Hi, This is v8 of a series to wire up the nbcon consoles so that they actually perform printing using their write_atomic() callback. v7 is here [0]. For information about the motivation of the atomic consoles, please read the cover letter of v1 [1]. The main focus of this series: - For nbcon consoles, always call write_atomic() directly from printk() caller context for the panic CPU. - For nbcon consoles, call write_atomic() when unlocking the console lock. - Only perform the console lock/unlock dance if legacy or boot consoles are registered. - For legacy consoles, if nbcon consoles are registered, do not attempt to print from printk() caller context for the panic CPU until nbcon consoles have had a chance to print the most significant messages. - Mark emergency sections. In these sections, every printk() call will attempt to directly flush to the consoles using the EMERGENCY priority. This series does _not_ include threaded printing or nbcon drivers. Those features will be added in separate follow-up series. The changes since v7: - Change printk_get_console_flush_type() to set preferred flush types. - Change printk_get_console_flush_type() to also check for legacy consoles before seting @legacy_direct. - Change vprintk_emit() to hack the struct console_flush_type for LOGLEVEL_SCHED rather than using local variables. - Change console_cpu_notify() to also flush nbcon atomic consoles. - Remove unnecessary flush type check in nbcon_atomic_flush_pending_con(). It is not needed until the threaded series. - Fix compiling issues related to @legacy_allow_panic_sync for !CONFIG_PRINTK. John Ogness [0] https://lore.kernel.org/lkml/20240804005138.3722656-1-john.ogness@xxxxxxxxxxxxx [1] https://lore.kernel.org/lkml/20230302195618.156940-1-john.ogness@xxxxxxxxxxxxx John Ogness (30): printk: Add notation to console_srcu locking printk: nbcon: Consolidate alloc() and init() printk: nbcon: Clarify rules of the owner/waiter matching printk: nbcon: Remove return value for write_atomic() printk: nbcon: Add detailed doc for write_atomic() printk: nbcon: Add callbacks to synchronize with driver printk: nbcon: Use driver synchronization while (un)registering serial: core: Provide low-level functions to lock port serial: core: Introduce wrapper to set @uart_port->cons console: Improve console_srcu_read_flags() comments nbcon: Add API to acquire context for non-printing operations serial: core: Acquire nbcon context in port->lock wrapper printk: nbcon: Do not rely on proxy headers printk: Make console_is_usable() available to nbcon.c printk: Let console_is_usable() handle nbcon printk: Add @flags argument for console_is_usable() printk: nbcon: Add helper to assign priority based on CPU state printk: Track registered boot consoles printk: nbcon: Use nbcon consoles in console_flush_all() printk: Add is_printk_legacy_deferred() printk: nbcon: Flush new records on device_release() printk: Flush nbcon consoles first on panic printk: nbcon: Add unsafe flushing on panic printk: Avoid console_lock dance if no legacy or boot consoles printk: Track nbcon consoles printk: Coordinate direct printing in panic printk: Add helper for flush type logic panic: Mark emergency section in oops rcu: Mark emergency sections in rcu stalls lockdep: Mark emergency sections in lockdep splats Petr Mladek (1): printk: Properly deal with nbcon consoles on seq init Sebastian Andrzej Siewior (1): printk: Check printk_deferred_enter()/_exit() usage Thomas Gleixner (3): printk: nbcon: Provide function to flush using write_atomic() printk: nbcon: Implement emergency sections panic: Mark emergency section in warn drivers/tty/serial/8250/8250_core.c | 6 +- drivers/tty/serial/amba-pl011.c | 2 +- drivers/tty/serial/serial_core.c | 16 +- include/linux/console.h | 110 +++++- include/linux/printk.h | 33 +- include/linux/serial_core.h | 117 +++++- kernel/locking/lockdep.c | 83 ++++- kernel/panic.c | 9 + kernel/printk/internal.h | 137 ++++++- kernel/printk/nbcon.c | 556 +++++++++++++++++++++++++--- kernel/printk/printk.c | 251 ++++++++++--- kernel/printk/printk_ringbuffer.h | 2 + kernel/printk/printk_safe.c | 23 +- kernel/rcu/tree_exp.h | 7 + kernel/rcu/tree_stall.h | 9 + 15 files changed, 1210 insertions(+), 151 deletions(-) base-commit: bcc954c6caba01fca143162d5fbb90e46aa1ad80 -- 2.39.2
