Merging debian version 6.9.7-1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 0 insertions, 472 deletions

diff --git a/debian/patches-rt/0033-printk-nbcon-Introduce-printing-kthreads.patch b/debian/patches-rt/0033-printk-nbcon-Introduce-printing-kthreads.patch
deleted file mode 100644
index 12f69b52fc..0000000000
--- a/debian/patches-rt/0033-printk-nbcon-Introduce-printing-kthreads.patch
+++ /dev/null
@@ -1,472 +0,0 @@
-From: Thomas Gleixner <tglx@linutronix.de>
-Date: Fri, 22 Sep 2023 14:12:21 +0000
-Subject: [PATCH 33/48] printk: nbcon: Introduce printing kthreads
-Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz
-
-Provide the main implementation for running a printer kthread
-per nbcon console that is takeover/handover aware.
-
-Co-developed-by: John Ogness <john.ogness@linutronix.de>
-Signed-off-by: John Ogness <john.ogness@linutronix.de>
-Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
-Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
----
- include/linux/console.h  |   26 ++++++
- kernel/printk/internal.h |   28 +++++++
- kernel/printk/nbcon.c    |  187 +++++++++++++++++++++++++++++++++++++++++++++--
- kernel/printk/printk.c   |   33 ++++++++
- 4 files changed, 269 insertions(+), 5 deletions(-)
-
---- a/include/linux/console.h
-+++ b/include/linux/console.h
-@@ -17,6 +17,7 @@
- #include <linux/atomic.h>
- #include <linux/bits.h>
- #include <linux/rculist.h>
-+#include <linux/rcuwait.h>
- #include <linux/types.h>
- 
- struct vc_data;
-@@ -324,6 +325,8 @@ struct nbcon_drvdata {
-  * @nbcon_state:	State for nbcon consoles
-  * @nbcon_seq:		Sequence number of the next record for nbcon to print
-  * @pbufs:		Pointer to nbcon private buffer
-+ * @kthread:		Printer kthread for this console
-+ * @rcuwait:		RCU-safe wait object for @kthread waking
-  */
- struct console {
- 	char			name[16];
-@@ -372,6 +375,27 @@ struct console {
- 	void (*write_atomic)(struct console *con, struct nbcon_write_context *wctxt);
- 
- 	/**
-+	 * @write_thread:
-+	 *
-+	 * NBCON callback to write out text in task context. (Optional)
-+	 *
-+	 * This callback is called with the console already acquired. Any
-+	 * additional driver synchronization should have been performed by
-+	 * device_lock().
-+	 *
-+	 * This callback is always called from task context but with migration
-+	 * disabled.
-+	 *
-+	 * The same criteria for console ownership verification and unsafe
-+	 * sections applies as with write_atomic(). The difference between
-+	 * this callback and write_atomic() is that this callback is used
-+	 * during normal operation and is always called from task context.
-+	 * This provides drivers with a relatively relaxed locking context
-+	 * for synchronizing output to the hardware.
-+	 */
-+	void (*write_thread)(struct console *con, struct nbcon_write_context *wctxt);
-+
-+	/**
- 	 * @device_lock:
- 	 *
- 	 * NBCON callback to begin synchronization with driver code.
-@@ -431,6 +455,8 @@ struct console {
- 	struct nbcon_drvdata	*nbcon_drvdata;
- 
- 	struct printk_buffers	*pbufs;
-+	struct task_struct	*kthread;
-+	struct rcuwait		rcuwait;
- };
- 
- #ifdef CONFIG_LOCKDEP
---- a/kernel/printk/internal.h
-+++ b/kernel/printk/internal.h
-@@ -90,6 +90,7 @@ enum nbcon_prio nbcon_get_default_prio(v
- void nbcon_atomic_flush_pending(void);
- bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
- 				   int cookie);
-+void nbcon_kthread_create(struct console *con);
- 
- /*
-  * Check if the given console is currently capable and allowed to print
-@@ -108,6 +109,8 @@ static inline bool console_is_usable(str
- 	if (flags & CON_NBCON) {
- 		if (!con->write_atomic)
- 			return false;
-+		if (!con->write_thread)
-+			return false;
- 	} else {
- 		if (!con->write)
- 			return false;
-@@ -124,12 +127,35 @@ static inline bool console_is_usable(str
- 	return true;
- }
- 
-+/**
-+ * nbcon_kthread_wake - Wake up a printk thread
-+ * @con:        Console to operate on
-+ */
-+static inline void nbcon_kthread_wake(struct console *con)
-+{
-+	/*
-+	 * Guarantee any new records can be seen by tasks preparing to wait
-+	 * before this context checks if the rcuwait is empty.
