this patchset does some clean up of the code for handling preferred
consoles in the console registration code.
+ 1st and 2nd patch try to improve some naming.
+ 3rd patch removes some code duplication. It better defines and
describes the rules for adding and updating preferred consoles.
It uses a more defensive coding style.
+ 4-8th patch improve handling of Braille consoles.
They are preferred via the command line but they do not get
printk() messages and are not associated with /dev/console.
The new code makes this more obvious. Also it explicitly
defines the relation against default consoles and other
non-Braille preferred consoles.
+ 9th patch removes a hidden side effect of
try_enable_preferred_console()
+ 10th patch prevents adding more side effectes to
try_enable_preferred_console(). It allows to call it
only when there are any non-Braille preferred consoles.
+ 11th patch allows to catch an error when enabling a console
driver by default.
This patchset is a prerequisite for Marcos' clean up of CON_ENABLE
flag handling. It should prevent regressions caused by the
hidden effects of try_enable_preferred_console(), for example,
see https://lore.kernel.org/r/89409a0f48e6998ff6dd2245691b9954f0e1e435.camel@suse.com
Also I am working on a feature which would allow to explicitly
enable/prefer consoles proposed by SPCR, device tree, or
platform-specific code using a generic "console=platform".
This clean up is a prerequisite, see
https://github.com/pmladek/linux/tree/console-platform-poc1-iter9
Changes against [v3]:
+ Move the handling of pre-enabled consoles into register_console()
as 1st patch. It prevents a possible invalid access. [Petr]
+ Move the code for handling pre-enabled to console to
try_enable_console() in 7th patch. The resulting code
is the same as in v3.
This 2nd move was not needed in v3 because the code
was moved to this final location later. [Petr]
+ Switch order of the 10th and 11th patch. Aka make
try_enable_default_console() return an err before
refactoring try_enable_console() call
try_enable_preferred_console() only when there is any.
[Petr]
+ Initialize err value in try_enable_console() in 11th patch.
It prevents using a non-initialized variable. [AI:gemini-3]
+ Make sure that pre-enabled consoles won't get registered
when something went wrong in try_enable_console()
in 11th patch [Petr]
Changes against [v2]:
+ Move static_assert() after declaration (1st patch) [Steven]
+ Rename update_preferred_console() to add_or_update_preferred_console() [John]
+ WARN_ON() when called without "name" and "devname" [John]
+ print error when reached MAX_PREFERRED_CONSOLES
+ Add comment above code adding new entries [John]
(all in 4th patch)
+ Call console->setup() under console_lock() in braille_register_console()
(new patch) [Sashiko]
+ Use "No functional changes." phrase in commit messages. [Steven]
+ Call try_enable_preferred_console() only when there is no
preferred console (reworked and split 9th patch) [Petr]
+ Added taken Reviewed-by and Acked-by tags [John, Macros]
Changes against [v1]:
+ Fix stale comment (1st patch, Chris)
+ Add comment descibing update_preferred_console() behavior (3rd patch, John)
+ Better describe behavior changes caused by update_preferred_console()
in the commit message (3rd patch, Chris)
+ Use unsigned int for iterating/indexing preferred_consoles[]
table (3rd patch, John)
+ Add a check preventing an update via "devname" is already assigned
to a real "name". (3rd patch, Petr)
+ Use only Braille entries when trying to enable Braille console (Chris)
+ Split all try_enable_*console() calls into new try_enable_console()
and return early when try_enable_braille_console() succeeded.
Note that we do not longer need to initialize "err" variable
in this case. (new 5th patch, Chris, Petr)
+ Put back the explicit check of CON_BRL flag in register_console()
so that it returns prelimitary only when the driver is used in Braille
mode. (6th patch, Chris, Petr)
+ Add comments explaining that try_enable_braille_console() might succeeded
also when newcon->match() succeeded. In this case, the Braille mode can't
be used because the console device was already used as an early console.[*]
(6th patch, Chris, Petr)
+ Reset preferred_dev_console_prev when used to revert the value.
(7th patch, John)
+ Add Acked-by and Reviewed-by tags (1st, 2nd, 4th patch, Chris, Marcos)
[*] This is a questional behavior. I would personally prefer when
the early console is unregistered at this point and the console
device is converted into Braille console. I consider the Braille
mode more important. But it might be changed/fixed later
in another patchset.
[v1] https://lore.kernel.org/r/20260206165002.496724-1-pmladek@suse.com
[v2] https://lore.kernel.org/r/20260423130015.85175-1-pmladek@suse.com
[v3] https://lore.kernel.org/r/20260602085312.228251-1-pmladek@suse.com
Petr Mladek (11):
printk: Handle pre-enabled consoles in the top-level
register_console()
printk: Rename struct console_cmdline to preferred_console
printk: Rename preferred_console to preferred_dev_console
printk: Separate code for adding/updating preferred console metadata
printk: Cleanup _braille_(un)register_console() wrappers
console/braille: Lock console->setup() call during the registration
printk: Separate code for enabling console
printk: Try to register each console as Braille first
printk: Do not set Braille console as preferred_console
printk: Modify try_enable_default_console() to return error/success
printk: Try enable preferred consoles only when there are any
.../accessibility/braille/braille_console.c | 9 +-
kernel/printk/braille.c | 20 +-
kernel/printk/braille.h | 23 +-
.../{console_cmdline.h => console_register.h} | 6 +-
kernel/printk/printk.c | 402 ++++++++++++------
5 files changed, 315 insertions(+), 145 deletions(-)
rename kernel/printk/{console_cmdline.h => console_register.h} (83%)
--
2.54.0