From nobody Mon Feb 9 00:25:49 2026 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 7AA482C9E; Fri, 23 Feb 2024 01:31:53 +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=1708651913; cv=none; b=NVWNr7TBS7cuB1UlCsMQlKomQd+6B7uRMXdXELEmQGoLPNXHtm7p5ZbV6fQrUnVzwZ2gExHoTvr5vroW5SHuW1lOKjsm4HbN+ADiepkPZGOvNOJd2yynZzhR21OIIUzx2JdIAyJDislNxzMZIODo6r9YUBSM5g0OQ7+Ov2+rZM8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708651913; c=relaxed/simple; bh=4NKBpeaolII1sBupq/IxTuoIHTKsguTYUdtlaE5KXXQ=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=WHPhmHMCVUaFXBdBSoW9KAK31QxLqpAQrqw1tX4C4Am8PqDxEwCEQihhBhbnS+AcPS0LBvRXtCkG//weOW7/zNEut5UDscK7K8noIptkO3mMKn0uHDoTi396D2hoStWL8qXQu+ri6rb2giGji2+fUYi6mNed/YCGK9MqG2kWvKs= 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 24CF8C43390; Fri, 23 Feb 2024 01:31:53 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rdKRc-00000006ogb-3daK; Thu, 22 Feb 2024 20:33:44 -0500 Message-ID: <20240223013344.729055907@goodmis.org> User-Agent: quilt/0.67 Date: Thu, 22 Feb 2024 20:33:25 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Vincent Donnefort Subject: [PATCH 2/2] tracing: Decrement the snapshot if the snapshot trigger fails to register References: <20240223013323.798805901@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 (Google)" Running the ftrace selftests caused the ring buffer mapping test to fail. Investigating, I found that the snapshot counter would be incremented every time a snapshot trigger was added, even if that snapshot trigger failed. # cd /sys/kernel/tracing # echo "snapshot" > events/sched/sched_process_fork/trigger # echo "snapshot" > events/sched/sched_process_fork/trigger -bash: echo: write error: File exists That second one that fails increments the snapshot counter but doesn't decrement it. It needs to be decremented when the snapshot fails. Fixes: 16f7e48ffc53a ("tracing: Add snapshot refcount") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_trigger.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_event= s_trigger.c index 62e4f58b8671..4bec043c8690 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -1491,7 +1491,10 @@ register_snapshot_trigger(char *glob, if (ret < 0) return ret; =20 - return register_trigger(glob, data, file); + ret =3D register_trigger(glob, data, file); + if (ret < 0) + tracing_disarm_snapshot(file->tr); + return ret; } =20 static void unregister_snapshot_trigger(char *glob, --=20 2.43.0