Merging debian version 6.8.9-1.

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

1 files changed, 211 insertions, 67 deletions

diff --git a/debian/patches-rt/0048-printk-Add-kthread-for-all-legacy-consoles.patch b/debian/patches-rt/0046-printk-Add-kthread-for-all-legacy-consoles.patch
index 73a0c337be..e29281db8f 100644
--- a/debian/patches-rt/0048-printk-Add-kthread-for-all-legacy-consoles.patch
+++ b/debian/patches-rt/0046-printk-Add-kthread-for-all-legacy-consoles.patch
@@ -1,82 +1,210 @@
 From: John Ogness <john.ogness@linutronix.de>
 Date: Fri, 22 Sep 2023 17:35:04 +0000
-Subject: [PATCH 48/50] printk: Add kthread for all legacy consoles
-Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.7/older/patches-6.7-rt6.tar.xz
+Subject: [PATCH 46/48] printk: Add kthread for all legacy consoles
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz
 
-The write callback of legacy consoles make use of spinlocks.
+The write callback of legacy consoles makes use of spinlocks.
 This is not permitted with PREEMPT_RT in atomic contexts.
 
-Create a new kthread to handle printing of all the legacy
-consoles (and nbcon consoles if boot consoles are registered).
+For PREEMPT_RT, create a new kthread to handle printing of all
+the legacy consoles (and nbcon consoles if boot consoles are
+registered).
 
-Since the consoles are printing in a task context, it is no
-longer appropriate to support the legacy handover mechanism.
+Since, if running from the kthread, the consoles are printing
+in a task context, the legacy nbcon printing can use the
+device_lock(), write_thread(), device_unlock() callbacks for
+printing.
 
-These changes exist only for CONFIG_PREEMPT_RT.
+Introduce the macro force_printkthreads() to query if the
+forced threading of legacy consoles is in effect.
+
+These changes only affect CONFIG_PREEMPT_RT.
 
 Signed-off-by: John Ogness <john.ogness@linutronix.de>
 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 ---
- kernel/printk/internal.h |    1 
- kernel/printk/nbcon.c    |   18 ++-
- kernel/printk/printk.c   |  237 +++++++++++++++++++++++++++++++++++++++--------
- 3 files changed, 210 insertions(+), 46 deletions(-)
+ kernel/printk/internal.h |   20 +++
+ kernel/printk/nbcon.c    |   50 +++++----
+ kernel/printk/printk.c   |  252 +++++++++++++++++++++++++++++++++++++----------
+ 3 files changed, 251 insertions(+), 71 deletions(-)
 
 --- a/kernel/printk/internal.h
 +++ b/kernel/printk/internal.h
-@@ -95,6 +95,7 @@ void nbcon_atomic_flush_all(void);
- bool nbcon_atomic_emit_next_record(struct console *con, bool *handover, int cookie);
+@@ -21,6 +21,12 @@ int devkmsg_sysctl_set_loglvl(struct ctl
+ 		(con->flags & CON_BOOT) ? "boot" : "",		\
+ 		con->name, con->index, ##__VA_ARGS__)
+ 
++#ifdef CONFIG_PREEMPT_RT
++# define force_printkthreads()		(true)
++#else
++# define force_printkthreads()		(false)
++#endif
++
+ #ifdef CONFIG_PRINTK
+ 
+ #ifdef CONFIG_PRINTK_CALLER
+@@ -90,9 +96,10 @@ void nbcon_free(struct console *con);
+ enum nbcon_prio nbcon_get_default_prio(void);
+ void nbcon_atomic_flush_pending(void);
+ bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
+-				   int cookie);
++				   int cookie, bool use_atomic);
  void nbcon_kthread_create(struct console *con);
  void nbcon_wake_threads(void);
 +void nbcon_legacy_kthread_create(void);
  
