2005-04-16 15:20:36 -07:00
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2018-07-31 13:06:57 +02:00
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2023-01-09 11:13:54 +01:06
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printk: nbcon: Introduce printer kthreads
Provide the main implementation for running a printer kthread
per nbcon console that is takeover/handover aware. This
includes:
- new mandatory write_thread() callback
- kthread creation
- kthread main printing loop
- kthread wakeup mechanism
- kthread shutdown
kthread creation is a bit tricky because consoles may register
before kthreads can be created. In such cases, registration
will succeed, even though no kthread exists. Once kthreads can
be created, an early_initcall will set @printk_kthreads_ready.
If there are no registered boot consoles, the early_initcall
creates the kthreads for all registered nbcon consoles. If
kthread creation fails, the related console is unregistered.
If there are registered boot consoles when
@printk_kthreads_ready is set, no kthreads are created until
the final boot console unregisters.
Once kthread creation finally occurs, @printk_kthreads_running
is set so that the system knows kthreads are available for all
registered nbcon consoles.
If @printk_kthreads_running is already set when the console
is registering, the kthread is created during registration. If
kthread creation fails, the registration will fail.
Until @printk_kthreads_running is set, console printing occurs
directly via the console_lock.
kthread shutdown on system shutdown/reboot is necessary to
ensure the printer kthreads finish their printing so that the
system can cleanly transition back to direct printing via the
console_lock in order to reliably push out the final
shutdown/reboot messages. @printk_kthreads_running is cleared
before shutting down the individual kthreads.
The kthread uses a new mandatory write_thread() callback that
is called with both device_lock() and the console context
acquired.
The console ownership handling is necessary for synchronization
against write_atomic() which is synchronized only via the
console context ownership.
The device_lock() serializes acquiring the console context with
NBCON_PRIO_NORMAL. It is needed in case the device_lock() does
not disable preemption. It prevents the following race:
CPU0 CPU1
[ task A ]
nbcon_context_try_acquire()
# success with NORMAL prio
# .unsafe == false; // safe for takeover
[ schedule: task A -> B ]
WARN_ON()
nbcon_atomic_flush_pending()
nbcon_context_try_acquire()
# success with EMERGENCY prio
# flushing
nbcon_context_release()
# HERE: con->nbcon_state is free
# to take by anyone !!!
nbcon_context_try_acquire()
# success with NORMAL prio [ task B ]
[ schedule: task B -> A ]
nbcon_enter_unsafe()
nbcon_context_can_proceed()
BUG: nbcon_context_can_proceed() returns "true" because
the console is owned by a context on CPU0 with
NBCON_PRIO_NORMAL.
But it should return "false". The console is owned
by a context from task B and we do the check
in a context from task A.
Note that with these changes, the printer kthreads do not yet
take over full responsibility for nbcon printing during normal
operation. These changes only focus on the lifecycle of the
kthreads.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-7-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-04 14:11:25 +02:06
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|
2022-11-16 17:27:15 +01:06
|
|
|
|
printk: nbcon: Introduce printer kthreads
Provide the main implementation for running a printer kthread
per nbcon console that is takeover/handover aware. This
includes:
- new mandatory write_thread() callback
- kthread creation
- kthread main printing loop
- kthread wakeup mechanism
- kthread shutdown
kthread creation is a bit tricky because consoles may register
before kthreads can be created. In such cases, registration
will succeed, even though no kthread exists. Once kthreads can
be created, an early_initcall will set @printk_kthreads_ready.
If there are no registered boot consoles, the early_initcall
creates the kthreads for all registered nbcon consoles. If
kthread creation fails, the related console is unregistered.
If there are registered boot consoles when
@printk_kthreads_ready is set, no kthreads are created until
the final boot console unregisters.
Once kthread creation finally occurs, @printk_kthreads_running
is set so that the system knows kthreads are available for all
registered nbcon consoles.
If @printk_kthreads_running is already set when the console
is registering, the kthread is created during registration. If
kthread creation fails, the registration will fail.
