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Date: Fri, 27 Oct 2023 06:54:51 +0200
From: Christoph Hellwig <hch@lst.de>
To: Kees Cook <keescook@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
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	linux-trace-kernel@vger.kernel.org,
	Yosry Ahmed <yosryahmed@google.com>, linux-kernel@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2] seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()
Message-ID: <20231027045451.GA7838@lst.de>
References: <20231026194033.it.702-kees@kernel.org>
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In-Reply-To: <20231026194033.it.702-kees@kernel.org>
User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, Oct 26, 2023 at 12:40:37PM -0700, Kees Cook wrote:
> Solve two ergonomic issues with struct seq_buf;
> 
> 1) Too much boilerplate is required to initialize:
> 
> 	struct seq_buf s;
> 	char buf[32];
> 
> 	seq_buf_init(s, buf, sizeof(buf));
> 
> Instead, we can build this directly on the stack. Provide
> DECLARE_SEQ_BUF() macro to do this:
> 
> 	DECLARE_SEQ_BUF(s, 32);

DECLARE_SEQ_BUF_ONSTACK maybe?  But otherwise this looks like a good
concept.

> Instead, we can just return s->buffer direction after terminating it
> in refactored seq_buf_terminate(), now known as seq_buf_str():
> 
> 	do_soemthing(seq_buf_str(s));

Looks good.  Btw, one typical do_something would be printing it,
so adding a format specifier that's using this helper would also
probably be very useful.