  /*
   * Check if the given console is currently capable and allowed to print
+@@ -179,7 +186,7 @@ static inline void nbcon_free(struct con
+ static inline enum nbcon_prio nbcon_get_default_prio(void) { return NBCON_PRIO_NONE; }
+ static inline void nbcon_atomic_flush_pending(void) { }
+ static inline bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
+-						 int cookie) { return false; }
++						 int cookie, bool use_atomic) { return false; }
+ 
+ static inline bool console_is_usable(struct console *con, short flags,
+ 				     bool use_atomic) { return false; }
+@@ -187,6 +194,15 @@ static inline bool console_is_usable(str
+ #endif /* CONFIG_PRINTK */
+ 
+ extern bool have_boot_console;
++extern bool have_legacy_console;
++
++/*
++ * Specifies if the console lock/unlock dance is needed for console
++ * printing. If @have_boot_console is true, the nbcon consoles will
++ * be printed serially along with the legacy consoles because nbcon
++ * consoles cannot print simultaneously with boot consoles.
++ */
++#define printing_via_unlock (have_legacy_console || have_boot_console)
+ 
+ extern struct printk_buffers printk_shared_pbufs;
+ 
 --- a/kernel/printk/nbcon.c
 +++ b/kernel/printk/nbcon.c
-@@ -1247,9 +1247,11 @@ bool nbcon_atomic_emit_next_record(struc
+@@ -1202,9 +1202,10 @@ static __ref unsigned int *nbcon_get_cpu
+ }
+ 
+ /**
+- * nbcon_atomic_emit_one - Print one record for an nbcon console using the
+- *				write_atomic() callback
++ * nbcon_emit_one - Print one record for an nbcon console using the
++ *			specified callback
+  * @wctxt:	An initialized write context struct to use for this context
++ * @use_atomic:	True if the write_atomic callback is to be used
+  *
+  * Return:	False if it is known there are no more records to print,
+  *		otherwise true.
+@@ -1212,7 +1213,7 @@ static __ref unsigned int *nbcon_get_cpu
+  * This is an internal helper to handle the locking of the console before
+  * calling nbcon_emit_next_record().
+  */
+-static bool nbcon_atomic_emit_one(struct nbcon_write_context *wctxt)
++static bool nbcon_emit_one(struct nbcon_write_context *wctxt, bool use_atomic)
+ {
+ 	struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt);
+ 
+@@ -1224,7 +1225,7 @@ 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, true))
++	if (!nbcon_emit_next_record(wctxt, use_atomic))
+ 		return true;
+ 
+ 	nbcon_context_release(ctxt);
+@@ -1263,6 +1264,7 @@ enum nbcon_prio nbcon_get_default_prio(v
+  *		both the console_lock and the SRCU read lock. Otherwise it
+  *		is set to false.
+  * @cookie:	The cookie from the SRCU read lock.
++ * @use_atomic:	True if the write_atomic callback is to be used
+  *
+  * Context:	Any context except NMI.
+  * Return:	False if the given console has no next record to print,
+@@ -1273,7 +1275,7 @@ enum nbcon_prio nbcon_get_default_prio(v
+  * Essentially it is the nbcon version of console_emit_next_record().
+  */
+ bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
+-				   int cookie)
++				   int cookie, bool use_atomic)
+ {
+ 	struct nbcon_write_context wctxt = { };
+ 	struct nbcon_context *ctxt = &ACCESS_PRIVATE(&wctxt, ctxt);
+@@ -1282,19 +1284,29 @@ bool nbcon_legacy_emit_next_record(struc
+ 
  	*handover = false;
  
