diff options
Diffstat (limited to 'debian/patches-rt/0075-printk-Add-non-BKL-nbcon-console-basic-infrastructur.patch')
| -rw-r--r-- | debian/patches-rt/0075-printk-Add-non-BKL-nbcon-console-basic-infrastructur.patch | 261 |
1 files changed, 0 insertions, 261 deletions
diff --git a/debian/patches-rt/0075-printk-Add-non-BKL-nbcon-console-basic-infrastructur.patch b/debian/patches-rt/0075-printk-Add-non-BKL-nbcon-console-basic-infrastructur.patch deleted file mode 100644 index 00f7850c3..000000000 --- a/debian/patches-rt/0075-printk-Add-non-BKL-nbcon-console-basic-infrastructur.patch +++ /dev/null @@ -1,261 +0,0 @@ -From: Thomas Gleixner <tglx@linutronix.de> -Date: Sat, 16 Sep 2023 21:26:00 +0206 -Subject: [PATCH 075/134] printk: Add non-BKL (nbcon) console basic - infrastructure -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz - -The current console/printk subsystem is protected by a Big Kernel Lock, -(aka console_lock) which has ill defined semantics and is more or less -stateless. This puts severe limitations on the console subsystem and -makes forced takeover and output in emergency and panic situations a -fragile endeavour that is based on try and pray. - -The goal of non-BKL (nbcon) consoles is to break out of the console lock -jail and to provide a new infrastructure that avoids the pitfalls and -also allows console drivers to be gradually converted over. - -The proposed infrastructure aims for the following properties: - - - Per console locking instead of global locking - - Per console state that allows to make informed decisions - - Stateful handover and takeover - -As a first step, state is added to struct console. The per console state -is an atomic_t using a 32bit bit field. - -Reserve state bits, which will be populated later in the series. Wire -it up into the console register/unregister functionality. - -It was decided to use a bitfield because using a plain u32 with -mask/shift operations resulted in uncomprehensible code. - -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> -Reviewed-by: Petr Mladek <pmladek@suse.com> -Signed-off-by: Petr Mladek <pmladek@suse.com> -Link: https://lore.kernel.org/r/20230916192007.608398-2-john.ogness@linutronix.de -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - include/linux/console.h | 31 ++++++++++++++++++++ - kernel/printk/Makefile | 2 - - kernel/printk/internal.h | 8 +++++ - kernel/printk/nbcon.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++ - kernel/printk/printk.c | 13 ++++++-- - 5 files changed, 120 insertions(+), 4 deletions(-) - create mode 100644 kernel/printk/nbcon.c - ---- a/include/linux/console.h -+++ b/include/linux/console.h -@@ -156,6 +156,8 @@ static inline int con_debug_leave(void) - * /dev/kmesg which requires a larger output buffer. - * @CON_SUSPENDED: Indicates if a console is suspended. If true, the - * printing callbacks must not be called. -+ * @CON_NBCON: Console can operate outside of the legacy style console_lock -+ * constraints. - */ - enum cons_flags { - CON_PRINTBUFFER = BIT(0), -@@ -166,9 +168,33 @@ enum cons_flags { - CON_BRL = BIT(5), - CON_EXTENDED = BIT(6), - CON_SUSPENDED = BIT(7), -+ CON_NBCON = BIT(8), - }; - - /** -+ * struct nbcon_state - console state for nbcon consoles -+ * @atom: Compound of the state fields for atomic operations -+ * -+ * To be used for reading and preparing of the value stored in the nbcon -+ * state variable @console::nbcon_state. -+ */ -+struct nbcon_state { -+ union { -+ unsigned int atom; -+ struct { -+ }; -+ }; -+}; -+ -+/* -+ * The nbcon_state struct is used to easily create and interpret values that -+ * are stored in the @console::nbcon_state variable. Ensure this struct stays -+ * within the size boundaries of the atomic variable's underlying type in -+ * order to avoid any accidental truncation. -+ */ -+static_assert(sizeof(struct nbcon_state) <= sizeof(int)); -+ -+/** - * struct console - The console descriptor structure - * @name: The name of the console driver - * @write: Write callback to output messages (Optional) -@@ -187,6 +213,8 @@ enum cons_flags { - * @dropped: Number of unreported dropped ringbuffer records - * @data: Driver private data - * @node: hlist node for the console list -+ * -+ * @nbcon_state: State for nbcon consoles - */ - struct console { - char name[16]; -@@ -206,6 +234,9 @@ struct console { - unsigned long dropped; - void *data; - struct hlist_node node; -+ -+ /* nbcon console specific members */ -+ atomic_t __private nbcon_state; - }; - - #ifdef