From nobody Wed Dec 17 10:45:04 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B53D293454 for ; Fri, 9 May 2025 13:13:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746796381; cv=none; b=oF6QY9fDeEHOr3H81HFcu3kl5lsWYOFqR3XD3je4g/ZZFnE22RHM0JeSOY6LFLmdaJcel2k3S0biyUHmbTII/mnqERgrdvEED4Eena5qA4rOUAAjTPdMJGvZaeIDo+Dysjymp34D1P1S4Zwjr005aMS0aAgyqGwaE/DgmtEavow= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746796381; c=relaxed/simple; bh=xwQUJHkXERbxk/si81Gpn8n1YOu4O5M9Z89z+7M7IpQ=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=gWu7pUs9Hxhd0zijDX4dY/korgGxMfAXGq7J+wmGnDwLX7MHkZEOwWdEa8agj6yiM82FE+EbHi5oamaM1WG9eCvjjvNyresW44768iKmgtE6J6o5rijHdzuOxSdvKtcZBBdqyimGQgmde8ymA8Mv1OnJrzgM8Z/alARtvk7B4+M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7D40C4CEEE; Fri, 9 May 2025 13:13:00 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1uDNXQ-00000002bwH-1vyP; Fri, 09 May 2025 09:13:16 -0400 Message-ID: <20250509131316.315091499@goodmis.org> User-Agent: quilt/0.68 Date: Fri, 09 May 2025 09:13:06 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton Subject: [for-next][PATCH 17/31] tracing: Use tracer_tracing_disable() instead of "disabled" field for ftrace_dump_one() References: <20250509131249.340302366@goodmis.org> 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" From: Steven Rostedt The per CPU "disabled" value was the original way to disable tracing when the tracing subsystem was first created. Today, the ring buffer infrastructure has its own way to disable tracing. In fact, things have changed so much since 2008 that many things ignore the disable flag. The ftrace_dump_one() function iterates over all the current tracing CPUs a= nd increments the "disabled" counter before doing the dump, and decrements it afterward. As the disabled flag can be ignored, doing this today is not reliable. Instead use the new tracer_tracing_disable() that calls into the ring buffer code to do the disabling. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://lore.kernel.org/20250505212235.381188238@goodmis.org Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b691af1c1b5a..bb514e988f22 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10484,7 +10484,7 @@ static void ftrace_dump_one(struct trace_array *tr,= enum ftrace_dump_mode dump_m static struct trace_iterator iter; unsigned int old_userobj; unsigned long flags; - int cnt =3D 0, cpu; + int cnt =3D 0; =20 /* * Always turn off tracing when we dump. @@ -10501,9 +10501,8 @@ static void ftrace_dump_one(struct trace_array *tr,= enum ftrace_dump_mode dump_m /* Simulate the iterator */ trace_init_iter(&iter, tr); =20 - for_each_tracing_cpu(cpu) { - atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); - } + /* While dumping, do not allow the buffer to be enable */ + tracer_tracing_disable(tr); =20 old_userobj =3D tr->trace_flags & TRACE_ITER_SYM_USEROBJ; =20 @@ -10562,9 +10561,7 @@ static void ftrace_dump_one(struct trace_array *tr,= enum ftrace_dump_mode dump_m =20 tr->trace_flags |=3D old_userobj; =20 - for_each_tracing_cpu(cpu) { - atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); - } + tracer_tracing_enable(tr); local_irq_restore(flags); } =20 --=20 2.47.2