- 	/* Use the same locking order as console_emit_next_record(). */
+-	/* Use the same procedure as console_emit_next_record(). */
 -	printk_safe_enter_irqsave(flags);
 -	console_lock_spinning_enable();
 -	stop_critical_timings();
-+	if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
-+		printk_safe_enter_irqsave(flags);
-+		console_lock_spinning_enable();
-+		stop_critical_timings();
-+	}
- 
- 	con->driver_enter(con, &driver_flags);
- 	cant_migrate();
-@@ -1261,9 +1263,11 @@ bool nbcon_atomic_emit_next_record(struc
- 
- 	con->driver_exit(con, driver_flags);
- 
+-
+-	ctxt->console	= con;
+-	ctxt->prio	= nbcon_get_default_prio();
+-
+-	progress = nbcon_atomic_emit_one(&wctxt);
+-
 -	start_critical_timings();
 -	*handover = console_lock_spinning_disable_and_check(cookie);
 -	printk_safe_exit_irqrestore(flags);
-+	if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
++	ctxt->console = con;
++
++	if (use_atomic) {
++		/* Use the same procedure as console_emit_next_record(). */
++		printk_safe_enter_irqsave(flags);
++		console_lock_spinning_enable();
++		stop_critical_timings();
++
++		ctxt->prio = nbcon_get_default_prio();
++		progress = nbcon_emit_one(&wctxt, use_atomic);
++
 +		start_critical_timings();
 +		*handover = console_lock_spinning_disable_and_check(cookie);
 +		printk_safe_exit_irqrestore(flags);
++	} else {
++		con->device_lock(con, &flags);
++		cant_migrate();
++
++		ctxt->prio = nbcon_get_default_prio();
++		progress = nbcon_emit_one(&wctxt, use_atomic);
++
++		con->device_unlock(con, flags);
 +	}
  
  	return progress;
  }
-@@ -1469,6 +1473,8 @@ static int __init printk_setup_threads(v
+@@ -1536,6 +1548,8 @@ static int __init printk_setup_threads(v
  	printk_threads_enabled = true;
  	for_each_console(con)
  		nbcon_kthread_create(con);
-+	if (IS_ENABLED(CONFIG_PREEMPT_RT) && printing_via_unlock)
++	if (force_printkthreads() && printing_via_unlock)
 +		nbcon_legacy_kthread_create();
  	console_list_unlock();
  	return 0;
  }
 --- a/kernel/printk/printk.c
 +++ b/kernel/printk/printk.c
-@@ -487,6 +487,9 @@ bool have_boot_console;
+@@ -468,7 +468,7 @@ static DEFINE_MUTEX(syslog_lock);
+  * present, it is necessary to perform the console lock/unlock dance
+  * whenever console flushing should occur.
+  */
+-static bool have_legacy_console;
++bool have_legacy_console;
  
+ /*
+  * Specifies if an nbcon console is registered. If nbcon consoles are present,
+@@ -485,16 +485,11 @@ static bool have_nbcon_console;
+  */
+ bool have_boot_console;
+ 
+-/*
+- * Specifies if the console lock/unlock dance is needed for console
+- * printing. If @have_boot_console is true, the nbcon consoles will
+- * be printed serially along with the legacy consoles because nbcon
+- * consoles cannot print simultaneously with boot consoles.
+- */
+-#define printing_via_unlock (have_legacy_console || have_boot_console)
+-
  #ifdef CONFIG_PRINTK
  DECLARE_WAIT_QUEUE_HEAD(log_wait);
 +
@@ -85,17 +213,17 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  /* All 3 protected by @syslog_lock. */
  /* the next printk record to read by syslog(READ) or /proc/kmsg */
  static u64 syslog_seq;
-@@ -2344,7 +2347,8 @@ asmlinkage int vprintk_emit(int facility
+@@ -2358,7 +2353,8 @@ asmlinkage int vprintk_emit(int facility
  			    const struct dev_printk_info *dev_info,
  			    const char *fmt, va_list args)
  {
 -	bool do_trylock_unlock = printing_via_unlock;
 +	bool do_trylock_unlock = printing_via_unlock &&
-+				 !IS_ENABLED(CONFIG_PREEMPT_RT);
++				 !force_printkthreads();
  	int printed_len;
  
  	/* Suppress unimportant messages after panic happens */
-@@ -2472,6 +2476,14 @@ EXPORT_SYMBOL(_printk);
+@@ -2481,6 +2477,14 @@ EXPORT_SYMBOL(_printk);
  static bool pr_flush(int timeout_ms, bool reset_on_progress);
  static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress);
  