Until @printk_kthreads_running is set, console printing occurs
directly via the console_lock.
kthread shutdown on system shutdown/reboot is necessary to
ensure the printer kthreads finish their printing so that the
system can cleanly transition back to direct printing via the
console_lock in order to reliably push out the final
shutdown/reboot messages. @printk_kthreads_running is cleared
before shutting down the individual kthreads.
The kthread uses a new mandatory write_thread() callback that
is called with both device_lock() and the console context
acquired.
The console ownership handling is necessary for synchronization
against write_atomic() which is synchronized only via the
console context ownership.
The device_lock() serializes acquiring the console context with
NBCON_PRIO_NORMAL. It is needed in case the device_lock() does
not disable preemption. It prevents the following race:
CPU0 CPU1
[ task A ]
nbcon_context_try_acquire()
# success with NORMAL prio
# .unsafe == false; // safe for takeover
[ schedule: task A -> B ]
WARN_ON()
nbcon_atomic_flush_pending()
nbcon_context_try_acquire()
# success with EMERGENCY prio
# flushing
nbcon_context_release()
# HERE: con->nbcon_state is free
# to take by anyone !!!
nbcon_context_try_acquire()
# success with NORMAL prio [ task B ]
[ schedule: task B -> A ]
nbcon_enter_unsafe()
nbcon_context_can_proceed()
BUG: nbcon_context_can_proceed() returns "true" because
the console is owned by a context on CPU0 with
NBCON_PRIO_NORMAL.
But it should return "false". The console is owned
by a context from task B and we do the check
in a context from task A.
Note that with these changes, the printer kthreads do not yet
take over full responsibility for nbcon printing during normal
operation. These changes only focus on the lifecycle of the
kthreads.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-7-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-04 14:11:25 +02:06
|
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2005-04-16 15:20:36 -07:00
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2024-01-22 12:03:46 +01:00
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2005-04-16 15:20:36 -07:00
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2007-02-10 01:45:02 -08:00
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2018-06-28 15:20:30 +02:00
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2005-04-16 15:20:36 -07:00
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2016-10-03 11:18:33 +02:00
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2020-06-15 09:48:34 +02:00
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2016-06-23 13:34:26 +02:00
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2024-01-22 12:03:59 +01:00
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2024-01-22 12:03:34 +01:00
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2024-01-22 12:03:59 +01:00
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2024-01-22 12:03:35 +01:00
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2024-01-22 12:03:39 +01:00
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2024-01-22 12:03:40 +01:00
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2024-01-22 12:03:43 +01:00
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2016-10-03 11:18:33 +02:00
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2024-01-22 12:03:44 +01:00
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2024-01-22 12:03:49 +01:00
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2024-01-22 12:03:59 +01:00
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2016-06-23 13:34:26 +02:00
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2024-01-22 12:03:52 +01:00
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2024-01-22 12:03:59 +01:00
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2016-06-23 13:34:26 +02:00
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2005-04-16 15:20:36 -07:00
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2024-01-22 12:03:34 +01:00
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2018-02-26 16:04:19 -08:00
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2024-01-22 12:03:35 +01:00
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2024-01-22 12:03:39 +01:00
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2024-01-22 12:03:40 +01:00
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2024-01-22 12:03:43 +01:00
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2018-02-26 16:04:19 -08:00
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2016-10-03 11:18:33 +02:00
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2024-01-22 12:03:44 +01:00
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2024-01-22 12:03:49 +01:00
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2024-01-22 12:03:50 +01:00
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2023-01-19 16:19:15 +01:00
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2018-02-26 16:04:19 -08:00
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2024-01-22 12:03:51 +01:00
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2018-02-26 16:04:19 -08:00
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2024-01-22 12:03:21 +01:00
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2018-02-26 16:04:19 -08:00
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2016-06-23 13:34:27 +02:00
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2018-02-26 16:04:19 -08:00
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2024-01-22 12:03:52 +01:00
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2018-02-26 16:04:19 -08:00
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2020-06-15 09:48:34 +02:00
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2020-06-15 09:48:35 +02:00
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2018-02-26 16:04:19 -08:00
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2024-01-22 12:03:33 +01:00
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2005-04-16 15:20:36 -07:00
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2023-10-09 23:18:41 +02:00
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[PATCH] VT binding: Add binding/unbinding support for the VT console
The framebuffer console is now able to dynamically bind and unbind from the VT
console layer. Due to the way the VT console layer works, the drivers
themselves decide when to bind or unbind. However, it was decided that
binding must be controlled, not by the drivers themselves, but by the VT
console layer. With this, dynamic binding is possible for all VT console
drivers, not just fbcon.
