Adding debian version 6.6.15-2.debian/6.6.15-2

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

1 files changed, 134 insertions, 0 deletions

diff --git a/debian/patches-rt/0115-printk-Coordinate-direct-printing-in-panic.patch b/debian/patches-rt/0115-printk-Coordinate-direct-printing-in-panic.patch
new file mode 100644
index 0000000000..972df76688
--- /dev/null
+++ b/debian/patches-rt/0115-printk-Coordinate-direct-printing-in-panic.patch
@@ -0,0 +1,134 @@
+From: John Ogness <john.ogness@linutronix.de>
+Date: Wed, 22 Nov 2023 11:56:58 +0000
+Subject: [PATCH 115/134] printk: Coordinate direct printing in panic
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
+
+Perform printing by nbcon consoles on the panic CPU from the
+printk() caller context in order to get panic messages printed
+as soon as possible.
+
+If legacy and nbcon consoles are registered, the legacy consoles
+will no longer perform direct printing on the panic CPU until
+after the backtrace has been stored. This will give the safe
+nbcon consoles a chance to print the panic messages before
+allowing the unsafe legacy consoles to print.
+
+If no nbcon consoles are registered, there is no change in
+behavior (i.e. legacy consoles will always attempt to print
+from the printk() caller context).
+
+Signed-off-by: John Ogness <john.ogness@linutronix.de>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ include/linux/printk.h |    2 +
+ kernel/panic.c         |    2 +
+ kernel/printk/printk.c |   53 ++++++++++++++++++++++++++++++++++++++++++-------
+ 3 files changed, 50 insertions(+), 7 deletions(-)
+
+--- a/include/linux/printk.h
++++ b/include/linux/printk.h
+@@ -782,3 +782,5 @@ static inline void print_hex_dump_debug(
+ 	print_hex_dump_debug(prefix_str, prefix_type, 16, 1, buf, len, true)
+ 
+ #endif
++
++void printk_legacy_allow_panic_sync(void);
+--- a/kernel/panic.c
++++ b/kernel/panic.c
+@@ -366,6 +366,8 @@ void panic(const char *fmt, ...)
+ 	 */
+ 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
+ 
++	printk_legacy_allow_panic_sync();
++
+ 	panic_print_sys_info(false);
+ 
+ 	kmsg_dump(KMSG_DUMP_PANIC);
+--- a/kernel/printk/printk.c
++++ b/kernel/printk/printk.c
+@@ -2330,12 +2330,23 @@ int vprintk_store(int facility, int leve
+ 	return ret;
+ }
+ 
++static bool legacy_allow_panic_sync;
++
++/*
++ * This acts as a one-way switch to allow legacy consoles to print from
++ * the printk() caller context on a panic CPU.
++ */
++void printk_legacy_allow_panic_sync(void)
++{
++	legacy_allow_panic_sync = true;
++}
++
+ asmlinkage int vprintk_emit(int facility, int level,
+ 			    const struct dev_printk_info *dev_info,
+ 			    const char *fmt, va_list args)
+ {
++	bool do_trylock_unlock = printing_via_unlock;
+ 	int printed_len;
+-	bool in_sched = false;
+ 
+ 	/* Suppress unimportant messages after panic happens */
+ 	if (unlikely(suppress_printk))
+@@ -2351,15 +2362,43 @@ asmlinkage int vprintk_emit(int facility
+ 
+ 	if (level == LOGLEVEL_SCHED) {
+ 		level = LOGLEVEL_DEFAULT;
+-		in_sched = true;
++		/* If called from the scheduler, we can not call up(). */
++		do_trylock_unlock = false;
+ 	}
+ 
+ 	printk_delay(level);
+ 
+ 	printed_len = vprintk_store(facility, level, dev_info, fmt, args);
+ 
+-	/* If called from the scheduler, we can not call up(). */
+-	if (!in_sched && printing_via_unlock) {
++	if (!have_boot_console && have_nbcon_console) {
++		bool is_panic_context = this_cpu_in_panic();
++
++		/*
++		 * In panic, the legacy consoles are not allowed to print from
++		 * the printk calling context unless explicitly allowed. This
++		 * gives the safe nbcon consoles a chance to print out all the
++		 * panic messages first. This restriction only applies if
++		 * there are nbcon consoles registered.
++		 */
++		if (is_panic_context)
++			do_trylock_unlock &= legacy_allow_panic_sync;
++
++		/*
++		 * There are situations where nbcon atomic printing should
++		 * happen in the printk() caller context:
++		 *
++		 * - When this CPU is in panic.
++		 *
++		 * Note that if boot consoles are registered, the
++		 * console_lock/console_unlock dance must be relied upon
++		 * instead because nbcon consoles cannot print simultaneously
++		 * with boot consoles.
++		 */
++		if (is_panic_context)
++			nbcon_atomic_flush_all();
++	}
++
++	if (do_trylock_unlock) {
+ 		/*
+ 		 * The caller may be holding system-critical or
+ 		 * timing-sensitive locks. Disable preemption during
+@@ -2379,10 +2418,10 @@ asmlinkage int vprintk_emit(int facility
+ 		preempt_enable();
+ 	}
+ 
+-	if (in_sched)
+-		defer_console_output();
+-	else
++	if (do_trylock_unlock)
+ 		wake_up_klogd();
++	else
++		defer_console_output();
+ 
+ 	return printed_len;
+ }