mbox series

[printk,00/18] preparation for threaded/atomic printing

Message ID 20220924000454.3319186-1-john.ogness@linutronix.de (mailing list archive)
Headers show
Series preparation for threaded/atomic printing | expand

Message

John Ogness Sept. 24, 2022, 12:04 a.m. UTC
Hi,

This series is essentially the first 18 patches of tglx's RFC series
[0] with only minor changes in comments and commit messages. It's
purpose is to lay the groundwork for the upcoming threaded/atomic
console printing posted as the RFC series and demonstrated at
LPC2022 [1].

This series is interesting for mainline because it cleans up various
code and documentation quirks discovered while working on the new
console printing implementation.

Aside from cleanups, the main features introduced here are:

- Converts the console's DIY linked list implementation to hlist.

- Introduces a console list lock (mutex) so that readers (such as
  /proc/consoles) can safely iterate the consoles without blocking
  console printing.

- Adds SRCU support to the console list to prepare for safe console
  list iterating from any context.

- Refactors buffer handling to prepare for per-console, per-cpu,
  per-context atomic printing.

The series has the following parts:

   Patches  1 - 5:   Cleanups

   Patches  6 - 12:  Locking and list conversion

   Patches 13 - 18:  Improved output buffer handling to prepare for
                     code sharing

John Ogness

[0] https://lore.kernel.org/lkml/20220910221947.171557773@linutronix.de
[1] https://lore.kernel.org/lkml/875yheqh6v.fsf@jogness.linutronix.de

Thomas Gleixner (18):
  printk: Make pr_flush() static
  printk: Declare log_wait properly
  printk: Remove write only variable nr_ext_console_drivers
  printk: Remove bogus comment vs. boot consoles
  printk: Mark __printk percpu data ready __ro_after_init
  printk: Protect [un]register_console() with a mutex
  printk: Convert console list walks for readers to list lock
  parisc: Put console abuse into one place
  serial: kgdboc: Lock console list in probe function
  kgbd: Pretend that console list walk is safe
  printk: Convert console_drivers list to hlist
  printk: Prepare for SCRU console list protection
  printk: Move buffer size defines
  printk: Document struct console
  printk: Add struct cons_text_buf
  printk: Use struct cons_text_buf
  printk: Use an output descriptor struct for emit
  printk: Handle dropped message smarter

 arch/parisc/include/asm/pdc.h |   2 +-
 arch/parisc/kernel/pdc_cons.c |  55 +++--
 arch/parisc/kernel/traps.c    |  17 +-
 drivers/tty/serial/kgdboc.c   |   9 +-
 drivers/tty/tty_io.c          |   6 +-
 fs/proc/consoles.c            |  11 +-
 fs/proc/kmsg.c                |   2 -
 include/linux/console.h       | 197 +++++++++++++---
 include/linux/printk.h        |   9 -
 include/linux/syslog.h        |   3 +
 kernel/debug/kdb/kdb_io.c     |   7 +-
 kernel/printk/printk.c        | 414 ++++++++++++++++++++++------------
 12 files changed, 499 insertions(+), 233 deletions(-)


base-commit: dc453dd89daacdc0da6d66234aa27e417df7edcd

Comments

Greg KH Sept. 24, 2022, 6:44 a.m. UTC | #1
On Sat, Sep 24, 2022 at 02:10:36AM +0206, John Ogness wrote:
> Hi,
> 
> This series is essentially the first 18 patches of tglx's RFC series
> [0] with only minor changes in comments and commit messages. It's
> purpose is to lay the groundwork for the upcoming threaded/atomic
> console printing posted as the RFC series and demonstrated at
> LPC2022 [1].
> 
> This series is interesting for mainline because it cleans up various
> code and documentation quirks discovered while working on the new
> console printing implementation.
> 
> Aside from cleanups, the main features introduced here are:
> 
> - Converts the console's DIY linked list implementation to hlist.
> 
> - Introduces a console list lock (mutex) so that readers (such as
>   /proc/consoles) can safely iterate the consoles without blocking
>   console printing.
> 
> - Adds SRCU support to the console list to prepare for safe console
>   list iterating from any context.
> 
> - Refactors buffer handling to prepare for per-console, per-cpu,
>   per-context atomic printing.
> 
> The series has the following parts:
> 
>    Patches  1 - 5:   Cleanups
> 
>    Patches  6 - 12:  Locking and list conversion
> 
>    Patches 13 - 18:  Improved output buffer handling to prepare for
>                      code sharing
> 

These all look great to me, thanks for resending them.

Do you want them to go through my serial/tty tree, or is there some
other tree to take them through (printk?)

If they are to go through someone else's tree, feel free to add:

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sergey Senozhatsky Sept. 24, 2022, 9:47 a.m. UTC | #2
On (22/09/24 02:10), John Ogness wrote:
> 
>    Patches  6 - 12:  Locking and list conversion
> 

A quick question: I wonder why xenfb_make_preferred_console() isn't
converted to list lock and for_each_registered_console()?
John Ogness Sept. 25, 2022, 3:23 p.m. UTC | #3
On 2022-09-24, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> These all look great to me, thanks for resending them.
>
> Do you want them to go through my serial/tty tree, or is there some
> other tree to take them through (printk?)

Thanks Greg. but I would prefer they go through the printk tree. In
particular, I want Petr to have the chance to review patches 15-18.

> If they are to go through someone else's tree, feel free to add:
>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Thanks!

John
Petr Mladek Sept. 29, 2022, 4:33 p.m. UTC | #4
On Sat 2022-09-24 02:10:36, John Ogness wrote:
> Hi,
> 
> This series is essentially the first 18 patches of tglx's RFC series
> [0] with only minor changes in comments and commit messages. It's
> purpose is to lay the groundwork for the upcoming threaded/atomic
> console printing posted as the RFC series and demonstrated at
> LPC2022 [1].
> 
> This series is interesting for mainline because it cleans up various
> code and documentation quirks discovered while working on the new
> console printing implementation.
> 
> Aside from cleanups, the main features introduced here are:
> 
> - Converts the console's DIY linked list implementation to hlist.
> 
> - Introduces a console list lock (mutex) so that readers (such as
>   /proc/consoles) can safely iterate the consoles without blocking
>   console printing.
> 
> - Adds SRCU support to the console list to prepare for safe console
>   list iterating from any context.
> 
> - Refactors buffer handling to prepare for per-console, per-cpu,
>   per-context atomic printing.
> 
> The series has the following parts:
> 
>    Patches  1 - 5:   Cleanups
> 
>    Patches  6 - 12:  Locking and list conversion
> 
>    Patches 13 - 18:  Improved output buffer handling to prepare for
>                      code sharing
> 
> Thomas Gleixner (18):
>   printk: Make pr_flush() static
>   printk: Declare log_wait properly
>   printk: Remove write only variable nr_ext_console_drivers
>   printk: Remove bogus comment vs. boot consoles
>   printk: Mark __printk percpu data ready __ro_after_init

JFYI, I have pushed the first 5 cleanup patches into printk/linux.git,
branch rework/kthreads. The aim is to get them into 6.1.

The rest of the patchset is still being discussed.

Best Regards,
Petr