linux-kernel - Re: [PATCH] tracing: move buffer in trace

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Message-ID: <20250902160020.5cd24fce@batman.local.home>
Date: Tue, 2 Sep 2025 16:00:20 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Elijah <me@...jahs.space>
Cc: Elijah Wright <git@...jahs.space>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: move buffer in trace_seq to end of struct

On Thu, 21 Aug 2025 11:32:17 -0700
Elijah <me@...jahs.space> wrote:

> can we maybe encode the overflow state in seq_buf? check if 
> seq_buf_has_overflowed and clamp len back to the used size 
> (seq_buf_used) in a helper?

I could add a bit to the size?

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 52791e070506..ea4996851901 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -20,8 +20,9 @@
  */
 struct seq_buf {
 	char			*buffer;
-	size_t			size;
-	size_t			len;
+	unsigned int		size;
+	unsigned int		len:31;
+	unsigned int		full:1;
 };
 
 #define DECLARE_SEQ_BUF(NAME, SIZE)			\


-- Steve