1 files changed, 0 insertions, 478 deletions
diff --git a/debian/patches-rt/0014-printk-nbcon-Implement-processing-in-port-lock-wrapp.patch b/debian/patches-rt/0014-printk-nbcon-Implement-processing-in-port-lock-wrapp.patch
deleted file mode 100644
index edf62ea414..0000000000
--- a/debian/patches-rt/0014-printk-nbcon-Implement-processing-in-port-lock-wrapp.patch
+++ /dev/null
@@ -1,478 +0,0 @@
-From: John Ogness <john.ogness@linutronix.de>
-Date: Wed, 13 Sep 2023 08:35:23 +0000
-Subject: [PATCH 14/48] printk: nbcon: Implement processing in port->lock
- wrapper
-Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz
-
-Currently the port->lock wrappers uart_port_lock(),
-uart_port_unlock() (and their variants) only lock/unlock
-the spin_lock.
-
-If the port is an nbcon console, the wrappers must also
-acquire/release the console and mark the region as unsafe. This
-allows general port->lock synchronization to be synchronized
-with the nbcon console ownership.
-
-Introduce a new struct nbcon_drvdata within struct console that
-provides the necessary components for the port lock wrappers to
-acquire the nbcon console and track its ownership.
-
-Also introduce uart_port_set_cons() as a wrapper to set @cons
-of a uart_port. The wrapper sets @cons under the port lock in
-order to prevent @cons from disappearing while another context
-owns the port lock via the port lock wrappers.
-
-Also cleanup the description of the console_srcu_read_flags()
-function. It is used by the port lock wrappers to ensure a
-console cannot be fully unregistered while another context
-owns the port lock via the port lock wrappers.
-
-Signed-off-by: John Ogness <john.ogness@linutronix.de>
-Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
----
- drivers/tty/serial/8250/8250_core.c |    6 +-
- drivers/tty/serial/amba-pl011.c     |    2 
- drivers/tty/serial/serial_core.c    |   16 ++---
- include/linux/console.h             |   57 ++++++++++++++++----
- include/linux/printk.h              |   13 ++++
- include/linux/serial_core.h         |   98 +++++++++++++++++++++++++++++++++++-
- kernel/printk/nbcon.c               |   52 +++++++++++++++++++
- 7 files changed, 219 insertions(+), 25 deletions(-)
-
---- a/drivers/tty/serial/8250/8250_core.c
-+++ b/drivers/tty/serial/8250/8250_core.c
-@@ -627,11 +627,11 @@ static int univ8250_console_setup(struct
- 
- 	port = &serial8250_ports[co->index].port;
- 	/* link port to console */
--	port->cons = co;
-+	uart_port_set_cons(port, co);
- 
- 	retval = serial8250_console_setup(port, options, false);
- 	if (retval != 0)
--		port->cons = NULL;
-+		uart_port_set_cons(port, NULL);
- 	return retval;
- }
- 
-@@ -689,7 +689,7 @@ static int univ8250_console_match(struct
- 			continue;
- 
- 		co->index = i;
--		port->cons = co;
-+		uart_port_set_cons(port, co);
- 		return serial8250_console_setup(port, options, true);
- 	}
- 
---- a/drivers/tty/serial/amba-pl011.c
-+++ b/drivers/tty/serial/amba-pl011.c
-@@ -2488,7 +2488,7 @@ static int pl011_console_match(struct co
- 			continue;
- 
- 		co->index = i;
--		port->cons = co;
-+		uart_port_set_cons(port, co);
- 		return pl011_console_setup(co, options);
- 	}
- 
---- a/drivers/tty/serial/serial_core.c
-+++ b/drivers/tty/serial/serial_core.c
-@@ -3145,8 +3145,15 @@ static int serial_core_add_one_port(stru
- 	state->uart_port = uport;
- 	uport->state = state;
- 
-+	/*
-+	 * If this port is in use as a console then the spinlock is already
-+	 * initialised.
-+	 */
-+	if (!uart_console_registered(uport))
-+		uart_port_spin_lock_init(uport);
-+
- 	state->pm_state = UART_PM_STATE_UNDEFINED;
--	uport->cons = drv->cons;
-+	uart_port_set_cons(uport, drv->cons);
- 	uport->minor = drv->tty_driver->minor_start + uport->line;
- 	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
- 				drv->tty_driver->name_base + uport->line);
-@@ -3155,13 +3162,6 @@ static int serial_core_add_one_port(stru
- 		goto out;
- 	}
- 
--	/*
--	 * If this port is in use as a console then the spinlock is already
--	 * initialised.
