145 lines
4.3 KiB
Diff
145 lines
4.3 KiB
Diff
From 01b3747045371d9acb12427b75bc1d769c9c58c0 Mon Sep 17 00:00:00 2001
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From: John Ogness <john.ogness@linutronix.de>
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Date: Tue, 5 Dec 2023 14:09:31 +0000
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Subject: [PATCH 152/196] printk: nbcon: Start printing threads
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If there are no boot consoles, the printing threads are started
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in early_initcall.
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If there are boot consoles, the printing threads are started
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after the last boot console has unregistered. The printing
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threads do not need to be concerned about boot consoles because
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boot consoles cannot register once a non-boot console has
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registered.
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Until a printing thread of a console has started, that console
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will print using atomic_write() in the printk() caller context.
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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 | 18 +++++++++++++++++-
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kernel/printk/printk.c | 14 ++++++++++++++
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3 files changed, 33 insertions(+), 1 deletion(-)
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diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
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index 578623e7f0fc..dcf365635f71 100644
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--- a/kernel/printk/internal.h
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+++ b/kernel/printk/internal.h
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@@ -44,6 +44,7 @@ enum printk_info_flags {
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};
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extern struct printk_ringbuffer *prb;
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+extern bool printk_threads_enabled;
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extern bool have_legacy_console;
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extern bool have_boot_console;
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@@ -161,6 +162,7 @@ static inline void nbcon_kthread_wake(struct console *con)
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static inline void nbcon_kthread_wake(struct console *con) { }
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static inline void nbcon_kthread_create(struct console *con) { }
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+#define printk_threads_enabled (false)
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#define printing_via_unlock (false)
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/*
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diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
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index 57ed4968a653..b866d0138fe0 100644
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -205,6 +205,8 @@ static void nbcon_seq_try_update(struct nbcon_context *ctxt, u64 new_seq)
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}
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}
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+bool printk_threads_enabled __ro_after_init;
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+
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/**
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* nbcon_context_try_acquire_direct - Try to acquire directly
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* @ctxt: The context of the caller
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@@ -1401,7 +1403,7 @@ void nbcon_kthread_create(struct console *con)
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if (!(con->flags & CON_NBCON) || !con->write_thread)
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return;
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- if (con->kthread)
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+ if (!printk_threads_enabled || con->kthread)
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return;
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/*
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@@ -1427,6 +1429,19 @@ void nbcon_kthread_create(struct console *con)
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sched_set_normal(con->kthread, -20);
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}
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+static int __init printk_setup_threads(void)
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+{
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+ struct console *con;
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+
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+ console_list_lock();
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+ printk_threads_enabled = true;
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+ for_each_console(con)
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+ nbcon_kthread_create(con);
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+ console_list_unlock();
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+ return 0;
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+}
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+early_initcall(printk_setup_threads);
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+
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/**
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* nbcon_alloc - Allocate buffers needed by the nbcon console
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* @con: Console to allocate buffers for
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@@ -1477,6 +1492,7 @@ void nbcon_init(struct console *con)
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init_irq_work(&con->irq_work, nbcon_irq_work);
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nbcon_seq_force(con, con->seq);
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nbcon_state_set(con, &state);
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+ nbcon_kthread_create(con);
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}
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/**
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diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
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index 41370f284216..f45917a059db 100644
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--- a/kernel/printk/printk.c
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+++ b/kernel/printk/printk.c
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@@ -2389,6 +2389,9 @@ asmlinkage int vprintk_emit(int facility, int level,
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*
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* - When this CPU is in panic.
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*
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+ * - When booting, before the printing threads have been
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+ * started.
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+ *
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* - During shutdown, since the printing threads may not get
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* a chance to print the final messages.
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*
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@@ -2398,6 +2401,7 @@ asmlinkage int vprintk_emit(int facility, int level,
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* with boot consoles.
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*/
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if (is_panic_context ||
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+ !printk_threads_enabled ||
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(system_state > SYSTEM_RUNNING)) {
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nbcon_atomic_flush_all();
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}
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@@ -3685,6 +3689,7 @@ EXPORT_SYMBOL(register_console);
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/* Must be called under console_list_lock(). */
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static int unregister_console_locked(struct console *console)
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{
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+ bool is_boot_con = (console->flags & CON_BOOT);
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bool found_legacy_con = false;
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bool found_nbcon_con = false;
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bool found_boot_con = false;
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@@ -3756,6 +3761,15 @@ static int unregister_console_locked(struct console *console)
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if (!found_nbcon_con)
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have_nbcon_console = false;
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+ /*
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+ * When the last boot console unregisters, start up the
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+ * printing threads.
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+ */
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+ if (is_boot_con && !have_boot_console) {
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+ for_each_console(c)
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+ nbcon_kthread_create(c);
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+ }
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+
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return res;
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}
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--
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2.43.2
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