kernel/linux.git/include/linux/printk.h, branch v6.19.11

panic/printk: replace this_cpu_in_panic() with panic_on_this_cpu()

2025-09-14T00:32:52+00:00

The helper this_cpu_in_panic() duplicated logic already provided by panic_on_this_cpu(). Remove this_cpu_in_panic() and switch all users to panic_on_this_cpu(). This simplifies the code and avoids having two helpers for the same check. Link: https://lkml.kernel.org/r/20250825022947.1596226-8-wangjinchao600@gmail.com Signed-off-by: Jinchao Wang Cc: Anna Schumaker Cc: Baoquan He Cc: "Darrick J. Wong" Cc: Dave Young Cc: Doug Anderson Cc: "Guilherme G. Piccoli" Cc: Helge Deller Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Joanthan Cameron Cc: Joel Granados Cc: John Ogness Cc: Kees Cook Cc: Li Huafei Cc: "Luck, Tony" Cc: Luo Gengkun Cc: Max Kellermann Cc: Nam Cao Cc: oushixiong Cc: Petr Mladek Cc: Qianqiang Liu Cc: Sergey Senozhatsky Cc: Sohil Mehta Cc: Steven Rostedt Cc: Tejun Heo Cc: Thomas Gleinxer Cc: Thomas Zimemrmann Cc: Thorsten Blum Cc: Ville Syrjala Cc: Vivek Goyal Cc: Yicong Yang Cc: Yunhui Cui Cc: Yury Norov (NVIDIA) Signed-off-by: Andrew Morton

printk: Make vprintk_deferred() public

2025-07-09T19:27:00+00:00

vprintk_deferred() is useful for implementing runtime verification reactors. Make it public. Signed-off-by: Nam Cao Reviewed-by: Petr Mladek Signed-off-by: Steven Rostedt (Google)

Flush console log from kernel_power_off()

2025-03-05T02:44:29+00:00

Kernels built with CONFIG_PREEMPT_RT=y can lose significant console output and shutdown time, which hides shutdown-time RCU issues from rcutorture. Therefore, make pr_flush() public and invoke it after then last print in kernel_power_off(). [ paulmck: Apply John Ogness feedback. ] [ paulmck: Appy Sebastian Andrzej Siewior feedback. ] [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Paul E. McKenney Reviewed-by: John Ogness Reviewed-by: Petr Mladek Cc: Steven Rostedt Cc: Sergey Senozhatsky Link: https://lore.kernel.org/r/5f743488-dc2a-4f19-bdda-cf50b9314832@paulmck-laptop Signed-off-by: Boqun Feng

printk: add dummy printk_force_console_enter/exit helpers

2024-11-13T10:00:23+00:00

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

2024-11-11T11:53:31+00:00

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

2024-08-21T12:56:25+00:00

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

2024-08-21T12:56:24+00:00

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

2024-08-21T12:56:23+00:00

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

2024-08-21T12:56:22+00:00

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

2024-07-25T20:18:41+00:00

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