1 files changed, 311 insertions, 168 deletions

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 7228258b85ec..de1a6bb6861d 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -45,6 +45,7 @@
 #include <linux/poll.h>
 #include <linux/irq_work.h>
 #include <linux/utsname.h>
+#include <linux/ctype.h>
 
 #include <asm/uaccess.h>
 
@@ -54,20 +55,16 @@
 #include "console_cmdline.h"
 #include "braille.h"
 
-/* printk's without a loglevel use this.. */
-#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
-
-/* We show everything that is MORE important than this.. */
-#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
-#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
-
 int console_printk[4] = {
-	DEFAULT_CONSOLE_LOGLEVEL,	/* console_loglevel */
-	DEFAULT_MESSAGE_LOGLEVEL,	/* default_message_loglevel */
-	MINIMUM_CONSOLE_LOGLEVEL,	/* minimum_console_loglevel */
-	DEFAULT_CONSOLE_LOGLEVEL,	/* default_console_loglevel */
+	CONSOLE_LOGLEVEL_DEFAULT,	/* console_loglevel */
+	MESSAGE_LOGLEVEL_DEFAULT,	/* default_message_loglevel */
+	CONSOLE_LOGLEVEL_MIN,		/* minimum_console_loglevel */
+	CONSOLE_LOGLEVEL_DEFAULT,	/* default_console_loglevel */
 };
 
+/* Deferred messaged from sched code are marked by this special level */
+#define SCHED_MESSAGE_LOGLEVEL -2
+
 /*
  * Low level drivers may need that to know if they can schedule in
  * their unblank() callback or not. So let's export it.
@@ -91,12 +88,35 @@ static struct lockdep_map console_lock_dep_map = {
 #endif
 
 /*
+ * Helper macros to handle lockdep when locking/unlocking console_sem. We use
+ * macros instead of functions so that _RET_IP_ contains useful information.
+ */
+#define down_console_sem() do { \
+	down(&console_sem);\
+	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
+} while (0)
+
+static int __down_trylock_console_sem(unsigned long ip)
+{
+	if (down_trylock(&console_sem))
+		return 1;
+	mutex_acquire(&console_lock_dep_map, 0, 1, ip);
+	return 0;
+}
+#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
+
+#define up_console_sem() do { \
+	mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
+	up(&console_sem);\
+} while (0)
+
+/*
  * This is used for debugging the mess that is the VT code by
  * keeping track if we have the console semaphore held. It's
  * definitely not the perfect debug tool (we don't know if _WE_
- * hold it are racing, but it helps tracking those weird code
- * path in the console code where we end up in places I want
- * locked without the console sempahore held
+ * hold it and are racing, but it helps tracking those weird code
+ * paths in the console code where we end up in places I want
+ * locked without the console sempahore held).
  */
 static int console_locked, console_suspended;
 
@@ -127,8 +147,8 @@ static int console_may_schedule;
  * the overall length of the record.
  *
  * The heads to the first and last entry in the buffer, as well as the
- * sequence numbers of these both entries are maintained when messages
- * are stored..
+ * sequence numbers of these entries are maintained when messages are
+ * stored.
  *
  * If the heads indicate available messages, the length in the header
  * tells the start next message. A length == 0 for the next message
@@ -206,8 +226,9 @@ struct printk_log {
 };
 
 /*
- * The logbuf_lock protects kmsg buffer, indices, counters. It is also
- * used in interesting ways to provide interlocking in console_unlock();
+ * The logbuf_lock protects kmsg buffer, indices, counters.  This can be taken
+ * within the scheduler's rq lock. It must be released before calling
+ * console_unlock() or anything else that might wake up a process.
  */
 static DEFINE_RAW_SPINLOCK(logbuf_lock);
 
@@ -237,7 +258,7 @@ static u64 clear_seq;
 static u32 clear_idx;
 
 #define PREFIX_MAX		32
-#define LOG_LINE_MAX		1024 - PREFIX_MAX
+#define LOG_LINE_MAX		(1024 - PREFIX_MAX)
 
 /* record buffer */
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
@@ -246,13 +267,11 @@ static u32 clear_idx;
 #define LOG_ALIGN __alignof__(struct printk_log)
 #endif
 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
+#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
 static char *log_buf = __log_buf;
 static u32 log_buf_len = __LOG_BUF_LEN;
 
