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From: John Ogness <john.ogness@linutronix.de>
Date: Thu, 14 Dec 2023 14:38:42 +0000
Subject: [PATCH 17/46] printk: nbcon: Add helper to assign priority based on
CPU state
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz
Add a helper function to 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_try_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 <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/printk/internal.h | 2 ++
kernel/printk/nbcon.c | 16 ++++++++++++++++
2 files changed, 18 insertions(+)
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -84,6 +84,7 @@ void nbcon_seq_force(struct console *con
bool nbcon_alloc(struct console *con);
void nbcon_init(struct console *con, u64 init_seq);
void nbcon_free(struct console *con);
+enum nbcon_prio nbcon_get_default_prio(void);
/*
* Check if the given console is currently capable and allowed to print
@@ -138,6 +139,7 @@ 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, u64 init_seq) { }
static inline void nbcon_free(struct console *con) { }
+static inline enum nbcon_prio nbcon_get_default_prio(void) { return NBCON_PRIO_NONE; }
static inline bool console_is_usable(struct console *con, short flags) { return false; }
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -938,6 +938,22 @@ static bool nbcon_emit_next_record(struc
}
/**
+ * 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_alloc - Allocate buffers needed by the nbcon console
* @con: Console to allocate buffers for
*
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