linux-kernel - Re: [PATCH -next] ftrace: Fix potential warning in trace_printk_seq during ftrace

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Message-ID: <edc9900c-b2d9-49f9-bd12-cd44f11b89a1@huaweicloud.com>
Date: Fri, 22 Aug 2025 09:35:43 +0800
From: Tengda Wu <wutengda@...weicloud.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Ingo Molnar <mingo@...e.hu>, linux-trace-kernel@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] ftrace: Fix potential warning in trace_printk_seq
 during ftrace_dump



On 2025/8/21 22:51, Steven Rostedt wrote:
> On Thu, 21 Aug 2025 09:53:53 +0800
> Tengda Wu <wutengda@...weicloud.com> wrote:
> 
>> There remains an edge case that concerns me: if size is 0, setting len to
>> size - 1 would cause an underflow. Should we handle this edge case?
> 
> When the trace_seq is allocated, the size is set to 8K. If size is ever
> zero, then there would be no buffer. So no, we should not worry about that
> edge case because if it happened then we have a lot of other things to
> worry about.
> 
> -- Steve

Got it, thanks for the clarification.

-- Tengda