Printk changes for 5.9

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Merge tag 'printk-for-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

 - Herbert Xu made printk header file self-contained.

 - Andy Shevchenko and Sergey Senozhatsky cleaned up console->setup()
   error handling.

 - Andy Shevchenko did some cleanups (e.g. sparse warning) in vsprintf
   code.

 - Minor documentation updates.

* tag 'printk-for-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  lib/vsprintf: Force type of flags value for gfp_t
  lib/vsprintf: Replace custom spec to print decimals with generic one
  lib/vsprintf: Replace hidden BUILD_BUG_ON() with static_assert()
  printk: Make linux/printk.h self-contained
  doc:kmsg: explicitly state the return value in case of SEEK_CUR
  Replace HTTP links with HTTPS ones: vsprintf
  hvc: unify console setup naming
  console: Fix trivia typo 'change' -> 'chance'
  console: Propagate error code from console ->setup()
  tty: hvc: Return proper error code from console ->setup() hook
  serial: sunzilog: Return proper error code from console ->setup() hook
  serial: sunsab: Return proper error code from console ->setup() hook
  mips: Return proper error code from console ->setup() hook

Documentation/ABI/testing/dev-kmsg

@@ -56,6 +56,17 @@ Description:	The /dev/kmsg character device node provides userspace access
 		  seek after the last record available at the time
 		  the last SYSLOG_ACTION_CLEAR was issued.
 
+		Other seek operations or offsets are not supported because of
+		the special behavior this device has. The device allows to read
+		or write only whole variable length messages (records) that are
+		stored in a ring buffer.
+
+		Because of the non-standard behavior also the error values are
+		non-standard. -ESPIPE is returned for non-zero offset. -EINVAL
+		is returned for other operations, e.g. SEEK_CUR. This behavior
+		and values are historical and could not be modified without the
+		risk of breaking userspace.
+
 		The output format consists of a prefix carrying the syslog
 		prefix including priority and facility, the 64 bit message
 		sequence number and the monotonic timestamp in microseconds,

Documentation/core-api/printk-formats.rst

@@ -317,7 +317,7 @@ colon-separators. Leading zeros are always used.
 
 The additional ``c`` specifier can be used with the ``I`` specifier to
 print a compressed IPv6 address as described by
-http://tools.ietf.org/html/rfc5952
+https://tools.ietf.org/html/rfc5952
 
 Passed by reference.
 
@@ -341,7 +341,7 @@ The additional ``p``, ``f``, and ``s`` specifiers are used to specify port
 flowinfo a ``/`` and scope a ``%``, each followed by the actual value.
 
 In case of an IPv6 address the compressed IPv6 address as described by
-http://tools.ietf.org/html/rfc5952 is being used if the additional
+https://tools.ietf.org/html/rfc5952 is being used if the additional
 specifier ``c`` is given. The IPv6 address is surrounded by ``[``, ``]`` in
 case of additional specifiers ``p``, ``f`` or ``s`` as suggested by
 https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07

arch/mips/fw/arc/arc_con.c

@@ -28,7 +28,9 @@ static void prom_console_write(struct console *co, const char *s,
 
 static int prom_console_setup(struct console *co, char *options)
 {
-	return !(prom_flags & PROM_FLAG_USE_AS_CONSOLE);
+	if (prom_flags & PROM_FLAG_USE_AS_CONSOLE)
+		return 0;
+	return -ENODEV;
 }
 
 static struct console arc_cons = {

arch/s390/include/asm/bug.h

@@ -2,7 +2,7 @@
 #ifndef _ASM_S390_BUG_H
 #define _ASM_S390_BUG_H
 
-#include <linux/kernel.h>
+#include <linux/compiler.h>
 
 #ifdef CONFIG_BUG
 

drivers/tty/hvc/hvc_xen.c

@@ -603,7 +603,7 @@ static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
 #endif
 
 #ifdef CONFIG_EARLY_PRINTK
-static int __init xenboot_setup_console(struct console *console, char *string)
+static int __init xenboot_console_setup(struct console *console, char *string)
 {
 	static struct xencons_info xenboot;
 
@@ -647,7 +647,7 @@ static void xenboot_write_console(struct console *console, const char *string,
 struct console xenboot_console = {
 	.name		= "xenboot",
 	.write		= xenboot_write_console,
-	.setup		= xenboot_setup_console,
+	.setup		= xenboot_console_setup,
 	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 	.index		= -1,
 };

drivers/tty/hvc/hvsi.c

@@ -1128,7 +1128,7 @@ static int __init hvsi_console_setup(struct console *console, char *options)
 	int ret;
 
 	if (console->index < 0 || console->index >= hvsi_count)
-		return -1;
+		return -EINVAL;
 	hp = &hvsi_ports[console->index];
 
