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Message-Id: <20240804005138.3722656-20-john.ogness@linutronix.de>
Date: Sun, 4 Aug 2024 02:57:22 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Petr Mladek <pmladek@...e.com>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH printk v7 19/35] printk: nbcon: Add helper to assign priority based on CPU state
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_device_try_acquire(), which is used by console
drivers to acquire the nbcon console for non-printing
activities, is hard-coded to always use NORMAL priority.
Signed-off-by: John Ogness <john.ogness@...utronix.de>
Reviewed-by: Petr Mladek <pmladek@...e.com>
---
kernel/printk/internal.h | 2 ++
kernel/printk/nbcon.c | 19 +++++++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index fe8d84d78f1c..72f229382cfa 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -83,6 +83,7 @@ u64 nbcon_seq_read(struct console *con);
void nbcon_seq_force(struct console *con, u64 seq);
bool nbcon_alloc(struct console *con);
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
@@ -136,6 +137,7 @@ static inline u64 nbcon_seq_read(struct console *con) { return 0; }
static inline void nbcon_seq_force(struct console *con, u64 seq) { }
static inline bool nbcon_alloc(struct console *con) { return false; }
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; }
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index e8ddcb6f7053..c6a9aa9f62f6 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -973,6 +973,25 @@ static bool nbcon_emit_next_record(struct nbcon_write_context *wctxt)
return nbcon_context_exit_unsafe(ctxt);
}
+/**
+ * nbcon_get_default_prio - The appropriate nbcon priority to use for nbcon
+ * printing on the current CPU
+ *
+ * Context: Any context.
+ * Return: The nbcon_prio to use for acquiring an nbcon console in this
+ * context for printing.
+ *
+ * The function is safe for reading per-CPU data in any context because
+ * preemption is disabled if the current CPU is in the panic state.
+ */
+enum nbcon_prio nbcon_get_default_prio(void)
+{
+ if (this_cpu_in_panic())
+ return NBCON_PRIO_PANIC;
+
+ return NBCON_PRIO_NORMAL;
+}
+
/**
* nbcon_alloc - Allocate and init the nbcon console specific data
* @con: Console to initialize
--
2.39.2
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