@@ -110,7 +238,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  #else /* CONFIG_PRINTK */
  
  #define printk_time		false
-@@ -2485,6 +2497,8 @@ static u64 syslog_seq;
+@@ -2494,6 +2498,8 @@ static u64 syslog_seq;
  static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; }
  static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; }
  
@@ -119,7 +247,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  #endif /* CONFIG_PRINTK */
  
  #ifdef CONFIG_EARLY_PRINTK
-@@ -2730,6 +2744,8 @@ void resume_console(void)
+@@ -2739,6 +2745,8 @@ void resume_console(void)
  	}
  	console_srcu_read_unlock(cookie);
  
@@ -128,17 +256,17 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  	pr_flush(1000, true);
  }
  
-@@ -2744,7 +2760,8 @@ void resume_console(void)
+@@ -2753,7 +2761,8 @@ void resume_console(void)
   */
  static int console_cpu_notify(unsigned int cpu)
  {
 -	if (!cpuhp_tasks_frozen && printing_via_unlock) {
 +	if (!cpuhp_tasks_frozen && printing_via_unlock &&
-+	    !IS_ENABLED(CONFIG_PREEMPT_RT)) {
++	    !force_printkthreads()) {
  		/* If trylock fails, someone else is doing the printing */
  		if (console_trylock())
  			console_unlock();
-@@ -2969,31 +2986,43 @@ static bool console_emit_next_record(str
+@@ -3013,31 +3022,43 @@ static bool console_emit_next_record(str
  		con->dropped = 0;
  	}
  
@@ -155,18 +283,16 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 -	printk_safe_enter_irqsave(flags);
 -	console_lock_spinning_enable();
 +	/* Write everything out to the hardware. */
- 
--	/* Do not trace print latency. */
--	stop_critical_timings();
-+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
++
++	if (force_printkthreads()) {
 +		/*
-+		 * On PREEMPT_RT this function is either in a thread or
-+		 * panic context. So there is no need for concern about
++		 * With forced threading this function is either in a thread
++		 * or panic context. So there is no need for concern about
 +		 * printk reentrance or handovers.
 +		 */
  
--	/* Write everything out to the hardware. */
--	con->write(con, outbuf, pmsg.outbuf_len);
+-	/* Do not trace print latency. */
+-	stop_critical_timings();
 +		con->write(con, outbuf, pmsg.outbuf_len);
 +		con->seq = pmsg.seq + 1;
 +	} else {
@@ -183,17 +309,19 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 +		printk_safe_enter_irqsave(flags);
 +		console_lock_spinning_enable();
  
--	start_critical_timings();
+-	/* Write everything out to the hardware. */
+-	con->write(con, outbuf, pmsg.outbuf_len);
 +		/* Do not trace print latency. */
 +		stop_critical_timings();
  
--	con->seq = pmsg.seq + 1;
+-	start_critical_timings();
 +		con->write(con, outbuf, pmsg.outbuf_len);
  
+-	con->seq = pmsg.seq + 1;
++		start_critical_timings();
+ 
 -	*handover = console_lock_spinning_disable_and_check(cookie);
 -	printk_safe_exit_irqrestore(flags);
-+		start_critical_timings();
-+
 +		con->seq = pmsg.seq + 1;
 +
 +		*handover = console_lock_spinning_disable_and_check(cookie);
@@ -202,7 +330,23 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  skip:
  	return true;
  }
-@@ -3103,19 +3132,7 @@ static bool console_flush_all(bool do_co
+@@ -3101,12 +3122,13 @@ static bool console_flush_all(bool do_co
+ 			if ((flags & CON_NBCON) && con->kthread)
+ 				continue;
+ 
+-			if (!console_is_usable(con, flags, true))
++			if (!console_is_usable(con, flags, !do_cond_resched))
+ 				continue;
+ 			any_usable = true;
+ 
+ 			if (flags & CON_NBCON) {
+-				progress = nbcon_legacy_emit_next_record(con, handover, cookie);
++				progress = nbcon_legacy_emit_next_record(con, handover, cookie,
++									 !do_cond_resched);
+ 				printk_seq = nbcon_seq_read(con);
+ 			} else {
+ 				progress = console_emit_next_record(con, handover, cookie);
+@@ -3145,19 +3167,7 @@ static bool console_flush_all(bool do_co
  	return false;
  }
  