-+	 *
-+	 * The full memory barrier in rcuwait_wake_up() pairs with the full
-+	 * memory barrier within set_current_state() of
-+	 * ___rcuwait_wait_event(), which is called after prepare_to_rcuwait()
-+	 * adds the waiter but before it has checked the wait condition.
-+	 *
-+	 * This pairs with nbcon_kthread_func:A.
-+	 */
-+	rcuwait_wake_up(&con->rcuwait); /* LMM(nbcon_kthread_wake:A) */
-+}
-+
- #else
- 
- #define PRINTK_PREFIX_MAX	0
- #define PRINTK_MESSAGE_MAX	0
- #define PRINTKRB_RECORD_MAX	0
- 
-+static inline void nbcon_kthread_wake(struct console *con) { }
-+static inline void nbcon_kthread_create(struct console *con) { }
-+
- /*
-  * In !PRINTK builds we still export console_sem
-  * semaphore and some of console functions (console_unlock()/etc.), so
-@@ -153,6 +179,8 @@ static inline bool console_is_usable(str
- 
- #endif /* CONFIG_PRINTK */
- 
-+extern bool have_boot_console;
-+
- extern struct printk_buffers printk_shared_pbufs;
- 
- /**
---- a/kernel/printk/nbcon.c
-+++ b/kernel/printk/nbcon.c
-@@ -10,6 +10,7 @@
- #include <linux/export.h>
- #include <linux/init.h>
- #include <linux/irqflags.h>
-+#include <linux/kthread.h>
- #include <linux/minmax.h>
- #include <linux/percpu.h>
- #include <linux/preempt.h>
-@@ -837,6 +838,7 @@ EXPORT_SYMBOL_GPL(nbcon_exit_unsafe);
- /**
-  * nbcon_emit_next_record - Emit a record in the acquired context
-  * @wctxt:	The write context that will be handed to the write function
-+ * @use_atomic:	True if the write_atomic callback is to be used
-  *
-  * Return:	True if this context still owns the console. False if
-  *		ownership was handed over or taken.
-@@ -850,7 +852,7 @@ EXPORT_SYMBOL_GPL(nbcon_exit_unsafe);
-  * When true is returned, @wctxt->ctxt.backlog indicates whether there are
-  * still records pending in the ringbuffer,
-  */
--static bool nbcon_emit_next_record(struct nbcon_write_context *wctxt)
-+static bool nbcon_emit_next_record(struct nbcon_write_context *wctxt, bool use_atomic)
- {
- 	struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt);
- 	struct console *con = ctxt->console;
-@@ -899,8 +901,14 @@ static bool nbcon_emit_next_record(struc
- 	nbcon_state_read(con, &cur);
- 	wctxt->unsafe_takeover = cur.unsafe_takeover;
- 
--	if (con->write_atomic) {
-+	if (use_atomic &&
-+	    con->write_atomic) {
- 		con->write_atomic(con, wctxt);
-+
-+	} else if (!use_atomic &&
-+		   con->write_thread) {
-+		con->write_thread(con, wctxt);
-+
- 	} else {
- 		/*
- 		 * This function should never be called for legacy consoles.
-@@ -936,6 +944,118 @@ static bool nbcon_emit_next_record(struc
- 	return nbcon_context_exit_unsafe(ctxt);
- }
- 
-+/**
-+ * nbcon_kthread_should_wakeup - Check whether a printer thread should wakeup
-+ * @con:	Console to operate on
-+ * @ctxt:	The acquire context that contains the state
-+ *		at console_acquire()
-+ *
-+ * Return:	True if the thread should shutdown or if the console is
-+ *		allowed to print and a record is available. False otherwise.
-+ *
-+ * After the thread wakes up, it must first check if it should shutdown before
-+ * attempting any printing.
