZ/fjKsg5is3yefhOztScMKsDhX6f8aXJMgCvPh8MYYErqqg/NUFpyW8+WA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779314452; c=relaxed/simple; bh=rqkyqnF6DSfTKl1qX0DNlIqqmmtuoFM1SE9u2aybMW4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=kJe2886pZhQRKvEp6s+oqW+Mz/5mC/Qad7vNFJzOSZWwChMVSyjUCGcjRgjI3iTHr9hGs1dYOsNwooGbpuLc3cVCYmunqMswoqr8FBkAxalg9IbPbUlsUEKtSrGhIbj8UWbBmsQymxqB7oHT6nzKepL0kfRt0CAa9Q4pQEj41pc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Dron7zMi; arc=none smtp.client-ip=209.85.214.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Dron7zMi" Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-2b788a98557so32825375ad.2 for ; Wed, 20 May 2026 15:00:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779314448; x=1779919248; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=M4QHtY5cUcmeH3B0UPkdScUguA0W0qbFF3qRp77bUwo=; b=Dron7zMiPbg4UbFqv9MWZZ7jsWZyb6a20h5mpaPbVyTluwz+2XA3h5hgY49Jn3l45j dmL52dMq0sPyEi/R8pfngislzVSRp8Oc1fFKKE92grXLp+RhnShzEJVzwNuHMzOr+C5t 52ysI9oi3qA6ViLMtygVAZPkZGBHMMxfcN1qTNjLJ2NQ4FB3rDHu7yKiWmJ2geFnQISC VR+h76wQ4Q/7eUA3WHiLX6LpCfjwYqN/9Rk+5WFQIOZwmQ1cTLcDqSjCzz/ogT6QxOKy GYs0Si9A7xfy5qRBrk1uIwTc2uiO/3AYBZRPUJpHgTkU/soMuHcWiSvo650JvFUJ12xP gtDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779314448; x=1779919248; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=M4QHtY5cUcmeH3B0UPkdScUguA0W0qbFF3qRp77bUwo=; b=iVGwqqoMg9fwo0OjGZUw67Ou/VK7SgyVCkUnl9WRfOsUueVn/o1UHfVVM5BVPtI0zz oBLkTRxmbl0dPmL+N5O+/L0SHVwTT1/8syk6rjptat/jNqpuhfNuI60wY5mtGmYZBHns 2hgemSmoWq5YYstgAVE2mG4msVjqYupgyR8U81tZIa3OwWrjhjIk/eVYIbXQbXMta+f+ 41WOSTvTsg87GvcJRW70N8e3U2rMcAKd4ALybV1vpD9S2FWKSaDJysevwuvK0YwcC3F0 TczXBuPVxm4dOMVdbpXtim6APMbZkMxtwqsQxw48FAS7fmnH76TrFRGl5GjfJEmw8REK hC+Q== X-Forwarded-Encrypted: i=1; AFNElJ+eTtH0leuNX/T3ZF5r9OpgsZwlxRj14vP6YAsV7H2SyG4Gp7uD6nPOALn3/sHh/Nug6Sml2UGtbb3tPFw=@vger.kernel.org X-Gm-Message-State: AOJu0YxRpW9ffZWFiQEIs34+HhSkH6wFliJgZ31NdsXYukEkidwAJgIq Sd27arcAqbb4VHZm6N0dHcOPxVmn2F+kpqqq6ctAj22sbDzJ/oJjcqvl X-Gm-Gg: Acq92OGxDVu/OhU6ecxsZOKDYxEk/62iHrLYKm8AnXsx3ZHgjVMcL2w7Pu0JGEYlSXP k3oj1IRUm9ixzcGjL7NZsZIiahwJu7wkYLeWgADbiOIwGkwDl6o7DU78x+lMARxL2Ck/hqWNAOZ IHmf8ol3VnAugiYTUwILAaw/FO4soNwgxWUpcifKGo0u76UrReLSWAdczRUYeyW0gHn8CK/P5Sa A0p2JbH/6gLzXmRjwGJzisVNxw2k6qllO8eQ/zJ5GdMKkZbB5seeH2rEk9qkyLUOvniCeqriDWk oBQi0lpn/NNPSan8VkzH9g7+8ArEPfE9oYgE0nWuh8fiiekV78c5R6EHyzFWdX3cZp6QQO5NLcE B0NTrFtTz2k3FYrNYLSePON31zebA+rh7hbqelsDKI+aeAARZ/llSKY73Ac9pXF9B1rcOYj0OkG 0C+jQCFNUJQi8mkhwV/LfBjfwBgHoNRLE0mNAPd8E10bYu2mNFOsvxLY67SH0BzY1ZGD0DpDYnS nmuHobZjfQYMx9nFSfEA4ILtpZgMXsr2EqcGRZD90eTNw== X-Received: by 2002:a17:90b:5644:b0:35b:e5ce:73bb with SMTP id 98e67ed59e1d1-36a44f0d1d0mr332606a91.1.1779314448276; Wed, 20 May 2026 15:00:48 -0700 (PDT) Received: from ryzen ([2601:644:8000:5b5d:7285:c2ff:fe45:8a32]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-36a3d0d8421sm648868a91.9.2026.05.20.15.00.