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Message-Id: <20240804005138.3722656-1-john.ogness@linutronix.de>
Date: Sun, 4 Aug 2024 02:57:03 +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,
Miguel Ojeda <ojeda@...nel.org>,
"Paul E. McKenney" <paulmck@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>,
linux-serial@...r.kernel.org,
Russell King <linux@...linux.org.uk>,
Tony Lindgren <tony@...mide.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Arnd Bergmann <arnd@...db.de>,
Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
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Lino Sanfilippo <l.sanfilippo@...bus.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>,
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Ingo Molnar <mingo@...hat.com>,
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Waiman Long <longman@...hat.com>
Subject: [PATCH printk v7 00/35] wire up write_atomic() printing
Hi,
This is v7 of a series to wire up the nbcon consoles so that
they actually perform printing using their write_atomic()
callback. v6 is here [0]. For information about the motivation
of the atomic consoles, please read the cover letter of v1 [1].
The main focus of this series:
- For nbcon consoles, always call write_atomic() directly from
printk() caller context for the panic CPU.
- For nbcon consoles, call write_atomic() when unlocking the
console lock.
- Only perform the console lock/unlock dance if legacy or boot
consoles are registered.
- For legacy consoles, if nbcon consoles are registered, do not
attempt to print from printk() caller context for the panic
CPU until nbcon consoles have had a chance to print the most
significant messages.
- Mark emergency sections. In these sections, every printk()
call will attempt to directly flush to the consoles using the
EMERGENCY priority.
This series does _not_ include threaded printing or nbcon
drivers. Those features will be added in separate follow-up
series.
The changes since v6:
- When a CPU is in an emergency state, printk() calls will now
flush directly to all consoles using the EMERGENCY priority.
- Remove usage and implementation of
nbcon_cpu_emergency_flush().
- Add printk_get_console_flush_type() to query available flush
types and use it at all flushing call sites.
- In vprintk_emit(), always use nbcon_atomic flushing if it is
available.
- When exiting nbcon_device_release(), flush using the legacy
loop if nbcon_atomic flushing is not available.
- In console_flush_on_panic(), make sure nbcon_atomic flushing
is allowed before flushing.
- In pr_flush(), always take the console_lock because there is
no synchronization against register_console() and legacy
consoles could register while waiting.
- In __wake_up_klogd(), remove check if PENDING_OUTPUT is
needed. If PENDING_OUTPUT is set, it is needed.
- Rename is_printk_deferred() to is_printk_legacy_deferred().
- Remove nbcon_init(), consolidate it into nbcon_alloc().
- Improve documentation about nbcon owner/waiter matching
rules.
- Allow nbcon_get_cpu_emergency_nesting() to run without
migration disabled.
- Clarify that nbcon_get_default_prio() can run without
migration disabled.
John Ogness
[0] https://lore.kernel.org/lkml/20240527063749.391035-1-john.ogness@linutronix.de
[1] https://lore.kernel.org/lkml/20230302195618.156940-1-john.ogness@linutronix.de
John Ogness (30):
printk: Add notation to console_srcu locking
printk: nbcon: Consolidate alloc() and init()
printk: nbcon: Clarify rules of the owner/waiter matching
printk: nbcon: Remove return value for write_atomic()
printk: nbcon: Add detailed doc for write_atomic()
printk: nbcon: Add callbacks to synchronize with driver
printk: nbcon: Use driver synchronization while (un)registering
serial: core: Provide low-level functions to lock port
serial: core: Introduce wrapper to set @uart_port->cons
console: Improve console_srcu_read_flags() comments
nbcon: Add API to acquire context for non-printing operations
serial: core: Acquire nbcon context in port->lock wrapper
printk: nbcon: Do not rely on proxy headers
printk: Make console_is_usable() available to nbcon.c
printk: Let console_is_usable() handle nbcon
printk: Add @flags argument for console_is_usable()
printk: nbcon: Add helper to assign priority based on CPU state
printk: Track registered boot consoles
printk: nbcon: Use nbcon consoles in console_flush_all()
printk: Add is_printk_legacy_deferred()
printk: nbcon: Flush new records on device_release()
printk: Flush nbcon consoles first on panic
printk: nbcon: Add unsafe flushing on panic
printk: Avoid console_lock dance if no legacy or boot consoles
printk: Track nbcon consoles
printk: Coordinate direct printing in panic
printk: Add helper for flush type logic
panic: Mark emergency section in oops
rcu: Mark emergency sections in rcu stalls
lockdep: Mark emergency sections in lockdep splats
Petr Mladek (1):
printk: Properly deal with nbcon consoles on seq init
Sebastian Andrzej Siewior (1):
printk: Check printk_deferred_enter()/_exit() usage
Thomas Gleixner (3):
printk: nbcon: Provide function to flush using write_atomic()
printk: nbcon: Implement emergency sections
panic: Mark emergency section in warn
drivers/tty/serial/8250/8250_core.c | 6 +-
drivers/tty/serial/amba-pl011.c | 2 +-
drivers/tty/serial/serial_core.c | 16 +-
include/linux/console.h | 110 +++++-
include/linux/printk.h | 33 +-
include/linux/serial_core.h | 117 +++++-
kernel/locking/lockdep.c | 83 +++-
kernel/panic.c | 9 +
kernel/printk/internal.h | 130 ++++++-
kernel/printk/nbcon.c | 565 +++++++++++++++++++++++++---
kernel/printk/printk.c | 250 +++++++++---
kernel/printk/printk_ringbuffer.h | 2 +
kernel/printk/printk_safe.c | 23 +-
kernel/rcu/tree_exp.h | 7 +
kernel/rcu/tree_stall.h | 9 +
15 files changed, 1211 insertions(+), 151 deletions(-)
base-commit: 8bf100092d60bf586bbc1a3a2cd833bb212d9d53
--
2.39.2
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