user/sven/linux.git/include/linux/printk.h, branch v6.13.5

printk: add dummy printk_force_console_enter/exit helpers

2024-11-13T10:00:23Z

The newly added interface is broken when PRINTK is disabled: drivers/tty/sysrq.c: In function '__handle_sysrq': drivers/tty/sysrq.c:601:9: error: implicit declaration of function 'printk_force_console_enter' [-Wimplicit-function-declaration] 601 | printk_force_console_enter(); | ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/tty/sysrq.c:611:25: error: implicit declaration of function 'printk_force_console_exit' [-Wimplicit-function-declaration] 611 | printk_force_console_exit(); | ^~~~~~~~~~~~~~~~~~~~~~~~~ Add empty stub functions for both. Fixes: ed76c07c6885 ("printk: Introduce FORCE_CON flag") Signed-off-by: Arnd Bergmann Reviewed-by: Andy Shevchenko Reviewed-by: Marcos Paulo de Souza Tested-by: Marcos Paulo de Souza Link: https://lore.kernel.org/r/20241112142939.724093-1-arnd@kernel.org Signed-off-by: Petr Mladek

printk: Introduce FORCE_CON flag

2024-11-11T11:53:31Z

Introduce FORCE_CON flag to printk. The new flag will make it possible to create a context where printk messages will never be suppressed. This mechanism will be used in the next patch to create a force_con context on sysrq handling, removing an existing workaround on the loglevel global variable. The workaround existed to make sure that sysrq header messages were sent to all consoles, but this doesn't work with deferred messages because the loglevel might be restored to its original value before a console flushes the messages. Signed-off-by: Marcos Paulo de Souza Reviewed-by: John Ogness Reviewed-by: Petr Mladek Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20241105-printk-loud-con-v2-1-bd3ecdf7b0e4@suse.com Signed-off-by: Petr Mladek

printk: Coordinate direct printing in panic

2024-08-21T12:56:25Z

If legacy and nbcon consoles are registered and the nbcon consoles are allowed to flush (i.e. no boot consoles registered), the legacy consoles will no longer perform direct printing on the panic CPU until after the backtrace has been stored. This will give the safe nbcon consoles a chance to print the panic messages before allowing the unsafe legacy consoles to print. If no nbcon consoles are registered or they are not allowed to flush because boot consoles are registered, there is no change in behavior (i.e. legacy consoles will always attempt to print from the printk() caller context). Signed-off-by: John Ogness Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20240820063001.36405-30-john.ogness@linutronix.de Signed-off-by: Petr Mladek

printk: nbcon: Add unsafe flushing on panic

2024-08-21T12:56:24Z

Add nbcon_atomic_flush_unsafe() to flush all nbcon consoles using the write_atomic() callback and allowing unsafe hostile takeovers. Call this at the end of panic() as a final attempt to flush any pending messages. Note that legacy consoles use unsafe methods for flushing from the beginning of panic (see bust_spinlocks()). Therefore, systems using both legacy and nbcon consoles may still fail to see panic messages due to unsafe legacy console usage. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20240820063001.36405-27-john.ogness@linutronix.de Signed-off-by: Petr Mladek

nbcon: Add API to acquire context for non-printing operations

2024-08-21T12:56:23Z

Provide functions nbcon_device_try_acquire() and nbcon_device_release() which will try to acquire the nbcon console ownership with NBCON_PRIO_NORMAL and mark it unsafe for handover/takeover. These functions are to be used together with the device-specific locking when performing non-printing activities on the console device. They will allow synchronization against the atomic_write() callback which will be serialized, for higher priority contexts, only by acquiring the console context ownership. Pitfalls: The API requires to be called in a context with migration disabled because it uses per-CPU variables internally. The context is set unsafe for a takeover all the time. It guarantees full serialization against any atomic_write() caller except for the final flush in panic() which might try an unsafe takeover. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20240820063001.36405-14-john.ogness@linutronix.de Signed-off-by: Petr Mladek

printk: Check printk_deferred_enter()/_exit() usage

2024-08-21T12:56:22Z

Add validation that printk_deferred_enter()/_exit() are called in non-migration contexts. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: John Ogness Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20240820063001.36405-5-john.ogness@linutronix.de Signed-off-by: Petr Mladek

Merge tag 'printk-for-6.11-trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2024-07-25T20:18:41Z

Pull printk updates from Petr Mladek: - trivial printk changes The bigger "real" printk work is still being discussed. * tag 'printk-for-6.11-trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: vsprintf: add missing MODULE_DESCRIPTION() macro printk: Rename console_replay_all() and update context

printk: Add match_devname_and_update_preferred_console()

2024-07-04T13:41:44Z

Let's add match_devname_and_update_preferred_console() for driver subsystems to call during init when the console is ready, and it's character device name is known. For now, we use it only for the serial layer to allow console=DEVNAME:0.0 style hardware based addressing for consoles. The earlier attempt on doing this caused a regression with the kernel command line console order as it added calling __add_preferred_console() again later on during init. A better approach was suggested by Petr where we add the deferred console to the console_cmdline[] and update it later on when the console is ready. Suggested-by: Petr Mladek Co-developed-by: Petr Mladek Signed-off-by: Tony Lindgren Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20240703100615.118762-2-tony.lindgren@linux.intel.com Signed-off-by: Greg Kroah-Hartman

Revert "printk: Save console options for add_preferred_console_match()"

2024-06-25T05:58:10Z

This reverts commit f03e8c1060f86c23eb49bafee99d9fcbd1c1bd77. Let's roll back all of the serial core and printk console changes that went into 6.10-rc1 as there still are problems with them that need to be sorted out. Link: https://lore.kernel.org/r/ZnpRozsdw6zbjqze@tlindgre-MOBL1 Reported-by: Petr Mladek Reported-by: Tony Lindgren Cc: Jiri Slaby Cc: John Ogness Cc: Sergey Senozhatsky Cc: Andy Shevchenko Cc: Ilpo Järvinen Signed-off-by: Greg Kroah-Hartman

printk: Rename console_replay_all() and update context

2024-06-03T15:17:29Z

Rename console_replay_all() to console_try_replay_all() to make clear that the implementation is best effort. Also, the function should not be called in NMI context as it takes locks, so update the comment in code. Fixes: 693f75b91a91 ("printk: Add function to replay kernel log on consoles") Fixes: 1b743485e27f ("tty/sysrq: Replay kernel log messages on consoles via sysrq") Suggested-by: Petr Mladek Signed-off-by: Shimoyashiki Taichi Signed-off-by: Sreenath Vijayan Link: https://lore.kernel.org/r/Zlguq/wU21Z8MqI4@sreenath.vijayan@sony.com Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek