73 lines
2.6 KiB
Diff
73 lines
2.6 KiB
Diff
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From: John Ogness <john.ogness@linutronix.de>
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Date: Tue, 20 Aug 2024 08:35:45 +0206
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Subject: [PATCH 19/54] printk: nbcon: Add helper to assign priority based on
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CPU state
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.11/older/patches-6.11-rt7.tar.xz
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Add a helper function to use the current state of the CPU to
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determine which priority to assign to the printing context.
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The EMERGENCY priority handling is added in a follow-up commit.
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It will use a per-CPU variable.
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Note: nbcon_device_try_acquire(), which is used by console
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drivers to acquire the nbcon console for non-printing
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activities, is hard-coded to always use NORMAL priority.
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Reviewed-by: Petr Mladek <pmladek@suse.com>
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Link: https://lore.kernel.org/r/20240820063001.36405-20-john.ogness@linutronix.de
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Signed-off-by: Petr Mladek <pmladek@suse.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/printk/internal.h | 2 ++
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kernel/printk/nbcon.c | 19 +++++++++++++++++++
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2 files changed, 21 insertions(+)
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--- a/kernel/printk/internal.h
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+++ b/kernel/printk/internal.h
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@@ -83,6 +83,7 @@ u64 nbcon_seq_read(struct console *con);
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void nbcon_seq_force(struct console *con, u64 seq);
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bool nbcon_alloc(struct console *con);
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void nbcon_free(struct console *con);
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+enum nbcon_prio nbcon_get_default_prio(void);
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/*
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* Check if the given console is currently capable and allowed to print
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@@ -136,6 +137,7 @@ static inline u64 nbcon_seq_read(struct
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static inline void nbcon_seq_force(struct console *con, u64 seq) { }
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static inline bool nbcon_alloc(struct console *con) { return false; }
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static inline void nbcon_free(struct console *con) { }
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+static inline enum nbcon_prio nbcon_get_default_prio(void) { return NBCON_PRIO_NONE; }
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static inline bool console_is_usable(struct console *con, short flags) { return false; }
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -974,6 +974,25 @@ static bool nbcon_emit_next_record(struc
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}
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/**
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+ * nbcon_get_default_prio - The appropriate nbcon priority to use for nbcon
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+ * printing on the current CPU
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+ *
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+ * Context: Any context.
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+ * Return: The nbcon_prio to use for acquiring an nbcon console in this
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+ * context for printing.
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+ *
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+ * The function is safe for reading per-CPU data in any context because
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+ * preemption is disabled if the current CPU is in the panic state.
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+ */
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+enum nbcon_prio nbcon_get_default_prio(void)
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+{
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+ if (this_cpu_in_panic())
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+ return NBCON_PRIO_PANIC;
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+
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+ return NBCON_PRIO_NORMAL;
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+}
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+
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+/**
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* nbcon_alloc - Allocate and init the nbcon console specific data
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* @con: Console to initialize
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*
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