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From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrea Parri <parri.andrea@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Paul McKenney <paulmck@kernel.org>,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 0/4] printk: replace ringbuffer
Date: Thu, 09 Jul 2020 09:09:31 +0206	[thread overview]
Message-ID: <87wo3d9nlo.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <20200708152005.GF4751@alley>

On 2020-07-08, Petr Mladek <pmladek@suse.com> wrote:
> OK, I think that we are ready to try this in linux-next.
> I am going to push it there via printk/linux.git.
>
> [...]
> 
> Of course, there are still many potential problems. The following comes
> to my mind:
>
> [...]
>
>    + Debugging tools accessing the buffer directly would need to
>      understand the new structure. Fortunately John provided
>      patches for the most prominent ones.

The next series in the printk-rework (move LOG_CONT handling from
writers to readers) makes some further changes that, while not
incompatible, could affect the output of existing tools. It may be a
good idea to let the new ringbuffer sit in linux-next until the next
series has been discussed/reviewed/merged. After the next series,
everything will be in place (with regard to userspace tools) to finish
the rework.

As reminder, here are all the steps planned for the full rework:

1. replace ringbuffer
2. implement NMI-safe LOG_CONT (i.e. move handling to readers)
3. remove logbuf_lock
4. remove safe buffers
5. implement per-console printing kthreads
6. implement emergency mode and write_atomic() support
7. implement write_atomic() for 8250 UART

Some of the steps may be combined into a single series if the changes
are not too dramatic.

John Ogness

  reply	other threads:[~2020-07-09  7:03 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-07 14:59 [PATCH v4 0/4] printk: replace ringbuffer John Ogness
2020-07-07 14:59 ` [PATCH v4 1/4] crash: add VMCOREINFO macro to define offset in a struct declared by typedef John Ogness
2020-07-07 14:59 ` [PATCH v4 2/4] printk: add lockless ringbuffer John Ogness
2020-07-07 14:59 ` [PATCH v4 3/4] Revert "printk: lock/unlock console only for new logbuf entries" John Ogness
2020-07-08 14:34   ` Petr Mladek
2020-07-09  1:20   ` Sergey Senozhatsky
2020-07-07 14:59 ` [PATCH v4 4/4] printk: use the lockless ringbuffer John Ogness
2020-07-07 19:25   ` kernel test robot
2020-07-08 13:18     ` John Ogness
2020-07-08 14:35   ` Petr Mladek
2020-07-08 19:24   ` kernel test robot
2020-07-09  7:14   ` [printk] 18a2dc6982: ltp.kmsg01.fail kernel test robot
2020-07-09  8:33     ` Sergey Senozhatsky
2020-07-09 10:14       ` John Ogness
2020-07-09 10:59         ` Petr Mladek
2020-07-09 11:13           ` Petr Mladek
2020-07-09 11:17             ` John Ogness
2020-07-09 12:25               ` Petr Mladek
2020-07-09 13:07                 ` Sergey Senozhatsky
2020-07-09 14:41                   ` Petr Mladek
2020-07-08 15:20 ` [PATCH v4 0/4] printk: replace ringbuffer Petr Mladek
2020-07-09  7:03   ` John Ogness [this message]
2020-07-10  9:11     ` Petr Mladek
2020-07-10  9:52       ` John Ogness
2020-07-10 14:15         ` Petr Mladek
2020-07-14  2:56         ` Sergey Senozhatsky

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