-/* cpu currently holding logbuf_lock */
-static volatile unsigned int logbuf_cpu = UINT_MAX;
-
 /* human readable text of the record */
 static char *log_text(const struct printk_log *msg)
 {
@@ -297,34 +316,106 @@ static u32 log_next(u32 idx)
 	return idx + msg->len;
 }
 
-/* insert record into the buffer, discard old ones, update heads */
-static void log_store(int facility, int level,
-		      enum log_flags flags, u64 ts_nsec,
-		      const char *dict, u16 dict_len,
-		      const char *text, u16 text_len)
+/*
+ * Check whether there is enough free space for the given message.
+ *
+ * The same values of first_idx and next_idx mean that the buffer
+ * is either empty or full.
+ *
+ * If the buffer is empty, we must respect the position of the indexes.
+ * They cannot be reset to the beginning of the buffer.
+ */
+static int logbuf_has_space(u32 msg_size, bool empty)
 {
-	struct printk_log *msg;
-	u32 size, pad_len;
+	u32 free;
 
-	/* number of '\0' padding bytes to next message */
-	size = sizeof(struct printk_log) + text_len + dict_len;
-	pad_len = (-size) & (LOG_ALIGN - 1);
-	size += pad_len;
+	if (log_next_idx > log_first_idx || empty)
+		free = max(log_buf_len - log_next_idx, log_first_idx);
+	else
+		free = log_first_idx - log_next_idx;
+
+	/*
+	 * We need space also for an empty header that signalizes wrapping
+	 * of the buffer.
+	 */
+	return free >= msg_size + sizeof(struct printk_log);
+}
 
+static int log_make_free_space(u32 msg_size)
+{
 	while (log_first_seq < log_next_seq) {
-		u32 free;
+		if (logbuf_has_space(msg_size, false))
+			return 0;
+		/* drop old messages until we have enough contiguous space */
+		log_first_idx = log_next(log_first_idx);
+		log_first_seq++;
+	}
 
-		if (log_next_idx > log_first_idx)
-			free = max(log_buf_len - log_next_idx, log_first_idx);
-		else
-			free = log_first_idx - log_next_idx;
+	/* sequence numbers are equal, so the log buffer is empty */
+	if (logbuf_has_space(msg_size, true))
+		return 0;
 
-		if (free >= size + sizeof(struct printk_log))
-			break;
+	return -ENOMEM;
+}
 
-		/* drop old messages until we have enough contiuous space */
-		log_first_idx = log_next(log_first_idx);
-		log_first_seq++;
+/* compute the message size including the padding bytes */
+static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
+{
+	u32 size;
+
+	size = sizeof(struct printk_log) + text_len + dict_len;
+	*pad_len = (-size) & (LOG_ALIGN - 1);
+	size += *pad_len;
+
+	return size;
+}
+
+/*
+ * Define how much of the log buffer we could take at maximum. The value
+ * must be greater than two. Note that only half of the buffer is available
+ * when the index points to the middle.
+ */
+#define MAX_LOG_TAKE_PART 4
+static const char trunc_msg[] = "<truncated>";
+
+static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
+			u16 *dict_len, u32 *pad_len)
+{
+	/*
+	 * The message should not take the whole buffer. Otherwise, it might
+	 * get removed too soon.
+	 */
+	u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART;
+	if (*text_len > max_text_len)
+		*text_len = max_text_len;
+	/* enable the warning message */
+	*trunc_msg_len = strlen(trunc_msg);
+	/* disable the "dict" completely */
+	*dict_len = 0;
+	/* compute the size again, count also the warning message */
+	return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
+}
+
+/* insert record into the buffer, discard old ones, update heads */
+static int log_store(int facility, int level,
+		     enum log_flags flags, u64 ts_nsec,
+		     const char *dict, u16 dict_len,
+		     const char *text, u16 text_len)
+{
+	struct printk_log *msg;
+	u32 size, pad_len;
+	u16 trunc_msg_len = 0;
+
+	/* number of '\0' padding bytes to next message */
+	size = msg_used_size(text_len, dict_len, &pad_len);
+
+	if (log_make_free_space(size)) {
+		/* truncate the message if it is too long for empty buffer */
+		size = truncate_msg(&text_len, &trunc_msg_len,
+				    &dict_len, &pad_len);
+		/* survive when the log buffer is too small for trunc_msg */
+		if (log_make_free_space(size))
+			return 0;
 	}
 
 	if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
@@ -341,6 +432,10 @@ static void log_store(int facility, int level,
 	msg = (struct printk_log *)(log_buf + log_next_idx);
 	memcpy(log_text(msg), text, text_len);
 	msg->text_len = text_len;
+	if (trunc_msg_len) {
+		memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
+		msg->text_len += trunc_msg_len;
+	}
 	memcpy(log_dict(msg), dict, dict_len);
 	msg->dict_len = dict_len;
 	msg->facility = facility;
@@ -356,13 +451,11 @@ static void log_store(int facility, int level,
 	/* insert message */
 	log_next_idx += msg->len;
 	log_next_seq++;
+
+	return msg->text_len;
 }
 