-+ */
-+static bool nbcon_kthread_should_wakeup(struct console *con, struct nbcon_context *ctxt)
-+{
-+	bool ret = false;
-+	short flags;
-+	int cookie;
-+
-+	if (kthread_should_stop())
-+		return true;
-+
-+	cookie = console_srcu_read_lock();
-+
-+	flags = console_srcu_read_flags(con);
-+	if (console_is_usable(con, flags)) {
-+		/* Bring the sequence in @ctxt up to date */
-+		ctxt->seq = nbcon_seq_read(con);
-+
-+		ret = prb_read_valid(prb, ctxt->seq, NULL);
-+	}
-+
-+	console_srcu_read_unlock(cookie);
-+	return ret;
-+}
-+
-+/**
-+ * nbcon_kthread_func - The printer thread function
-+ * @__console:	Console to operate on
-+ */
-+static int nbcon_kthread_func(void *__console)
-+{
-+	struct console *con = __console;
-+	struct nbcon_write_context wctxt = {
-+		.ctxt.console	= con,
-+		.ctxt.prio	= NBCON_PRIO_NORMAL,
-+	};
-+	struct nbcon_context *ctxt = &ACCESS_PRIVATE(&wctxt, ctxt);
-+	unsigned long flags;
-+	short con_flags;
-+	bool backlog;
-+	int cookie;
-+	int ret;
-+
-+wait_for_event:
-+	/*
-+	 * Guarantee this task is visible on the rcuwait before
-+	 * checking the wake condition.
-+	 *
-+	 * The full memory barrier within set_current_state() of
-+	 * ___rcuwait_wait_event() pairs with the full memory
-+	 * barrier within rcuwait_has_sleeper().
-+	 *
-+	 * This pairs with rcuwait_has_sleeper:A and nbcon_kthread_wake:A.
-+	 */
-+	ret = rcuwait_wait_event(&con->rcuwait,
-+				 nbcon_kthread_should_wakeup(con, ctxt),
-+				 TASK_INTERRUPTIBLE); /* LMM(nbcon_kthread_func:A) */
-+
-+	if (kthread_should_stop())
-+		return 0;
-+
-+	/* Wait was interrupted by a spurious signal, go back to sleep. */
-+	if (ret)
-+		goto wait_for_event;
-+
-+	do {
-+		backlog = false;
-+
-+		cookie = console_srcu_read_lock();
-+
-+		con_flags = console_srcu_read_flags(con);
-+
-+		if (console_is_usable(con, con_flags)) {
-+			con->device_lock(con, &flags);
-+
-+			/*
-+			 * Ensure this stays on the CPU to make handover and
-+			 * takeover possible.
-+			 */
-+			cant_migrate();
-+
-+			if (nbcon_context_try_acquire(ctxt)) {
-+				/*
-+				 * If the emit fails, this context is no
-+				 * longer the owner.
-+				 */
-+				if (nbcon_emit_next_record(&wctxt, false)) {
-+					nbcon_context_release(ctxt);
-+					backlog = ctxt->backlog;
-+				}
-+			}
-+
-+			con->device_unlock(con, flags);
-+		}
-+
-+		console_srcu_read_unlock(cookie);
-+
-+	} while (backlog);
-+
-+	goto wait_for_event;
-+}
-+
- /* Track the nbcon emergency nesting per CPU. */
- static DEFINE_PER_CPU(unsigned int, nbcon_pcpu_emergency_nesting);
- static unsigned int early_nbcon_pcpu_emergency_nesting __initdata;
-@@ -982,7 +1102,7 @@ static bool nbcon_atomic_emit_one(struct
- 	 * handed over or taken over. In both cases the context is no
- 	 * longer valid.
- 	 */
--	if (!nbcon_emit_next_record(wctxt))
-+	if (!nbcon_emit_next_record(wctxt, true))
- 		return true;
- 
- 	nbcon_context_release(ctxt);
-@@ -1091,7 +1211,7 @@ static bool __nbcon_atomic_flush_pending
- 		 * handed over or taken over. In both cases the context is no
- 		 * longer valid.
- 		 */
--		if (!nbcon_emit_next_record(&wctxt))
-+		if (!nbcon_emit_next_record(&wctxt, true))
- 			return true;
- 
- 		if (!ctxt->backlog)
-@@ -1230,6 +1350,63 @@ void nbcon_cpu_emergency_exit(void)
- }
- 
- /**
-+ * nbcon_kthread_stop - Stop a printer thread
-+ * @con:	Console to operate on
-+ */
-+static void nbcon_kthread_stop(struct console *con)
-+{
-+	lockdep_assert_console_list_lock_held();
-+
-+	if (!con->kthread)
-+		return;
-+
-+	kthread_stop(con->kthread);
-+	con->kthread = NULL;
-+}
-+
-+/**
-+ * nbcon_kthread_create - Create a printer thread
-+ * @con:	Console to operate on
-+ *
-+ * If it fails, let the console proceed. The atomic part might
-+ * be usable and useful.