 	/* give the FSP a chance to change the baud rate when we re-open */

drivers/tty/serial/sunsab.c

@@ -886,7 +886,7 @@ static int sunsab_console_setup(struct console *con, char *options)
 	 * though...
 	 */
 	if (up->port.type != PORT_SUNSAB)
-		return -1;
+		return -EINVAL;
 
 	printk("Console: ttyS%d (SAB82532)\n",
 	       (sunsab_reg.minor - 64) + con->index);

drivers/tty/serial/sunzilog.c

@@ -1221,7 +1221,7 @@ static int __init sunzilog_console_setup(struct console *con, char *options)
 	int baud, brg;
 
 	if (up->port.type != PORT_SUNZILOG)
-		return -1;
+		return -EINVAL;
 
 	printk(KERN_INFO "Console: ttyS%d (SunZilog zs%d)\n",
 	       (sunzilog_reg.minor - 64) + con->index, con->index);

include/linux/printk.h

@@ -7,6 +7,7 @@
 #include <linux/kern_levels.h>
 #include <linux/linkage.h>
 #include <linux/cache.h>
+#include <linux/ratelimit_types.h>
 
 extern const char linux_banner[];
 extern const char linux_proc_banner[];

include/linux/ratelimit.h

@@ -2,41 +2,10 @@
 #ifndef _LINUX_RATELIMIT_H
 #define _LINUX_RATELIMIT_H
 
-#include <linux/param.h>
+#include <linux/ratelimit_types.h>
 #include <linux/sched.h>
 #include <linux/spinlock.h>
 
-#define DEFAULT_RATELIMIT_INTERVAL	(5 * HZ)
-#define DEFAULT_RATELIMIT_BURST		10
-
-/* issue num suppressed message on exit */
-#define RATELIMIT_MSG_ON_RELEASE	BIT(0)
-
-struct ratelimit_state {
-	raw_spinlock_t	lock;		/* protect the state */
-
-	int		interval;
-	int		burst;
-	int		printed;
-	int		missed;
-	unsigned long	begin;
-	unsigned long	flags;
-};
-
-#define RATELIMIT_STATE_INIT(name, interval_init, burst_init) {		\
-		.lock		= __RAW_SPIN_LOCK_UNLOCKED(name.lock),	\
-		.interval	= interval_init,			\
-		.burst		= burst_init,				\
-	}
-
-#define RATELIMIT_STATE_INIT_DISABLED					\
-	RATELIMIT_STATE_INIT(ratelimit_state, 0, DEFAULT_RATELIMIT_BURST)
-
-#define DEFINE_RATELIMIT_STATE(name, interval_init, burst_init)		\
-									\
-	struct ratelimit_state name =					\
-		RATELIMIT_STATE_INIT(name, interval_init, burst_init)	\
-
 static inline void ratelimit_state_init(struct ratelimit_state *rs,
 					int interval, int burst)
 {
@@ -73,9 +42,6 @@ ratelimit_set_flags(struct ratelimit_state *rs, unsigned long flags)
 
 extern struct ratelimit_state printk_ratelimit_state;
 
-extern int ___ratelimit(struct ratelimit_state *rs, const char *func);
-#define __ratelimit(state) ___ratelimit(state, __func__)
-
 #ifdef CONFIG_PRINTK
 
 #define WARN_ON_RATELIMIT(condition, state)	({		\

include/linux/ratelimit_types.h

@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_RATELIMIT_TYPES_H
+#define _LINUX_RATELIMIT_TYPES_H
+
+#include <linux/bits.h>
+#include <linux/param.h>
+#include <linux/spinlock_types.h>
+
+#define DEFAULT_RATELIMIT_INTERVAL	(5 * HZ)
+#define DEFAULT_RATELIMIT_BURST		10
+
+/* issue num suppressed message on exit */
+#define RATELIMIT_MSG_ON_RELEASE	BIT(0)
+
+struct ratelimit_state {
+	raw_spinlock_t	lock;		/* protect the state */
+
+	int		interval;
+	int		burst;
+	int		printed;
+	int		missed;
+	unsigned long	begin;
+	unsigned long	flags;
+};
+
+#define RATELIMIT_STATE_INIT(name, interval_init, burst_init) {		\
+		.lock		= __RAW_SPIN_LOCK_UNLOCKED(name.lock),	\
+		.interval	= interval_init,			\
+		.burst		= burst_init,				\
+	}
+
+#define RATELIMIT_STATE_INIT_DISABLED					\
+	RATELIMIT_STATE_INIT(ratelimit_state, 0, DEFAULT_RATELIMIT_BURST)
+
+#define DEFINE_RATELIMIT_STATE(name, interval_init, burst_init)		\
+									\
+	struct ratelimit_state name =					\
+		RATELIMIT_STATE_INIT(name, interval_init, burst_init)	\
+
+extern int ___ratelimit(struct ratelimit_state *rs, const char *func);
+#define __ratelimit(state) ___ratelimit(state, __func__)
+
+#endif /* _LINUX_RATELIMIT_TYPES_H */

kernel/printk/printk.c

@@ -943,6 +943,14 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
 	return ret;
 }
 
