From: John Ogness Date: Thu, 14 Dec 2023 14:38:42 +0000 Subject: [PATCH 23/48] printk: nbcon: Assign priority based on CPU state Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz Use the current state of the CPU to determine which priority to assign to the printing context. The EMERGENCY priority handling is added in a follow-up commit. It will use a per-CPU variable. Note: nbcon_driver_acquire(), which is used by console drivers to acquire the nbcon console for non-printing activities, will always use NORMAL priority. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Signed-off-by: Sebastian Andrzej Siewior --- kernel/printk/internal.h | 2 ++ kernel/printk/nbcon.c | 20 ++++++++++++++++++-- 2 files changed, 20 insertions(+), 2 deletions(-) --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -86,6 +86,7 @@ void nbcon_seq_force(struct console *con bool nbcon_alloc(struct console *con); void nbcon_init(struct console *con); void nbcon_free(struct console *con); +enum nbcon_prio nbcon_get_default_prio(void); void nbcon_atomic_flush_pending(void); bool nbcon_legacy_emit_next_record(struct console *con, bool *handover, int cookie); @@ -143,6 +144,7 @@ static inline void nbcon_seq_force(struc static inline bool nbcon_alloc(struct console *con) { return false; } static inline void nbcon_init(struct console *con) { } static inline void nbcon_free(struct console *con) { } +static inline enum nbcon_prio nbcon_get_default_prio(void) { return NBCON_PRIO_NONE; } static inline void nbcon_atomic_flush_pending(void) { } static inline bool nbcon_legacy_emit_next_record(struct console *con, bool *handover, int cookie) { return false; } --- a/kernel/printk/nbcon.c +++ b/kernel/printk/nbcon.c @@ -968,6 +968,22 @@ static bool nbcon_atomic_emit_one(struct } /** + * nbcon_get_default_prio - The appropriate nbcon priority to use for nbcon + * printing on the current CPU + * + * Context: Any context which could not be migrated to another CPU. + * Return: The nbcon_prio to use for acquiring an nbcon console in this + * context for printing. + */ +enum nbcon_prio nbcon_get_default_prio(void) +{ + if (this_cpu_in_panic()) + return NBCON_PRIO_PANIC; + + return NBCON_PRIO_NORMAL; +} + +/** * nbcon_legacy_emit_next_record - Print one record for an nbcon console * in legacy contexts * @con: The console to print on @@ -1001,7 +1017,7 @@ bool nbcon_legacy_emit_next_record(struc stop_critical_timings(); ctxt->console = con; - ctxt->prio = NBCON_PRIO_NORMAL; + ctxt->prio = nbcon_get_default_prio(); progress = nbcon_atomic_emit_one(&wctxt); @@ -1032,7 +1048,7 @@ static bool __nbcon_atomic_flush_pending ctxt->console = con; ctxt->spinwait_max_us = 2000; - ctxt->prio = NBCON_PRIO_NORMAL; + ctxt->prio = nbcon_get_default_prio(); if (!nbcon_context_try_acquire(ctxt)) return false;