121 lines
4.2 KiB
Diff
121 lines
4.2 KiB
Diff
From a920606f828c8a5794abe28fad17f92d92857626 Mon Sep 17 00:00:00 2001
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From: John Ogness <john.ogness@linutronix.de>
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Date: Thu, 14 Dec 2023 14:38:42 +0000
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Subject: [PATCH 137/196] printk: nbcon: Assign priority based on CPU state
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Use the current state of the CPU to determine which priority to
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assign to the printing context.
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Note: The uart_port wrapper, which is responsible for non-console-
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printing activities, will always use NORMAL priority.
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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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 | 30 ++++++++++++++++++++++++++++--
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2 files changed, 30 insertions(+), 2 deletions(-)
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diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
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index e7cdea097cec..c4417fc48b7e 100644
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--- a/kernel/printk/internal.h
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+++ b/kernel/printk/internal.h
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@@ -79,6 +79,7 @@ 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_init(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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void nbcon_atomic_flush_all(void);
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bool nbcon_atomic_emit_next_record(struct console *con, bool *handover, int cookie);
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@@ -135,6 +136,7 @@ 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_init(struct console *con) { }
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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 void nbcon_atomic_flush_all(void) { }
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static inline bool nbcon_atomic_emit_next_record(struct console *con, bool *handover,
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int cookie) { return false; }
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diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
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index c17cf3ea6153..3e999784ba5c 100644
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -961,6 +961,22 @@ static bool nbcon_atomic_emit_one(struct nbcon_write_context *wctxt)
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return ctxt->backlog;
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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 which could not be migrated to another CPU.
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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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+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_atomic_emit_next_record - Print one record for an nbcon console
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* using the write_atomic() callback
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@@ -997,7 +1013,7 @@ bool nbcon_atomic_emit_next_record(struct console *con, bool *handover, int cook
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cant_migrate();
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ctxt->console = con;
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- ctxt->prio = NBCON_PRIO_NORMAL;
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+ ctxt->prio = nbcon_get_default_prio();
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progress = nbcon_atomic_emit_one(&wctxt);
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@@ -1043,7 +1059,6 @@ static void __nbcon_atomic_flush_all(u64 stop_seq)
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memset(ctxt, 0, sizeof(*ctxt));
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ctxt->console = con;
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ctxt->spinwait_max_us = 2000;
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- ctxt->prio = NBCON_PRIO_NORMAL;
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/*
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* Atomic flushing does not use console driver
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@@ -1052,9 +1067,14 @@ static void __nbcon_atomic_flush_all(u64 stop_seq)
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* disabled to avoid being interrupted and then
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* calling into a driver that will deadlock trying
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* acquire console ownership.
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+ *
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+ * This also disables migration in order to get the
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+ * current CPU priority.
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*/
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local_irq_save(irq_flags);
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+ ctxt->prio = nbcon_get_default_prio();
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+
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any_progress |= nbcon_atomic_emit_one(&wctxt);
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local_irq_restore(irq_flags);
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@@ -1166,6 +1186,9 @@ static inline bool uart_is_nbcon(struct uart_port *up)
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*
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* If @up is an nbcon console, this console will be acquired and marked as
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* unsafe. Otherwise this function does nothing.
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+ *
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+ * nbcon consoles acquired via the port lock wrapper always use priority
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+ * NBCON_PRIO_NORMAL.
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*/
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void nbcon_acquire(struct uart_port *up)
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{
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@@ -1200,6 +1223,9 @@ EXPORT_SYMBOL_GPL(nbcon_acquire);
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*
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* If @up is an nbcon console, the console will be marked as safe and
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* released. Otherwise this function does nothing.
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+ *
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+ * nbcon consoles acquired via the port lock wrapper always use priority
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+ * NBCON_PRIO_NORMAL.
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*/
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void nbcon_release(struct uart_port *up)
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{
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--
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2.43.2
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