Thus, the VT console layer will impose the following to all VT console
drivers:
- all registered VT console drivers will be entered in a private list
- drivers can register themselves to the VT console layer, but they cannot
decide when to bind or unbind. (Exception: To maintain backwards
compatibility, take_over_console() will automatically bind the driver after
registration.)
- drivers can remove themselves from the list by unregistering from the VT
console layer. A prerequisite for unregistration is that the driver must not
be bound.
The following functions are new in the vt.c:
register_con_driver() - public function, this function adds the VT console
driver to an internal list maintained by the VT console
bind_con_driver() - private function, it binds the driver to the console
take_over_console() is changed to call register_con_driver() followed by a
bind_con_driver(). This is the only time drivers can decide when to bind to
the VT layer. This is to maintain backwards compatibility.
unbind_con_driver() - private function, it unbinds the driver from its
console. The vacated consoles will be taken over by the default boot console
driver.
unregister_con_driver() - public function, removes the driver from the
internal list maintained by the VT console. It will only succeed if the
driver is currently unbound.
con_is_bound() checks if the driver is currently bound or not
give_up_console() is just a wrapper to unregister_con_driver().
There are also 3 additional functions meant to be called only by the tty layer
for sysfs control:
vt_bind() - calls bind_con_driver()
vt_unbind() - calls unbind_con_driver()
vt_show_drivers() - shows the list of registered drivers
Most VT console drivers will continue to work as is, but might have problems
when unbinding or binding which should be fixable with minimal changes.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 00:27:08 -07:00
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2013-01-25 10:28:18 +10:00
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2013-01-25 10:28:15 +10:00
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2005-04-16 15:20:36 -07:00
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2024-01-08 14:41:02 +01:00
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2024-01-22 12:03:33 +01:00
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2010-08-06 15:36:47 -05:00
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2024-01-22 12:03:33 +01:00
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2010-08-06 15:36:47 -05:00
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2010-08-05 09:22:30 -05:00
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2005-04-16 15:20:36 -07:00
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2023-01-09 11:13:54 +01:06
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2024-01-22 12:04:00 +01:00
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2023-01-09 11:13:54 +01:06
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2023-07-17 21:52:06 +02:06
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2023-09-16 21:26:00 +02:06
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2023-01-09 11:13:54 +01:06
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2023-07-17 21:52:06 +02:06
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2023-09-16 21:26:00 +02:06
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2023-01-09 11:13:54 +01:06
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2005-04-16 15:20:36 -07:00
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2023-09-16 21:26:00 +02:06
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:00 +02:06
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:00 +02:06
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:00 +02:06
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2023-09-16 21:26:01 +02:06
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2024-01-22 12:04:00 +01:00
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:03 +02:06
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:06 +02:06
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2023-09-16 21:26:03 +02:06
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2023-09-16 21:26:05 +02:06
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:03 +02:06
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2023-09-16 21:26:06 +02:06
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2023-09-16 21:26:03 +02:06
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2023-09-16 21:26:05 +02:06
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2023-09-16 21:26:01 +02:06
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2023-09-16 21:26:06 +02:06
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2023-01-09 11:13:55 +01:06
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2024-08-20 08:35:33 +02:06
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2023-01-09 11:13:55 +01:06
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2023-09-16 21:26:00 +02:06
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2023-09-16 21:26:05 +02:06
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2024-08-20 08:35:39 +02:06
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2024-09-04 14:11:30 +02:06
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2023-09-16 21:26:03 +02:06
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printk: nbcon: Introduce printer kthreads
Provide the main implementation for running a printer kthread
per nbcon console that is takeover/handover aware. This
includes:
- new mandatory write_thread() callback
- kthread creation
- kthread main printing loop
- kthread wakeup mechanism
- kthread shutdown
kthread creation is a bit tricky because consoles may register
before kthreads can be created. In such cases, registration
will succeed, even though no kthread exists. Once kthreads can
be created, an early_initcall will set @printk_kthreads_ready.
