kernel/linux.git/include/linux/printk.h, branch v6.12.80

Flush console log from kernel_power_off()

2025-04-20T08:15:12+00:00

[ Upstream commit 6ea9a1781c70a8be1fcdc49134fc1bf4baba8bca ] 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 Signed-off-by: Sasha Levin

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

printk: Add match_devname_and_update_preferred_console()

2024-07-04T13:41:44+00:00

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()"

2024-06-25T05:58:10+00:00

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

2024-06-03T15:17:29+00:00

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

Merge tag 'tty-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2024-05-22T18:53:02+00:00

Pull tty / serial updates from Greg KH: "Here is the big set of tty/serial driver changes for 6.10-rc1. Included in here are: - Usual good set of api cleanups and evolution by Jiri Slaby to make the serial interfaces move out of the 1990's by using kfifos instead of hand-rolling their own logic. - 8250_exar driver updates - max3100 driver updates - sc16is7xx driver updates - exar driver updates - sh-sci driver updates - tty ldisc api addition to help refuse bindings - other smaller serial driver updates All of these have been in linux-next for a while with no reported issues" * tag 'tty-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (113 commits) serial: Clear UPF_DEAD before calling tty_port_register_device_attr_serdev() serial: imx: Raise TX trigger level to 8 serial: 8250_pnp: Simplify "line" related code serial: sh-sci: simplify locking when re-issuing RXDMA fails serial: sh-sci: let timeout timer only run when DMA is scheduled serial: sh-sci: describe locking requirements for invalidating RXDMA serial: sh-sci: protect invalidating RXDMA on shutdown tty: add the option to have a tty reject a new ldisc serial: core: Call device_set_awake_path() for console port dt-bindings: serial: brcm,bcm2835-aux-uart: convert to dtschema tty: serial: uartps: Add support for uartps controller reset arm64: zynqmp: Add resets property for UART nodes dt-bindings: serial: cdns,uart: Add optional reset property serial: 8250_pnp: Switch to DEFINE_SIMPLE_DEV_PM_OPS() serial: 8250_exar: Keep the includes sorted serial: 8250_exar: Make type of bit the same in exar_ee_*_bit() serial: 8250_exar: Use BIT() in exar_ee_read() serial: 8250_exar: Switch to use dev_err_probe() serial: 8250_exar: Return directly from switch-cases serial: 8250_exar: Decrease indentation level ...