From: Petr Mladek <pmladek@suse.com>
To: John Ogness <john.ogness@linutronix.de>
Cc: Andrea Parri <parri.andrea@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Paul McKenney <paulmck@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: syslog size unread: was: [PATCH v3 3/3] printk: use the lockless ringbuffer
Date: Thu, 25 Jun 2020 17:20:42 +0200 [thread overview]
Message-ID: <20200625152042.GI8444@alley> (raw)
In-Reply-To: <20200618144919.9806-4-john.ogness@linutronix.de>
On Thu 2020-06-18 16:55:19, John Ogness wrote:
> Replace the existing ringbuffer usage and implementation with
> lockless ringbuffer usage. Even though the new ringbuffer does not
> require locking, all existing locking is left in place. Therefore,
> this change is purely replacing the underlining ringbuffer.
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1609,11 +1633,15 @@ int do_syslog(int type, char __user *buf, int len, int source)
> break;
> /* Number of chars in the log buffer */
> case SYSLOG_ACTION_SIZE_UNREAD:
> + if (source != SYSLOG_FROM_PROC) {
> + text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
> + if (!text)
> + return -ENOMEM;
The buffer is needed only to count lines to count the size of
added prefixes. Could we use the new prb_read_valid_info() that
allows to get the number of lines without actually reading the buffer?
> +
> + }
> logbuf_lock_irq();
> - if (syslog_seq < log_first_seq) {
> + if (syslog_seq < prb_first_seq(prb)) {
> /* messages are gone, move to first one */
> - syslog_seq = log_first_seq;
> - syslog_idx = log_first_idx;
> + syslog_seq = prb_first_seq(prb);
> syslog_partial = 0;
> }
> if (source == SYSLOG_FROM_PROC) {
Best Regards,
Petr
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next prev parent reply other threads:[~2020-06-25 15:20 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-18 14:49 [PATCH v3 0/3] printk: replace ringbuffer John Ogness
2020-06-18 14:49 ` [PATCH v3 1/3] crash: add VMCOREINFO macro to define offset in a struct declared by typedef John Ogness
2020-06-24 8:49 ` Petr Mladek
2020-07-04 9:30 ` Baoquan He
2020-06-18 14:49 ` [PATCH v3 2/3] printk: add lockless ringbuffer John Ogness
2020-06-29 15:32 ` Paul E. McKenney
2020-07-02 8:35 ` Petr Mladek
2020-06-18 14:49 ` [PATCH v3 3/3] printk: use the " John Ogness
2020-06-18 18:23 ` kernel test robot
2020-06-18 18:23 ` [RFC PATCH] printk: _printk_rb_static_dict can be static kernel test robot
2020-06-19 6:49 ` John Ogness
2020-06-19 12:29 ` Steven Rostedt
2020-06-25 8:16 ` truncate dict: was: Re: [PATCH v3 3/3] printk: use the lockless ringbuffer Petr Mladek
2020-06-26 13:48 ` John Ogness
2020-06-25 8:28 ` buffer allocation: was: " Petr Mladek
2020-06-26 15:02 ` John Ogness
2020-06-29 14:04 ` Petr Mladek
2020-06-29 21:57 ` John Ogness
2020-07-02 13:27 ` Petr Mladek
2020-06-25 12:09 ` record_printk_text tricks: " Petr Mladek
2020-06-25 15:25 ` Petr Mladek
2020-06-26 23:25 ` John Ogness
2020-06-25 15:17 ` pending output optimization: " Petr Mladek
2020-07-01 19:58 ` John Ogness
2020-06-25 15:20 ` Petr Mladek [this message]
2020-06-29 21:51 ` syslog size unread: " John Ogness
2020-07-02 8:25 ` lijiang
2020-07-02 9:02 ` John Ogness
2020-07-02 9:43 ` lijiang
2020-07-02 13:31 ` Petr Mladek
2020-07-04 1:12 ` lijiang
2020-07-03 11:54 ` John Ogness
2020-07-08 5:50 ` lijiang
2020-06-25 7:19 ` [PATCH v3 0/3] printk: replace ringbuffer Dave Young
2020-06-25 14:13 ` John Ogness
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