If there are no registered boot consoles, the early_initcall
creates the kthreads for all registered nbcon consoles. If
kthread creation fails, the related console is unregistered.
If there are registered boot consoles when
@printk_kthreads_ready is set, no kthreads are created until
the final boot console unregisters.
Once kthread creation finally occurs, @printk_kthreads_running
is set so that the system knows kthreads are available for all
registered nbcon consoles.
If @printk_kthreads_running is already set when the console
is registering, the kthread is created during registration. If
kthread creation fails, the registration will fail.
Until @printk_kthreads_running is set, console printing occurs
directly via the console_lock.
kthread shutdown on system shutdown/reboot is necessary to
ensure the printer kthreads finish their printing so that the
system can cleanly transition back to direct printing via the
console_lock in order to reliably push out the final
shutdown/reboot messages. @printk_kthreads_running is cleared
before shutting down the individual kthreads.
The kthread uses a new mandatory write_thread() callback that
is called with both device_lock() and the console context
acquired.
The console ownership handling is necessary for synchronization
against write_atomic() which is synchronized only via the
console context ownership.
The device_lock() serializes acquiring the console context with
NBCON_PRIO_NORMAL. It is needed in case the device_lock() does
not disable preemption. It prevents the following race:
CPU0 CPU1
[ task A ]
nbcon_context_try_acquire()
# success with NORMAL prio
# .unsafe == false; // safe for takeover
[ schedule: task A -> B ]
WARN_ON()
nbcon_atomic_flush_pending()
nbcon_context_try_acquire()
# success with EMERGENCY prio
# flushing
nbcon_context_release()
# HERE: con->nbcon_state is free
# to take by anyone !!!
nbcon_context_try_acquire()
# success with NORMAL prio [ task B ]
[ schedule: task B -> A ]
nbcon_enter_unsafe()
nbcon_context_can_proceed()
BUG: nbcon_context_can_proceed() returns "true" because
the console is owned by a context on CPU0 with
NBCON_PRIO_NORMAL.
But it should return "false". The console is owned
by a context from task B and we do the check
in a context from task A.
Note that with these changes, the printer kthreads do not yet
take over full responsibility for nbcon printing during normal
operation. These changes only focus on the lifecycle of the
kthreads.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-7-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-04 14:11:25 +02:06
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2023-01-09 11:13:55 +01:06
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2007-05-08 00:26:47 -07:00
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2023-01-09 11:13:55 +01:06
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2023-09-16 21:26:00 +02:06
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2024-08-20 08:35:33 +02:06
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2024-09-04 14:11:20 +02:06
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2024-08-20 08:35:33 +02:06
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printk: nbcon: Introduce printer kthreads
Provide the main implementation for running a printer kthread
per nbcon console that is takeover/handover aware. This
includes:
- new mandatory write_thread() callback
- kthread creation
- kthread main printing loop
- kthread wakeup mechanism
- kthread shutdown
kthread creation is a bit tricky because consoles may register
before kthreads can be created. In such cases, registration
will succeed, even though no kthread exists. Once kthreads can
be created, an early_initcall will set @printk_kthreads_ready.
If there are no registered boot consoles, the early_initcall
creates the kthreads for all registered nbcon consoles. If
kthread creation fails, the related console is unregistered.
If there are registered boot consoles when
@printk_kthreads_ready is set, no kthreads are created until
the final boot console unregisters.
Once kthread creation finally occurs, @printk_kthreads_running
is set so that the system knows kthreads are available for all
registered nbcon consoles.
If @printk_kthreads_running is already set when the console
is registering, the kthread is created during registration. If
kthread creation fails, the registration will fail.
Until @printk_kthreads_running is set, console printing occurs
directly via the console_lock.
kthread shutdown on system shutdown/reboot is necessary to
ensure the printer kthreads finish their printing so that the
system can cleanly transition back to direct printing via the
console_lock in order to reliably push out the final
shutdown/reboot messages. @printk_kthreads_running is cleared
before shutting down the individual kthreads.
