diff options
Diffstat (limited to 'debian/patches-rt/0038-printk-nbcon-Start-printing-threads.patch')
| -rw-r--r-- | debian/patches-rt/0038-printk-nbcon-Start-printing-threads.patch | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/debian/patches-rt/0038-printk-nbcon-Start-printing-threads.patch b/debian/patches-rt/0038-printk-nbcon-Start-printing-threads.patch new file mode 100644 index 000000000..63aae75eb --- /dev/null +++ b/debian/patches-rt/0038-printk-nbcon-Start-printing-threads.patch @@ -0,0 +1,135 @@ +From: John Ogness <john.ogness@linutronix.de> +Date: Tue, 5 Dec 2023 14:09:31 +0000 +Subject: [PATCH 38/48] printk: nbcon: Start printing threads +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz + +If there are no boot consoles, the printing threads are started +in early_initcall. + +If there are boot consoles, the printing threads are started +after the last boot console has unregistered. The printing +threads do not need to be concerned about boot consoles because +boot consoles cannot register once a non-boot console has +registered. + +Until a printing thread of a console has started, that console +will print using atomic_write() in the printk() caller context. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/printk/internal.h | 2 ++ + kernel/printk/nbcon.c | 18 +++++++++++++++++- + kernel/printk/printk.c | 14 ++++++++++++++ + 3 files changed, 33 insertions(+), 1 deletion(-) + +--- a/kernel/printk/internal.h ++++ b/kernel/printk/internal.h +@@ -48,6 +48,7 @@ struct printk_ringbuffer; + struct dev_printk_info; + + extern struct printk_ringbuffer *prb; ++extern bool printk_threads_enabled; + + __printf(4, 0) + int vprintk_store(int facility, int level, +@@ -159,6 +160,7 @@ static inline void nbcon_kthread_wake(st + + static inline void nbcon_kthread_wake(struct console *con) { } + static inline void nbcon_kthread_create(struct console *con) { } ++#define printk_threads_enabled (false) + + /* + * In !PRINTK builds we still export console_sem +--- a/kernel/printk/nbcon.c ++++ b/kernel/printk/nbcon.c +@@ -213,6 +213,8 @@ static void nbcon_seq_try_update(struct + } + } + ++bool printk_threads_enabled __ro_after_init; ++ + /** + * nbcon_context_try_acquire_direct - Try to acquire directly + * @ctxt: The context of the caller +@@ -1436,7 +1438,7 @@ void nbcon_kthread_create(struct console + if (!(con->flags & CON_NBCON) || !con->write_thread) + return; + +- if (con->kthread) ++ if (!printk_threads_enabled || con->kthread) + return; + + /* +@@ -1462,6 +1464,19 @@ void nbcon_kthread_create(struct console + sched_set_normal(con->kthread, -20); + } + ++static int __init printk_setup_threads(void) ++{ ++ struct console *con; ++ ++ console_list_lock(); ++ printk_threads_enabled = true; ++ for_each_console(con) ++ nbcon_kthread_create(con); ++ console_list_unlock(); ++ return 0; ++} ++early_initcall(printk_setup_threads); ++ + /** + * nbcon_alloc - Allocate buffers needed by the nbcon console + * @con: Console to allocate buffers for +@@ -1510,6 +1525,7 @@ void nbcon_init(struct console *con) + init_irq_work(&con->irq_work, nbcon_irq_work); + nbcon_seq_force(con, 0); + nbcon_state_set(con, &state); ++ nbcon_kthread_create(con); + } + + /** +--- a/kernel/printk/printk.c ++++ b/kernel/printk/printk.c +@@ -2402,6 +2402,9 @@ asmlinkage int vprintk_emit(int facility + * + * - When this CPU is in panic. + * ++ * - When booting, before the printing threads have been ++ * started. ++ * + * - During shutdown, since the printing threads may not get + * a chance to print the final messages. + * +@@ -2410,6 +2413,7 @@ asmlinkage int vprintk_emit(int facility + * consoles cannot print simultaneously with boot consoles. + */ + if (is_panic_context || ++ !printk_threads_enabled || + (system_state > SYSTEM_RUNNING)) { + nbcon_atomic_flush_pending(); + } +@@ -3726,6 +3730,7 @@ EXPORT_SYMBOL(register_console); + /* Must be called under console_list_lock(). */ + static int unregister_console_locked(struct console *console) + { ++ bool is_boot_con = (console->flags & CON_BOOT); + bool found_legacy_con = false; + bool found_nbcon_con = false; + bool found_boot_con = false; +@@ -3797,6 +3802,15 @@ static int unregister_console_locked(str + if (!found_nbcon_con) + have_nbcon_console = found_nbcon_con; + ++ /* ++ * When the last boot console unregisters, start up the ++ * printing threads. ++ */ ++ if (is_boot_con && !have_boot_console) { ++ for_each_console(c) ++ nbcon_kthread_create(c); ++ } ++ + return res; + } + |