From mboxrd@z Thu Jan 1 00:00:00 1970 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 7927651C37; Mon, 11 Dec 2023 18:52:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EX+t3fOQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F295CC433C8; Mon, 11 Dec 2023 18:52:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1702320741; bh=bWX/HUoxtTJ4ANCku19NTNJ+4sX86vOZkTxH+ZaMekw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EX+t3fOQlg0OtJczAzKqHRe+A9dnlxEyYeAJv64OXNMs6c856D0bB5ufXsZo2WOrh 7ZkqyyD4LkhxJQAudhFpTky9JdRl1AfdjEo8x4reb6tuxYJFHeraWYTn9nrN15j7HD 7iVLR5iMHWCKG/ql5G8zTquK3hyPAvM0HKUkVykM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.1 145/194] tracing: Stop current tracer when resizing buffer Date: Mon, 11 Dec 2023 19:22:15 +0100 Message-ID: <20231211182043.089150597@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231211182036.606660304@linuxfoundation.org> References: <20231211182036.606660304@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt (Google) [ Upstream commit d78ab792705c7be1b91243b2544d1a79406a2ad7 ] When the ring buffer is being resized, it can cause side effects to the running tracer. For instance, there's a race with irqsoff tracer that swaps individual per cpu buffers between the main buffer and the snapshot buffer. The resize operation modifies the main buffer and then the snapshot buffer. If a swap happens in between those two operations it will break the tracer. Simply stop the running tracer before resizing the buffers and enable it again when finished. Link: https://lkml.kernel.org/r/20231205220010.748996423@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Fixes: 3928a8a2d9808 ("ftrace: make work with new ring buffer") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 048728807f265..d2db4d6f0f2fd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6268,9 +6268,12 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, if (!tr->array_buffer.buffer) return 0; + /* Do not allow tracing while resizng ring buffer */ + tracing_stop_tr(tr); + ret = ring_buffer_resize(tr->array_buffer.buffer, size, cpu); if (ret < 0) - return ret; + goto out_start; #ifdef CONFIG_TRACER_MAX_TRACE if (!tr->current_trace->use_max_tr) @@ -6298,7 +6301,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, WARN_ON(1); tracing_disabled = 1; } - return ret; + goto out_start; } update_buffer_entries(&tr->max_buffer, cpu); @@ -6307,7 +6310,8 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, #endif /* CONFIG_TRACER_MAX_TRACE */ update_buffer_entries(&tr->array_buffer, cpu); - + out_start: + tracing_start_tr(tr); return ret; } -- 2.42.0