--	 */
--	if (!uart_console_registered(uport))
--		uart_port_spin_lock_init(uport);
--
- 	if (uport->cons && uport->dev)
- 		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
- 
---- a/include/linux/console.h
-+++ b/include/linux/console.h
-@@ -283,6 +283,25 @@ struct nbcon_write_context {
- };
- 
- /**
-+ * struct nbcon_drvdata - Data to allow nbcon acquire in non-print context
-+ * @ctxt:		The core console context
-+ * @srcu_cookie:	Storage for a console_srcu_lock cookie, if needed
-+ * @owner_index:	Storage for the owning console index, if needed
-+ * @locked:		Storage for the locked state, if needed
-+ *
-+ * All fields (except for @ctxt) are available exclusively to the driver to
-+ * use as needed. They are not used by the printk subsystem.
-+ */
-+struct nbcon_drvdata {
-+	struct nbcon_context	__private ctxt;
-+
-+	/* reserved for driver use */
-+	int			srcu_cookie;
-+	short			owner_index;
-+	bool			locked;
-+};
-+
-+/**
-  * struct console - The console descriptor structure
-  * @name:		The name of the console driver
-  * @write:		Legacy write callback to output messages (Optional)
-@@ -396,6 +415,21 @@ struct console {
- 
- 	atomic_t		__private nbcon_state;
- 	atomic_long_t		__private nbcon_seq;
-+
-+	/**
-+	 * @nbcon_drvdata:
-+	 *
-+	 * Data for nbcon ownership tracking to allow acquiring nbcon consoles
-+	 * in non-printing contexts.
-+	 *
-+	 * Drivers may need to acquire nbcon consoles in non-printing
-+	 * contexts. This is achieved by providing a struct nbcon_drvdata.
-+	 * Then the driver can call nbcon_driver_acquire() and
-+	 * nbcon_driver_release(). The struct does not require any special
-+	 * initialization.
-+	 */
-+	struct nbcon_drvdata	*nbcon_drvdata;
-+
- 	struct printk_buffers	*pbufs;
- };
- 
-@@ -425,28 +459,29 @@ extern void console_list_unlock(void) __
- extern struct hlist_head console_list;
- 
- /**
-- * console_srcu_read_flags - Locklessly read the console flags
-+ * console_srcu_read_flags - Locklessly read flags of a possibly registered
-+ *				console
-  * @con:	struct console pointer of console to read flags from
-  *
-- * This function provides the necessary READ_ONCE() and data_race()
-- * notation for locklessly reading the console flags. The READ_ONCE()
-- * in this function matches the WRITE_ONCE() when @flags are modified
-- * for registered consoles with console_srcu_write_flags().
-+ * Locklessly reading @con->flags provides a consistent read value because
-+ * there is at most one CPU modifying @con->flags and that CPU is using only
-+ * read-modify-write operations to do so.
-  *
-- * Only use this function to read console flags when locklessly
-- * iterating the console list via srcu.
-+ * Requires console_srcu_read_lock to be held, which implies that @con might
-+ * be a registered console. If the caller is holding the console_list_lock or
-+ * it is certain that the console is not registered, the caller may read
-+ * @con->flags directly instead.
-  *
-  * Context: Any context.
-+ * Return: The current value of the @con->flags field.
-  */
- static inline short console_srcu_read_flags(const struct console *con)
- {
- 	WARN_ON_ONCE(!console_srcu_read_lock_is_held());
- 
- 	/*
--	 * Locklessly reading console->flags provides a consistent
--	 * read value because there is at most one CPU modifying
--	 * console->flags and that CPU is using only read-modify-write
--	 * operations to do so.
-+	 * The READ_ONCE() matches the WRITE_ONCE() when @flags are modified
-+	 * for registered consoles with console_srcu_write_flags().