The kthread uses a new mandatory write_thread() callback that
is called with both device_lock() and the console context
acquired.
The console ownership handling is necessary for synchronization
against write_atomic() which is synchronized only via the
console context ownership.
The device_lock() serializes acquiring the console context with
NBCON_PRIO_NORMAL. It is needed in case the device_lock() does
not disable preemption. It prevents the following race:
CPU0 CPU1
[ task A ]
nbcon_context_try_acquire()
# success with NORMAL prio
# .unsafe == false; // safe for takeover
[ schedule: task A -> B ]
WARN_ON()
nbcon_atomic_flush_pending()
nbcon_context_try_acquire()
# success with EMERGENCY prio
# flushing
nbcon_context_release()
# HERE: con->nbcon_state is free
# to take by anyone !!!
nbcon_context_try_acquire()
# success with NORMAL prio [ task B ]
[ schedule: task B -> A ]
nbcon_enter_unsafe()
nbcon_context_can_proceed()
BUG: nbcon_context_can_proceed() returns "true" because
the console is owned by a context on CPU0 with
NBCON_PRIO_NORMAL.
But it should return "false". The console is owned
by a context from task B and we do the check
in a context from task A.
Note that with these changes, the printer kthreads do not yet
take over full responsibility for nbcon printing during normal
operation. These changes only focus on the lifecycle of the
kthreads.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-7-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-04 14:11:25 +02:06
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2024-08-20 08:35:34 +02:06
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2023-09-16 21:26:00 +02:06
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2023-09-16 21:26:05 +02:06
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2024-08-20 08:35:39 +02:06
|
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|
2024-09-04 14:11:30 +02:06
|
|
|
|
printk: nbcon: Introduce printer kthreads
Provide the main implementation for running a printer kthread
per nbcon console that is takeover/handover aware. This
includes:
- new mandatory write_thread() callback
- kthread creation
- kthread main printing loop
- kthread wakeup mechanism
- kthread shutdown
kthread creation is a bit tricky because consoles may register
before kthreads can be created. In such cases, registration
will succeed, even though no kthread exists. Once kthreads can
be created, an early_initcall will set @printk_kthreads_ready.
If there are no registered boot consoles, the early_initcall
creates the kthreads for all registered nbcon consoles. If
kthread creation fails, the related console is unregistered.
If there are registered boot consoles when
@printk_kthreads_ready is set, no kthreads are created until
the final boot console unregisters.
Once kthread creation finally occurs, @printk_kthreads_running
is set so that the system knows kthreads are available for all
registered nbcon consoles.
If @printk_kthreads_running is already set when the console
is registering, the kthread is created during registration. If
kthread creation fails, the registration will fail.
Until @printk_kthreads_running is set, console printing occurs
directly via the console_lock.
kthread shutdown on system shutdown/reboot is necessary to
ensure the printer kthreads finish their printing so that the
system can cleanly transition back to direct printing via the
console_lock in order to reliably push out the final
shutdown/reboot messages. @printk_kthreads_running is cleared
before shutting down the individual kthreads.
The kthread uses a new mandatory write_thread() callback that
is called with both device_lock() and the console context
acquired.
The console ownership handling is necessary for synchronization
against write_atomic() which is synchronized only via the
console context ownership.
The device_lock() serializes acquiring the console context with
NBCON_PRIO_NORMAL. It is needed in case the device_lock() does
not disable preemption. It prevents the following race:
CPU0 CPU1
[ task A ]
nbcon_context_try_acquire()
# success with NORMAL prio
# .unsafe == false; // safe for takeover
[ schedule: task A -> B ]
WARN_ON()
nbcon_atomic_flush_pending()
nbcon_context_try_acquire()
# success with EMERGENCY prio
# flushing
nbcon_context_release()
# HERE: con->nbcon_state is free
# to take by anyone !!!
nbcon_context_try_acquire()
# success with NORMAL prio [ task B ]
[ schedule: task B -> A ]
nbcon_enter_unsafe()
nbcon_context_can_proceed()
BUG: nbcon_context_can_proceed() returns "true" because
the console is owned by a context on CPU0 with
NBCON_PRIO_NORMAL.