@@ -223,7 +367,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  {
  	bool do_cond_resched;
  	bool handover;
-@@ -3159,6 +3176,32 @@ void console_unlock(void)
+@@ -3201,6 +3211,32 @@ void console_unlock(void)
  		 */
  	} while (prb_read_valid(prb, next_seq, NULL) && console_trylock());
  }
@@ -243,10 +387,10 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 +void console_unlock(void)
 +{
 +	/*
-+	 * PREEMPT_RT relies on kthread and atomic consoles for printing.
-+	 * It never attempts to print from console_unlock().
++	 * Forced threading relies on kthread and atomic consoles for
++	 * printing. It never attempts to print from console_unlock().
 +	 */
-+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
++	if (force_printkthreads()) {
 +		__console_unlock();
 +		return;
 +	}
@@ -256,7 +400,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  EXPORT_SYMBOL(console_unlock);
  
  /**
-@@ -3368,11 +3411,106 @@ void console_start(struct console *conso
+@@ -3410,11 +3446,106 @@ void console_start(struct console *conso
  
  	if (flags & CON_NBCON)
  		nbcon_kthread_wake(console);
@@ -338,7 +482,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 +
 +	lockdep_assert_held(&console_mutex);
 +
-+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
++	if (!force_printkthreads())
 +		return;
 +
 +	if (!printk_threads_enabled || nbcon_legacy_kthread)
@@ -363,15 +507,15 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  static int __read_mostly keep_bootcon;
  
  static int __init keep_bootcon_setup(char *str)
-@@ -3639,6 +3777,7 @@ void register_console(struct console *ne
- 		nbcon_init(newcon);
+@@ -3691,6 +3822,7 @@ void register_console(struct console *ne
+ 		newcon->seq = 0;
  	} else {
  		have_legacy_console = true;
 +		nbcon_legacy_kthread_create();
  	}
  
  	if (newcon->flags & CON_BOOT)
-@@ -3777,6 +3916,13 @@ static int unregister_console_locked(str
+@@ -3846,6 +3978,13 @@ static int unregister_console_locked(str
  			nbcon_kthread_create(c);
  	}
  
@@ -385,7 +529,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  	return res;
  }
  
-@@ -3936,8 +4082,12 @@ static bool __pr_flush(struct console *c
+@@ -4004,8 +4143,12 @@ static bool __pr_flush(struct console *c
  
  	seq = prb_next_reserve_seq(prb);
  
@@ -396,19 +540,19 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 +	 * Otherwise this function will just wait for the threaded printers
 +	 * to print up to @seq.
 +	 */
-+	if (printing_via_unlock && !IS_ENABLED(CONFIG_PREEMPT_RT)) {
++	if (printing_via_unlock && !force_printkthreads()) {
  		console_lock();
  		console_unlock();
  	}
-@@ -4045,9 +4195,16 @@ static void wake_up_klogd_work_func(stru
+@@ -4119,9 +4262,16 @@ static void wake_up_klogd_work_func(stru
  	int pending = this_cpu_xchg(printk_pending, 0);
  
  	if (pending & PRINTK_PENDING_OUTPUT) {
 -		/* If trylock fails, someone else is doing the printing */
 -		if (console_trylock())
 -			console_unlock();
-+		if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
-+			wake_up_interruptible(&legacy_wait);
++		if (force_printkthreads()) {
++			wake_up_legacy_kthread();
 +		} else {
 +			/*
 +			 * If trylock fails, some other context