- 	 */
- 	return data_race(READ_ONCE(con->flags));
- }
---- a/include/linux/printk.h
-+++ b/include/linux/printk.h
-@@ -9,6 +9,8 @@
- #include <linux/ratelimit_types.h>
- #include <linux/once_lite.h>
- 
-+struct console;
-+
- extern const char linux_banner[];
- extern const char linux_proc_banner[];
- 
-@@ -193,6 +195,8 @@ void show_regs_print_info(const char *lo
- extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold;
- extern asmlinkage void dump_stack(void) __cold;
- void printk_trigger_flush(void);
-+extern void nbcon_driver_acquire(struct console *con);
-+extern void nbcon_driver_release(struct console *con);
- #else
- static inline __printf(1, 0)
- int vprintk(const char *s, va_list args)
-@@ -272,6 +276,15 @@ static inline void dump_stack(void)
- static inline void printk_trigger_flush(void)
- {
- }
-+
-+static inline void nbcon_driver_acquire(struct console *con)
-+{
-+}
-+
-+static inline void nbcon_driver_release(struct console *con)
-+{
-+}
-+
- #endif
- 
- bool this_cpu_in_panic(void);
---- a/include/linux/serial_core.h
-+++ b/include/linux/serial_core.h
-@@ -8,10 +8,13 @@
- #define LINUX_SERIAL_CORE_H
- 
- #include <linux/bitops.h>
-+#include <linux/bug.h>
- #include <linux/compiler.h>
- #include <linux/console.h>
- #include <linux/interrupt.h>
- #include <linux/circ_buf.h>
-+#include <linux/lockdep.h>
-+#include <linux/printk.h>
- #include <linux/spinlock.h>
- #include <linux/sched.h>
- #include <linux/tty.h>
-@@ -607,12 +610,90 @@ static inline void __uart_port_unlock_ir
- }
- 
- /**
-+ * uart_port_set_cons - Safely set the @cons field for a uart
-+ * @up:		The uart port to set
-+ * @con:	The new console to set to
-+ *
-+ * This function must be used to set @up->cons. It uses the port lock to
-+ * synchronize with the port lock wrappers in order to ensure that the console
-+ * cannot change or disappear while another context is holding the port lock.
-+ */
-+static inline void uart_port_set_cons(struct uart_port *up, struct console *con)
-+{
-+	unsigned long flags;
-+
-+	__uart_port_lock_irqsave(up, &flags);
-+	up->cons = con;
-+	__uart_port_unlock_irqrestore(up, flags);
-+}
-+
-+/* Only for internal port lock wrapper usage. */
-+static inline void __uart_port_nbcon_acquire(struct uart_port *up)
-+{
-+	lockdep_assert_held_once(&up->lock);
-+
-+	if (likely(!uart_console(up)))
-+		return;
-+
-+	if (up->cons->nbcon_drvdata) {
-+		/*
-+		 * If @up->cons is registered, prevent it from fully
-+		 * unregistering until this context releases the nbcon.
-+		 */
-+		int cookie = console_srcu_read_lock();
-+
-+		/* Ensure console is registered and is an nbcon console. */
-+		if (!hlist_unhashed_lockless(&up->cons->node) &&
-+		    (console_srcu_read_flags(up->cons) & CON_NBCON)) {
-+			WARN_ON_ONCE(up->cons->nbcon_drvdata->locked);
-+
-+			nbcon_driver_acquire(up->cons);
-+
-+			/*
-+			 * Record @up->line to be used during release because
-+			 * @up->cons->index can change while the port and
-+			 * nbcon are locked.
-+			 */
-+			up->cons->nbcon_drvdata->owner_index = up->line;
-+			up->cons->nbcon_drvdata->srcu_cookie = cookie;
-+			up->cons->nbcon_drvdata->locked = true;
-+		} else {
-+			console_srcu_read_unlock(cookie);
-+		}
-+	}
-+}
-+
-+/* Only for internal port lock wrapper usage. */
-+static inline void __uart_port_nbcon_release(struct uart_port *up)
-+{
-+	lockdep_assert_held_once(&up->lock);
-+
-+	/*
-+	 * uart_console() cannot be used here because @up->cons->index might
-+	 * have changed. Check against @up->cons->nbcon_drvdata->owner_index
-+	 * instead.