But it should return "false". The console is owned
by a context from task B and we do the check
in a context from task A.
Note that with these changes, the printer kthreads do not yet
take over full responsibility for nbcon printing during normal
operation. These changes only focus on the lifecycle of the
kthreads.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-7-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-04 14:11:25 +02:06
|
|
|
|
2023-09-16 21:26:03 +02:06
|
|
|
|
printk: nbcon: Introduce printer kthreads
Provide the main implementation for running a printer kthread
per nbcon console that is takeover/handover aware. This
includes:
- new mandatory write_thread() callback
- kthread creation
- kthread main printing loop
- kthread wakeup mechanism
- kthread shutdown
kthread creation is a bit tricky because consoles may register
before kthreads can be created. In such cases, registration
will succeed, even though no kthread exists. Once kthreads can
be created, an early_initcall will set @printk_kthreads_ready.
If there are no registered boot consoles, the early_initcall
creates the kthreads for all registered nbcon consoles. If
kthread creation fails, the related console is unregistered.
If there are registered boot consoles when
@printk_kthreads_ready is set, no kthreads are created until
the final boot console unregisters.
Once kthread creation finally occurs, @printk_kthreads_running
is set so that the system knows kthreads are available for all
registered nbcon consoles.
If @printk_kthreads_running is already set when the console
is registering, the kthread is created during registration. If
kthread creation fails, the registration will fail.
Until @printk_kthreads_running is set, console printing occurs
directly via the console_lock.
kthread shutdown on system shutdown/reboot is necessary to
ensure the printer kthreads finish their printing so that the
system can cleanly transition back to direct printing via the
console_lock in order to reliably push out the final
shutdown/reboot messages. @printk_kthreads_running is cleared
before shutting down the individual kthreads.
The kthread uses a new mandatory write_thread() callback that
is called with both device_lock() and the console context
acquired.
The console ownership handling is necessary for synchronization
against write_atomic() which is synchronized only via the
console context ownership.
The device_lock() serializes acquiring the console context with
NBCON_PRIO_NORMAL. It is needed in case the device_lock() does
not disable preemption. It prevents the following race:
CPU0 CPU1
[ task A ]
nbcon_context_try_acquire()
# success with NORMAL prio
# .unsafe == false; // safe for takeover
[ schedule: task A -> B ]
WARN_ON()
nbcon_atomic_flush_pending()
nbcon_context_try_acquire()
# success with EMERGENCY prio
# flushing
nbcon_context_release()
# HERE: con->nbcon_state is free
# to take by anyone !!!
nbcon_context_try_acquire()
# success with NORMAL prio [ task B ]
[ schedule: task B -> A ]
nbcon_enter_unsafe()
nbcon_context_can_proceed()
BUG: nbcon_context_can_proceed() returns "true" because
the console is owned by a context on CPU0 with
NBCON_PRIO_NORMAL.
But it should return "false". The console is owned
by a context from task B and we do the check
in a context from task A.