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2026 15:00:47 -0700 (PDT) From: Rosen Penev To: linux-trace-kernel@vger.kernel.org Cc: Steven Rostedt , Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , linux-kernel@vger.kernel.org (open list:FUNCTION HOOKS (FTRACE)) Subject: [PATCH] ftrace: Use flexible array for hash buckets Date: Wed, 20 May 2026 15:00:30 -0700 Message-ID: <20260520220030.16887-1-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 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" Store ftrace hash buckets in the ftrace_hash allocation instead of allocating the bucket array separately. This keeps the bucket storage tied to the hash lifetime and simplifies the allocation and cleanup paths. Assisted-by: Codex:GPT-5.5 Signed-off-by: Rosen Penev --- kernel/trace/ftrace.c | 17 ++--------------- kernel/trace/trace.h | 2 +- 2 files changed, 3 insertions(+), 16 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b2611de3f594..25a9dca290dd 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1082,10 +1082,7 @@ struct ftrace_func_probe { * it all the time. These are in a read only section such that if * anyone does try to modify it, it will cause an exception. */ -static const struct hlist_head empty_buckets[1]; -static const struct ftrace_hash empty_hash =3D { - .buckets =3D (struct hlist_head *)empty_buckets, -}; +static const struct ftrace_hash empty_hash =3D {}; #define EMPTY_HASH ((struct ftrace_hash *)&empty_hash) =20 struct ftrace_ops global_ops =3D { @@ -1295,7 +1292,6 @@ void free_ftrace_hash(struct ftrace_hash *hash) if (!hash || hash =3D=3D EMPTY_HASH) return; ftrace_hash_clear(hash); - kfree(hash->buckets); kfree(hash); } =20 @@ -1333,20 +1329,11 @@ EXPORT_SYMBOL_GPL(ftrace_free_filter); struct ftrace_hash *alloc_ftrace_hash(int size_bits) { struct ftrace_hash *hash; - int size; =20 - hash =3D kzalloc_obj(*hash); + hash =3D kzalloc_flex(*hash, buckets, BIT(size_bits)); if (!hash) return NULL; =20 - size =3D 1 << size_bits; - hash->buckets =3D kzalloc_objs(*hash->buckets, size); - - if (!hash->buckets) { - kfree(hash); - return NULL; - } - hash->size_bits =3D size_bits; =20 return hash; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 80fe152af1dd..5a3f81f17317 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1000,10 +1000,10 @@ enum { =20 struct ftrace_hash { unsigned long size_bits; - struct hlist_head *buckets; unsigned long count; unsigned long flags; struct rcu_head rcu; + struct hlist_head buckets[]; }; =20 struct ftrace_func_entry * --=20 2.54.0