CONFIG_LOCKDEP ---- a/kernel/printk/Makefile -+++ b/kernel/printk/Makefile -@@ -1,6 +1,6 @@ - # SPDX-License-Identifier: GPL-2.0-only - obj-y = printk.o --obj-$(CONFIG_PRINTK) += printk_safe.o -+obj-$(CONFIG_PRINTK) += printk_safe.o nbcon.o - obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o - obj-$(CONFIG_PRINTK_INDEX) += index.o - ---- a/kernel/printk/internal.h -+++ b/kernel/printk/internal.h -@@ -3,6 +3,7 @@ - * internal.h - printk internal definitions - */ - #include <linux/percpu.h> -+#include <linux/console.h> - - #if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL) - void __init printk_sysctl_init(void); -@@ -61,6 +62,10 @@ void defer_console_output(void); - - u16 printk_parse_prefix(const char *text, int *level, - enum printk_info_flags *flags); -+ -+void nbcon_init(struct console *con); -+void nbcon_cleanup(struct console *con); -+ - #else - - #define PRINTK_PREFIX_MAX 0 -@@ -76,6 +81,9 @@ u16 printk_parse_prefix(const char *text - #define printk_safe_exit_irqrestore(flags) local_irq_restore(flags) - - static inline bool printk_percpu_data_ready(void) { return false; } -+static inline void nbcon_init(struct console *con) { } -+static inline void nbcon_cleanup(struct console *con) { } -+ - #endif /* CONFIG_PRINTK */ - - /** ---- /dev/null -+++ b/kernel/printk/nbcon.c -@@ -0,0 +1,70 @@ -+// SPDX-License-Identifier: GPL-2.0-only -+// Copyright (C) 2022 Linutronix GmbH, John Ogness -+// Copyright (C) 2022 Intel, Thomas Gleixner -+ -+#include <linux/kernel.h> -+#include <linux/console.h> -+#include "internal.h" -+/* -+ * Printk console printing implementation for consoles which does not depend -+ * on the legacy style console_lock mechanism. -+ */ -+ -+/** -+ * nbcon_state_set - Helper function to set the console state -+ * @con: Console to update -+ * @new: The new state to write -+ * -+ * Only to be used when the console is not yet or no longer visible in the -+ * system. Otherwise use nbcon_state_try_cmpxchg(). -+ */ -+static inline void nbcon_state_set(struct console *con, struct nbcon_state *new) -+{ -+ atomic_set(&ACCESS_PRIVATE(con, nbcon_state), new->atom); -+} -+ -+/** -+ * nbcon_state_read - Helper function to read the console state -+ * @con: Console to read -+ * @state: The state to store the result -+ */ -+static inline void nbcon_state_read(struct console *con, struct nbcon_state *state) -+{ -+ state->atom = atomic_read(&ACCESS_PRIVATE(con, nbcon_state)); -+} -+ -+/** -+ * nbcon_state_try_cmpxchg() - Helper function for atomic_try_cmpxchg() on console state -+ * @con: Console to update -+ * @cur: Old/expected state -+ * @new: New state -+ * -+ * Return: True on success. False on fail and @cur is updated. -+ */ -+static inline bool nbcon_state_try_cmpxchg(struct console *con, struct nbcon_state *cur, -+ struct nbcon_state *new) -+{ -+ return atomic_try_cmpxchg(&ACCESS_PRIVATE(con, nbcon_state), &cur->atom, new->atom); -+} -+ -+/** -+ * nbcon_init - Initialize the nbcon console specific data -+ * @con: Console to initialize -+ */ -+void nbcon_init(struct console *con) -+{ -+ struct nbcon_state state = { }; -+ -+ nbcon_state_set(con, &state); -+} -+ -+/** -+ * nbcon_cleanup - Cleanup the nbcon console specific data -+ * @con: Console to cleanup -+ */ -+void nbcon_cleanup(struct console *con) -+{ -+ struct nbcon_state state = { }; -+ -+ nbcon_state_set(con, &state); -+} ---- a/kernel/printk/printk.c -+++ b/kernel/printk/printk.c -@@ -3326,9 +3326,10 @@ static void try_enable_default_console(s - newcon->flags |= CON_CONSDEV; - } - --#define con_printk(lvl, con, fmt, ...) \ -- printk(lvl pr_fmt("%sconsole [%s%d] " fmt), \ -- (con->flags & CON_BOOT) ? "boot" : "", \ -+#define con_printk(lvl, con, fmt, ...) \ -+ printk(lvl pr_fmt("%s%sconsole [%s%d] " fmt), \ -+ (con->flags & CON_NBCON) ? "" : "legacy ", \ -+ (con->flags & CON_BOOT) ? "boot" : "", \ - con->name, con->index, ##__VA_ARGS__) - - static void console_init_seq(struct console *newcon, bool bootcon_registered) -@@ -3488,6 +3489,9 @@ void register_console(struct console *ne - newcon->dropped = 0; - console_init_seq(newcon, bootcon_registered); - -+ if (newcon->flags & CON_NBCON) -+ nbcon_init(newcon); -+ - /* - * Put this console in the list - keep the - * preferred driver at the head of the list. -@@ -3579,6 +3583,9 @@ static int unregister_console_locked(str - */ - synchronize_srcu(&console_srcu); - -+ if (console->flags & CON_NBCON) -+ nbcon_cleanup(console); -+ - console_sysfs_notify(); - - if (console->exit) |