linux-kernel - [PATCH printk v5 0/8] provide nbcon base

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Date:   Sat, 16 Sep 2023 21:25:59 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH printk v5 0/8] provide nbcon base

Hi,

This is v5 of a series to introduce the new non-BKL (nbcon)
consoles. v4 is here [0]. For information about the motivation
of the atomic consoles, please read the cover letter of v1 [1].

This series focuses on providing the base functionality of the
nbcon consoles. In particular, it implements the ownership and
priority semantics for nbcon consoles. This series does _not_
include threaded printing, atomic printing regions, or nbcon
drivers. Those features will be added in separate follow-up
series.

The changes since v4:

- Remove nbcon_seq_init() and use nbcon_seq_force() instead.

- For nbcon_seq_force(), use the oldest record if the specified
  record no longer exists.

- For all try_acquire_*() variants, do not update the nbcon
  state on success since it was not used.

- For nbcon_context_try_acquire_requested(), replace the cmpxhg
  loop with a single cmpxchg.

- For nbcon_context_try_acquire_requested(), remove an explicit
  check for @unsafe_takeover. The nbcon_waiter_matches() check
  is enough to detect unsafe hostile takeovers.

- Rename nbcon_context_acquire_hostile() back to
  nbcon_context_try_acquire_hostile().

- Decide in nbcon_context_try_acquire_hostile() if an unsafe
  hostile acquire is allowed rather than at the end of and
  after nbcon_context_try_acquire_handover().

- For register_console(), call nbcon_free() if it is a braille
  console.

- Change many comments as suggested by pmladek. In the feedback
  thread I mentioned some other comment changes that I made.

- Added various WARN_ON_ONCE() checks as suggested by pmladek.

John Ogness

[0] https://lore.kernel.org/lkml/20230908185008.468566-1-john.ogness@linutronix.de

[1] https://lore.kernel.org/lkml/20230302195618.156940-1-john.ogness@linutronix.de

John Ogness (1):
  printk: Make static printk buffers available to nbcon

Thomas Gleixner (7):
  printk: Add non-BKL (nbcon) console basic infrastructure
  printk: nbcon: Add acquire/release logic
  printk: nbcon: Add buffer management
  printk: nbcon: Add ownership state functions
  printk: nbcon: Add sequence handling
  printk: nbcon: Add emit function and callback function for atomic
    printing
  printk: nbcon: Allow drivers to mark unsafe regions and check state

 include/linux/console.h  |  129 +++++
 kernel/printk/Makefile   |    2 +-
 kernel/printk/internal.h |   31 ++
 kernel/printk/nbcon.c    | 1029 ++++++++++++++++++++++++++++++++++++++
 kernel/printk/printk.c   |   78 ++-
 5 files changed, 1245 insertions(+), 24 deletions(-)
 create mode 100644 kernel/printk/nbcon.c


base-commit: 189f53ec666838729ab29a220ca4c1e1f1359f95
-- 
2.39.2