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From: John Ogness <john.ogness@linutronix.de>
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 <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 | 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;
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