Note that with these changes, the printer kthreads do not yet
take over full responsibility for nbcon printing during normal
operation. These changes only focus on the lifecycle of the
kthreads.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-7-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-04 14:11:25 +02:06
|
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|
2005-04-16 15:20:36 -07:00
|
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2022-11-21 12:16:12 +01:06
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2022-11-16 17:27:15 +01:06
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2022-11-21 12:16:12 +01:06
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2022-11-16 17:27:14 +01:06
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2022-11-16 17:27:24 +01:06
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2024-08-20 08:35:38 +02:06
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2022-11-16 17:27:24 +01:06
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2024-08-20 08:35:38 +02:06
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2022-11-16 17:27:24 +01:06
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2024-08-20 08:35:38 +02:06
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2022-11-16 17:27:24 +01:06
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2024-08-20 08:35:38 +02:06
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2022-11-16 17:27:24 +01:06
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2024-08-20 08:35:38 +02:06
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2022-11-16 17:27:24 +01:06
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2022-11-16 17:27:33 +01:06
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2022-11-16 17:27:15 +01:06
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2022-11-21 12:16:12 +01:06
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2024-01-22 12:04:00 +01:00
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2022-11-21 12:16:12 +01:06
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2010-11-04 16:20:20 +01:00
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2022-11-21 12:16:12 +01:06
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2022-11-16 17:27:14 +01:06
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2010-11-04 16:20:20 +01:00
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2023-09-16 21:26:07 +02:06
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2024-08-20 08:35:57 +02:06
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2023-09-16 21:26:07 +02:06
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2024-09-04 14:11:20 +02:06
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2023-09-16 21:26:07 +02:06
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2024-08-20 08:35:57 +02:06
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2023-09-16 21:26:07 +02:06
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2024-09-04 14:11:20 +02:06
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2023-09-16 21:26:07 +02:06
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xen: Enable console tty by default in domU if it's not a dummy
Without console= arguments on the kernel command line, the first
console to register becomes enabled and the preferred console (the one
behind /dev/console). This is normally tty (assuming
CONFIG_VT_CONSOLE is enabled, which it commonly is).
This is okay as long tty is a useful console. But unless we have the
PV framebuffer, and it is enabled for this domain, tty0 in domU is
merely a dummy. In that case, we want the preferred console to be the
Xen console hvc0, and we want it without having to fiddle with the
kernel command line. Commit b8c2d3dfbc117dff26058fbac316b8acfc2cb5f7
did that for us.
Since we now have the PV framebuffer, we want to enable and prefer tty
again, but only when PVFB is enabled. But even then we still want to
enable the Xen console as well.
Problem: when tty registers, we can't yet know whether the PVFB is
enabled. By the time we can know (xenstore is up), the console setup
game is over.
Solution: enable console tty by default, but keep hvc as the preferred
console. Change the preferred console to tty when PVFB probes
successfully, unless we've been given console kernel parameters.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-26 23:31:07 +01:00
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2013-04-29 16:17:18 -07:00
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xen: Enable console tty by default in domU if it's not a dummy
Without console= arguments on the kernel command line, the first
console to register becomes enabled and the preferred console (the one
behind /dev/console). This is normally tty (assuming
CONFIG_VT_CONSOLE is enabled, which it commonly is).
This is okay as long tty is a useful console. But unless we have the
PV framebuffer, and it is enabled for this domain, tty0 in domU is
merely a dummy. In that case, we want the preferred console to be the
Xen console hvc0, and we want it without having to fiddle with the
kernel command line. Commit b8c2d3dfbc117dff26058fbac316b8acfc2cb5f7
did that for us.
Since we now have the PV framebuffer, we want to enable and prefer tty
again, but only when PVFB is enabled. But even then we still want to
enable the Xen console as well.
Problem: when tty registers, we can't yet know whether the PVFB is
enabled. By the time we can know (xenstore is up), the console setup
game is over.
Solution: enable console tty by default, but keep hvc as the preferred
console. Change the preferred console to tty when PVFB probes
successfully, unless we've been given console kernel parameters.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-26 23:31:07 +01:00
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2019-05-17 14:31:50 -07:00
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2023-10-12 09:42:57 +03:00
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2022-11-16 17:27:44 +01:06
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2005-04-16 15:20:36 -07:00
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2011-01-25 15:07:35 -08:00
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2005-04-16 15:20:36 -07:00
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2019-05-17 14:31:50 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-30 00:54:51 -07:00
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2013-01-17 22:44:22 -08:00
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2010-12-01 18:51:05 +01:00
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2013-01-17 22:44:22 -08:00
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2012-01-13 09:32:20 +10:30
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2007-10-18 03:04:50 -07:00
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2006-06-19 18:16:01 -07:00
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2006-10-03 01:15:06 -07:00
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2009-03-09 14:18:52 +01:00
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2007-02-10 01:45:02 -08:00
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2005-04-16 15:20:36 -07:00
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2018-07-31 13:06:57 +02:00
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2005-04-16 15:20:36 -07:00
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2017-04-12 18:37:14 -04:00
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2018-06-28 15:20:30 +02:00
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2005-04-16 15:20:36 -07:00
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