Merge tag 'printk-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

 - Refactor printk code for formatting messages that are shown on
   consoles. This is a preparatory step for introducing atomic consoles
   which could not share the global buffers

 - Prevent memory leak when removing printk index in debugfs

 - Dump also the newest printk message by the sample gdbmacro

 - Fix a compiler warning

* tag 'printk-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printf: fix errname.c list
  kernel/printk/index.c: fix memory leak with using debugfs_lookup()
  printk: Use scnprintf() to print the message about the dropped messages on a console
  printk: adjust string limit macros
  printk: use printk_buffers for devkmsg
  printk: introduce console_prepend_dropped() for dropped messages
  printk: introduce printk_get_next_message() and printk_message
  printk: introduce struct printk_buffers
  console: Document struct console
  console: Use BIT() macros for @flags values
  printk: move size limit macros into internal.h
  docs: gdbmacros: print newest record

include/linux/console.h

@@ -15,6 +15,7 @@
 #define _LINUX_CONSOLE_H_ 1
 
 #include <linux/atomic.h>
+#include <linux/bits.h>
 #include <linux/rculist.h>
 #include <linux/types.h>
 
@@ -125,37 +126,82 @@ static inline int con_debug_leave(void)
 /*
  * The interface for a console, or any other device that wants to capture
  * console messages (printer driver?)
- *
- * If a console driver is marked CON_BOOT then it will be auto-unregistered
- * when the first real console is registered.  This is for early-printk drivers.
  */
 
-#define CON_PRINTBUFFER	(1)
-#define CON_CONSDEV	(2) /* Preferred console, /dev/console */
-#define CON_ENABLED	(4)
-#define CON_BOOT	(8)
-#define CON_ANYTIME	(16) /* Safe to call when cpu is offline */
-#define CON_BRL		(32) /* Used for a braille device */
-#define CON_EXTENDED	(64) /* Use the extended output format a la /dev/kmsg */
+/**
+ * cons_flags - General console flags
+ * @CON_PRINTBUFFER:	Used by newly registered consoles to avoid duplicate
+ *			output of messages that were already shown by boot
+ *			consoles or read by userspace via syslog() syscall.
+ * @CON_CONSDEV:	Indicates that the console driver is backing
+ *			/dev/console.
+ * @CON_ENABLED:	Indicates if a console is allowed to print records. If
+ *			false, the console also will not advance to later
+ *			records.
+ * @CON_BOOT:		Marks the console driver as early console driver which
+ *			is used during boot before the real driver becomes
+ *			available. It will be automatically unregistered
+ *			when the real console driver is registered unless
+ *			"keep_bootcon" parameter is used.
+ * @CON_ANYTIME:	A misnomed historical flag which tells the core code
+ *			that the legacy @console::write callback can be invoked
+ *			on a CPU which is marked OFFLINE. That is misleading as
+ *			it suggests that there is no contextual limit for
+ *			invoking the callback. The original motivation was
+ *			readiness of the per-CPU areas.
+ * @CON_BRL:		Indicates a braille device which is exempt from
+ *			receiving the printk spam for obvious reasons.
+ * @CON_EXTENDED:	The console supports the extended output format of
+ *			/dev/kmesg which requires a larger output buffer.
+ */
+enum cons_flags {
+	CON_PRINTBUFFER		= BIT(0),
+	CON_CONSDEV		= BIT(1),
+	CON_ENABLED		= BIT(2),
+	CON_BOOT		= BIT(3),
+	CON_ANYTIME		= BIT(4),
+	CON_BRL			= BIT(5),
+	CON_EXTENDED		= BIT(6),
+};
 
+/**
+ * struct console - The console descriptor structure
+ * @name:		The name of the console driver
+ * @write:		Write callback to output messages (Optional)
+ * @read:		Read callback for console input (Optional)
+ * @device:		The underlying TTY device driver (Optional)
+ * @unblank:		Callback to unblank the console (Optional)
+ * @setup:		Callback for initializing the console (Optional)
+ * @exit:		Callback for teardown of the console (Optional)
+ * @match:		Callback for matching a console (Optional)
+ * @flags:		Console flags. See enum cons_flags
+ * @index:		Console index, e.g. port number
+ * @cflag:		TTY control mode flags
+ * @ispeed:		TTY input speed
+ * @ospeed:		TTY output speed
+ * @seq:		Sequence number of the next ringbuffer record to print
+ * @dropped:		Number of unreported dropped ringbuffer records
+ * @data:		Driver private data
+ * @node:		hlist node for the console list
+ */
 struct console {
-	char	name[16];
-	void	(*write)(struct console *, const char *, unsigned);
-	int	(*read)(struct console *, char *, unsigned);
-	struct tty_driver *(*device)(struct console *, int *);
-	void	(*unblank)(void);
-	int	(*setup)(struct console *, char *);
-	int	(*exit)(struct console *);
-	int	(*match)(struct console *, char *name, int idx, char *options);
-	short	flags;
-	short	index;
-	int	cflag;
-	uint	ispeed;
-	uint	ospeed;
-	u64	seq;
-	unsigned long dropped;
-	void	*data;
-	struct hlist_node node;
+	char			name[16];
+	void			(*write)(struct console *co, const char *s, unsigned int count);
+	int			(*read)(struct console *co, char *s, unsigned int count);
+	struct tty_driver	*(*device)(struct console *co, int *index);
+	void			(*unblank)(void);
+	int			(*setup)(struct console *co, char *options);
+	int			(*exit)(struct console *co);
+	int			(*match)(struct console *co, char *name, int idx, char *options);
+	short			flags;
+	short			index;
+	int			cflag;
+	uint			ispeed;
+	uint			ospeed;
+	u64			seq;
+	unsigned long		dropped;
+	void			*data;
+	struct hlist_node	node;
 };
 
 #ifdef CONFIG_LOCKDEP

include/linux/printk.h

@@ -44,8 +44,6 @@ static inline const char *printk_skip_headers(const char *buffer)
 	return buffer;
 }
 
-#define CONSOLE_EXT_LOG_MAX	8192
-
 /* printk's without a loglevel use this.. */
 #define MESSAGE_LOGLEVEL_DEFAULT CONFIG_MESSAGE_LOGLEVEL_DEFAULT