-+ */
-+void nbcon_kthread_create(struct console *con)
-+{
-+	struct task_struct *kt;
-+
-+	lockdep_assert_console_list_lock_held();
-+
-+	if (!(con->flags & CON_NBCON) || !con->write_thread)
-+		return;
-+
-+	if (con->kthread)
-+		return;
-+
-+	/*
-+	 * Printer threads cannot be started as long as any boot console is
-+	 * registered because there is no way to synchronize the hardware
-+	 * registers between boot console code and regular console code.
-+	 */
-+	if (have_boot_console)
-+		return;
-+
-+	kt = kthread_run(nbcon_kthread_func, con, "pr/%s%d", con->name, con->index);
-+	if (IS_ERR(kt)) {
-+		con_printk(KERN_ERR, con, "failed to start printing thread\n");
-+		return;
-+	}
-+
-+	con->kthread = kt;
-+
-+	/*
-+	 * It is important that console printing threads are scheduled
-+	 * shortly after a printk call and with generous runtime budgets.
-+	 */
-+	sched_set_normal(con->kthread, -20);
-+}
-+
-+/**
-  * nbcon_alloc - Allocate buffers needed by the nbcon console
-  * @con:	Console to allocate buffers for
-  *
-@@ -1273,6 +1450,7 @@ void nbcon_init(struct console *con)
- 	/* nbcon_alloc() must have been called and successful! */
- 	BUG_ON(!con->pbufs);
- 
-+	rcuwait_init(&con->rcuwait);
- 	nbcon_seq_force(con, 0);
- 	nbcon_state_set(con, &state);
- }
-@@ -1285,6 +1463,7 @@ void nbcon_free(struct console *con)
- {
- 	struct nbcon_state state = { };
- 
-+	nbcon_kthread_stop(con);
- 	nbcon_state_set(con, &state);
- 
- 	/* Boot consoles share global printk buffers. */
---- a/kernel/printk/printk.c
-+++ b/kernel/printk/printk.c
-@@ -483,7 +483,7 @@ static bool have_nbcon_console;
-  * the console lock. This is because boot consoles and nbcon consoles may
-  * have mapped the same hardware.
-  */
--static bool have_boot_console;
-+bool have_boot_console;
- 
- /*
-  * Specifies if the console lock/unlock dance is needed for console
-@@ -2698,6 +2698,8 @@ void suspend_console(void)
- void resume_console(void)
- {
- 	struct console *con;
-+	short flags;
-+	int cookie;
- 
- 	if (!console_suspend_enabled)
- 		return;
-@@ -2714,6 +2716,14 @@ void resume_console(void)
- 	 */
- 	synchronize_srcu(&console_srcu);
- 
-+	cookie = console_srcu_read_lock();
-+	for_each_console_srcu(con) {
-+		flags = console_srcu_read_flags(con);
-+		if (flags & CON_NBCON)
-+			nbcon_kthread_wake(con);
-+	}
-+	console_srcu_read_unlock(cookie);
-+
- 	pr_flush(1000, true);
- }
- 
-@@ -3034,6 +3044,13 @@ static bool console_flush_all(bool do_co
- 			u64 printk_seq;
- 			bool progress;
- 
-+			/*
-+			 * console_flush_all() is only for legacy consoles,
-+			 * unless the nbcon console has no kthread printer.
-+			 */
-+			if ((flags & CON_NBCON) && con->kthread)
-+				continue;
-+
- 			if (!console_is_usable(con, flags))
- 				continue;
- 			any_usable = true;
-@@ -3327,9 +3344,23 @@ EXPORT_SYMBOL(console_stop);
- 
- void console_start(struct console *console)
- {
-+	short flags;
-+
- 	console_list_lock();
- 	console_srcu_write_flags(console, console->flags | CON_ENABLED);
-+	flags = console->flags;
- 	console_list_unlock();
-+
-+	/*
-+	 * Ensure that all SRCU list walks have completed. The related
-+	 * printing context must be able to see it is enabled so that
-+	 * it is guaranteed to wake up and resume printing.
-+	 */
-+	synchronize_srcu(&console_srcu);
-+
-+	if (flags & CON_NBCON)
-+		nbcon_kthread_wake(console);
-+
- 	__pr_flush(console, 1000, true);
- }
- EXPORT_SYMBOL(console_start);