+/*
+ * Be careful when modifying this function!!!
+ *
+ * Only few operations are supported because the device works only with the
+ * entire variable length messages (records). Non-standard values are
+ * returned in the other cases and has been this way for quite some time.
+ * User space applications might depend on this behavior.
+ */
 static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct devkmsg_user *user = file->private_data;
@@ -2658,7 +2666,7 @@ early_param("keep_bootcon", keep_bootcon_setup);
 static int try_enable_new_console(struct console *newcon, bool user_specified)
 {
 	struct console_cmdline *c;
-	int i;
+	int i, err;
 
 	for (i = 0, c = console_cmdline;
 	     i < MAX_CMDLINECONSOLES && c->name[0];
@@ -2681,8 +2689,8 @@ static int try_enable_new_console(struct console *newcon, bool user_specified)
 				return 0;
 
 			if (newcon->setup &&
-			    newcon->setup(newcon, c->options) != 0)
+			    (err = newcon->setup(newcon, c->options)) != 0)
-				return -EIO;
+				return err;
 		}
 		newcon->flags |= CON_ENABLED;
 		if (i == preferred_console) {
@@ -2695,7 +2703,7 @@ static int try_enable_new_console(struct console *newcon, bool user_specified)
 	/*
 	 * Some consoles, such as pstore and netconsole, can be enabled even
 	 * without matching. Accept the pre-enabled consoles only when match()
-	 * and setup() had a change to be called.
+	 * and setup() had a chance to be called.
 	 */
 	if (newcon->flags & CON_ENABLED && c->user_specified ==	user_specified)
 		return 0;

lib/vsprintf.c

@@ -381,6 +381,9 @@ int num_to_str(char *buf, int size, unsigned long long num, unsigned int width)
 #define SMALL	32		/* use lowercase in hex (must be 32 == 0x20) */
 #define SPECIAL	64		/* prefix hex with "0x", octal with "0" */
 
+static_assert(ZEROPAD == ('0' - ' '));
+static_assert(SMALL == ' ');
+
 enum format_type {
 	FORMAT_TYPE_NONE, /* Just a string part */
 	FORMAT_TYPE_WIDTH,
@@ -507,7 +510,7 @@ char *number(char *buf, char *end, unsigned long long num,
 	/* zero or space padding */
 	if (!(spec.flags & LEFT)) {
 		char c = ' ' + (spec.flags & ZEROPAD);
-		BUILD_BUG_ON(' ' + ZEROPAD != '0');
+
 		while (--field_width >= 0) {
 			if (buf < end)
 				*buf = c;
@@ -1934,7 +1937,7 @@ char *flags_string(char *buf, char *end, void *flags_ptr,
 		names = vmaflag_names;
 		break;
 	case 'g':
-		flags = *(gfp_t *)flags_ptr;
+		flags = (__force unsigned long)(*(gfp_t *)flags_ptr);
 		names = gfpflag_names;
 		break;
 	default:
@@ -1976,12 +1979,6 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 	char *buf_start = buf;
 	struct property *prop;
 	bool has_mult, pass;
-	static const struct printf_spec num_spec = {
-		.flags = SMALL,
-		.field_width = -1,
-		.precision = -1,
-		.base = 10,
-	};
 
 	struct printf_spec str_spec = spec;
 	str_spec.field_width = -1;
@@ -2021,7 +2018,7 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 			str_spec.precision = precision;
 			break;
 		case 'p':	/* phandle */
-			buf = number(buf, end, (unsigned int)dn->phandle, num_spec);
+			buf = number(buf, end, (unsigned int)dn->phandle, default_dec_spec);
 			break;
 		case 'P':	/* path-spec */
 			p = fwnode_get_name(of_fwnode_handle(dn));
@@ -2134,7 +2131,7 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
  *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
  * - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order
  * - 'I[6S]c' for IPv6 addresses printed as specified by
- *       http://tools.ietf.org/html/rfc5952
+ *       https://tools.ietf.org/html/rfc5952
  * - 'E[achnops]' For an escaped buffer, where rules are defined by combination
  *                of the following flags (see string_escape_mem() for the
  *                details):