-+	 */
-+
-+	if (unlikely(up->cons &&
-+		     up->cons->nbcon_drvdata &&
-+		     up->cons->nbcon_drvdata->locked &&
-+		     up->cons->nbcon_drvdata->owner_index == up->line)) {
-+		WARN_ON_ONCE(!up->cons->nbcon_drvdata->locked);
-+
-+		up->cons->nbcon_drvdata->locked = false;
-+		nbcon_driver_release(up->cons);
-+		console_srcu_read_unlock(up->cons->nbcon_drvdata->srcu_cookie);
-+	}
-+}
-+
-+/**
-  * uart_port_lock - Lock the UART port
-  * @up:		Pointer to UART port structure
-  */
- static inline void uart_port_lock(struct uart_port *up)
- {
- 	spin_lock(&up->lock);
-+	__uart_port_nbcon_acquire(up);
- }
- 
- /**
-@@ -622,6 +703,7 @@ static inline void uart_port_lock(struct
- static inline void uart_port_lock_irq(struct uart_port *up)
- {
- 	spin_lock_irq(&up->lock);
-+	__uart_port_nbcon_acquire(up);
- }
- 
- /**
-@@ -632,6 +714,7 @@ static inline void uart_port_lock_irq(st
- static inline void uart_port_lock_irqsave(struct uart_port *up, unsigned long *flags)
- {
- 	spin_lock_irqsave(&up->lock, *flags);
-+	__uart_port_nbcon_acquire(up);
- }
- 
- /**
-@@ -642,7 +725,11 @@ static inline void uart_port_lock_irqsav
-  */
- static inline bool uart_port_trylock(struct uart_port *up)
- {
--	return spin_trylock(&up->lock);
-+	if (!spin_trylock(&up->lock))
-+		return false;
-+
-+	__uart_port_nbcon_acquire(up);
-+	return true;
- }
- 
- /**
-@@ -654,7 +741,11 @@ static inline bool uart_port_trylock(str
-  */
- static inline bool uart_port_trylock_irqsave(struct uart_port *up, unsigned long *flags)
- {
--	return spin_trylock_irqsave(&up->lock, *flags);
-+	if (!spin_trylock_irqsave(&up->lock, *flags))
-+		return false;
-+
-+	__uart_port_nbcon_acquire(up);
-+	return true;
- }
- 
- /**
-@@ -663,6 +754,7 @@ static inline bool uart_port_trylock_irq
-  */
- static inline void uart_port_unlock(struct uart_port *up)
- {
-+	__uart_port_nbcon_release(up);
- 	spin_unlock(&up->lock);
- }
- 
-@@ -672,6 +764,7 @@ static inline void uart_port_unlock(stru
-  */
- static inline void uart_port_unlock_irq(struct uart_port *up)
- {
-+	__uart_port_nbcon_release(up);
- 	spin_unlock_irq(&up->lock);
- }
- 
-@@ -682,6 +775,7 @@ static inline void uart_port_unlock_irq(
-  */
- static inline void uart_port_unlock_irqrestore(struct uart_port *up, unsigned long flags)
- {
-+	__uart_port_nbcon_release(up);
- 	spin_unlock_irqrestore(&up->lock, flags);
- }
- 
---- a/kernel/printk/nbcon.c
-+++ b/kernel/printk/nbcon.c
-@@ -3,9 +3,12 @@
- // Copyright (C) 2022 Intel, Thomas Gleixner
- 
- #include <linux/kernel.h>
-+#include <linux/bug.h>
- #include <linux/console.h>
- #include <linux/delay.h>
-+#include <linux/export.h>
- #include <linux/slab.h>
-+#include <linux/string.h>
- #include "internal.h"
- /*
-  * Printk console printing implementation for consoles which does not depend
-@@ -988,3 +991,52 @@ void nbcon_free(struct console *con)
- 
- 	con->pbufs = NULL;
- }
-+
-+/**
-+ * nbcon_driver_acquire - Acquire nbcon console and enter unsafe section
-+ * @con:	The nbcon console to acquire
-+ *
-+ * Context:	Any context which could not be migrated to another CPU.
-+ *
-+ * Console drivers will usually use their own internal synchronization
-+ * mechasism to synchronize between console printing and non-printing
-+ * activities (such as setting baud rates). However, nbcon console drivers
-+ * supporting atomic consoles may also want to mark unsafe sections when
-+ * performing non-printing activities.
-+ *
-+ * This function acquires the nbcon console using priority NBCON_PRIO_NORMAL
-+ * and marks it unsafe for handover/takeover.
-+ *
-+ * Console drivers using this function must have provided @nbcon_drvdata in
-+ * their struct console, which is used to track ownership and state
-+ * information.
-+ */
-+void nbcon_driver_acquire(struct console *con)
-+{
-+	struct nbcon_context *ctxt = &ACCESS_PRIVATE(con->nbcon_drvdata, ctxt);
-+
-+	cant_migrate();
-+
-+	do {
-+		do {
-+			memset(ctxt, 0, sizeof(*ctxt));
-+			ctxt->console	= con;
-+			ctxt->prio	= NBCON_PRIO_NORMAL;
-+		} while (!nbcon_context_try_acquire(ctxt));
-+
-+	} while (!nbcon_context_enter_unsafe(ctxt));
-+}
-+EXPORT_SYMBOL_GPL(nbcon_driver_acquire);
-+
-+/**
-+ * nbcon_driver_release - Exit unsafe section and release the nbcon console
-+ * @con:	The nbcon console acquired in nbcon_driver_acquire()
-+ */
-+void nbcon_driver_release(struct console *con)
-+{
-+	struct nbcon_context *ctxt = &ACCESS_PRIVATE(con->nbcon_drvdata, ctxt);
-+
-+	if (nbcon_context_exit_unsafe(ctxt))
-+		nbcon_context_release(ctxt);
-+}
-+EXPORT_SYMBOL_GPL(nbcon_driver_release);