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From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: John Ogness <john.ogness@linutronix.de>
Cc: linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrea Parri <andrea.parri@amarulasolutions.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Brendan Higgins <brendanhiggins@google.com>,
	kexec@lists.infradead.org
Subject: Re: [RFC PATCH v5 1/3] printk-rb: new printk ringbuffer implementation (writer)
Date: Mon, 9 Dec 2019 18:27:56 +0900
Message-ID: <20191209092756.GH88619@google.com> (raw)
In-Reply-To: <20191128015235.12940-2-john.ogness@linutronix.de>

On (19/11/28 02:58), John Ogness wrote:
> + * Sample reader code::
> + *
> + *	struct printk_info info;
> + *	char text_buf[32];
> + *	char dict_buf[32];
> + *	u64 next_seq = 0;
> + *	struct printk_record r = {
> + *		.info		= &info,
> + *		.text_buf	= &text_buf[0],
> + *		.dict_buf	= &dict_buf[0],
> + *		.text_buf_size	= sizeof(text_buf),
> + *		.dict_buf_size	= sizeof(dict_buf),
> + *	};
> + *
> + *	while (prb_read_valid(&rb, next_seq, &r)) {
> + *		if (info.seq != next_seq)
> + *			pr_warn("lost %llu records\n", info.seq - next_seq);
> + *
> + *		if (info.text_len > r.text_buf_size) {
> + *			pr_warn("record %llu text truncated\n", info.seq);
> + *			text_buf[sizeof(text_buf) - 1] = 0;
> + *		}
> + *
> + *		if (info.dict_len > r.dict_buf_size) {
> + *			pr_warn("record %llu dict truncated\n", info.seq);
> + *			dict_buf[sizeof(dict_buf) - 1] = 0;
> + *		}
> + *
> + *		pr_info("%llu: %llu: %s;%s\n", info.seq, info.ts_nsec,
> + *			&text_buf[0], info.dict_len ? &dict_buf[0] : "");
> + *
> + *		next_seq = info.seq + 1;
> + *	}
> + */

Will this loop ever end? :)

pr_info() adds data to ringbuffer, which prb_read_valid() reads, so pr_info()
can add more data, which prb_read_valid() will read, so pr_info()...

	-ss

  parent reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-28  1:52 [RFC PATCH v5 0/3] printk: new ringbuffer implementation John Ogness
2019-11-28  1:52 ` [RFC PATCH v5 1/3] printk-rb: new printk ringbuffer implementation (writer) John Ogness
2019-12-02 15:48   ` Petr Mladek
2019-12-02 15:59     ` Petr Mladek
2019-12-02 16:37       ` John Ogness
2019-12-03  1:17         ` Sergey Senozhatsky
2019-12-03 14:18           ` Steven Rostedt
2019-12-05 12:01             ` John Ogness
2019-12-03  8:54         ` Petr Mladek
2019-12-03 14:13     ` John Ogness
2019-12-03 14:36       ` Petr Mladek
2019-12-09  9:19     ` Sergey Senozhatsky
2019-12-09  7:42   ` Sergey Senozhatsky
2019-12-09  9:00     ` John Ogness
2019-12-09  9:27   ` Sergey Senozhatsky [this message]
2019-12-09  9:34     ` John Ogness
2019-12-21 14:22   ` Andrea Parri
2019-12-23 16:01     ` John Ogness
2020-01-03 10:24       ` Petr Mladek
2020-01-04 14:33         ` Andrea Parri
2019-11-28  1:52 ` [RFC PATCH v5 2/3] printk-rb: new printk ringbuffer implementation (reader) John Ogness
2019-12-03 12:06   ` Petr Mladek
2019-12-03 13:46     ` John Ogness
2019-12-04 12:54       ` Petr Mladek
2019-12-04 13:28         ` John Ogness
2019-12-09  8:43   ` Sergey Senozhatsky
2019-12-09  9:03     ` Sergey Senozhatsky
2019-12-09  9:09     ` John Ogness
2019-11-28  1:52 ` [RFC PATCH v5 3/3] printk-rb: add test module John Ogness
2019-12-09  8:44   ` Sergey Senozhatsky
2019-12-05 13:46 ` [RFC PATCH v5 0/3] printk: new ringbuffer implementation Prarit Bhargava
2019-12-05 14:05   ` John Ogness
2019-12-06 14:16     ` Prarit Bhargava
2020-01-27 12:20 ` Eugeniu Rosca

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