-#ifdef CONFIG_SECURITY_DMESG_RESTRICT
-int dmesg_restrict = 1;
-#else
-int dmesg_restrict;
-#endif
+int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
 
 static int syslog_action_restricted(int type)
 {
@@ -733,34 +826,74 @@ void log_buf_kexec_setup(void)
 /* requested log_buf_len from kernel cmdline */
 static unsigned long __initdata new_log_buf_len;
 
-/* save requested log_buf_len since it's too early to process it */
-static int __init log_buf_len_setup(char *str)
+/* we practice scaling the ring buffer by powers of 2 */
+static void __init log_buf_len_update(unsigned size)
 {
-	unsigned size = memparse(str, &str);
-
 	if (size)
 		size = roundup_pow_of_two(size);
 	if (size > log_buf_len)
 		new_log_buf_len = size;
+}
+
+/* save requested log_buf_len since it's too early to process it */
+static int __init log_buf_len_setup(char *str)
+{
+	unsigned size = memparse(str, &str);
+
+	log_buf_len_update(size);
 
 	return 0;
 }
 early_param("log_buf_len", log_buf_len_setup);
 
+static void __init log_buf_add_cpu(void)
+{
+	unsigned int cpu_extra;
+
+	/*
+	 * archs should set up cpu_possible_bits properly with
+	 * set_cpu_possible() after setup_arch() but just in
+	 * case lets ensure this is valid.
+	 */
+	if (num_possible_cpus() == 1)
+		return;
+
+	cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
+
+	/* by default this will only continue through for large > 64 CPUs */
+	if (cpu_extra <= __LOG_BUF_LEN / 2)
+		return;
+
+	pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
+		__LOG_CPU_MAX_BUF_LEN);
+	pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
+		cpu_extra);
+	pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN);
+
+	log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
+}
+
 void __init setup_log_buf(int early)
 {
 	unsigned long flags;
 	char *new_log_buf;
 	int free;
 
+	if (log_buf != __log_buf)
+		return;
+
+	if (!early && !new_log_buf_len)
+		log_buf_add_cpu();
+
 	if (!new_log_buf_len)
 		return;
 
 	if (early) {
 		new_log_buf =
-			memblock_virt_alloc(new_log_buf_len, PAGE_SIZE);
+			memblock_virt_alloc(new_log_buf_len, LOG_ALIGN);
 	} else {
-		new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, 0);
+		new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len,
+							  LOG_ALIGN);
 	}
 
 	if (unlikely(!new_log_buf)) {
@@ -777,7 +910,7 @@ void __init setup_log_buf(int early)
 	memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
 	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
 
-	pr_info("log_buf_len: %d\n", log_buf_len);
+	pr_info("log_buf_len: %d bytes\n", log_buf_len);
 	pr_info("early log buf free: %d(%d%%)\n",
 		free, (free * 100) / __LOG_BUF_LEN);
 }
@@ -786,7 +919,7 @@ static bool __read_mostly ignore_loglevel;
 
 static int __init ignore_loglevel_setup(char *str)
 {
-	ignore_loglevel = 1;
+	ignore_loglevel = true;
 	pr_info("debug: ignoring loglevel setting.\n");
 
 	return 0;
@@ -852,11 +985,7 @@ static inline void boot_delay_msec(int level)
 }
 #endif
 
-#if defined(CONFIG_PRINTK_TIME)
-static bool printk_time = 1;
-#else
-static bool printk_time;
-#endif
+static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
 
 static size_t print_time(u64 ts, char *buf)
@@ -1215,7 +1344,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
 			 * for pending data, not the size; return the count of
 			 * records, not the length.
 			 */
-			error = log_next_idx - syslog_idx;
+			error = log_next_seq - syslog_seq;
 		} else {
 			u64 seq = syslog_seq;
 			u32 idx = syslog_idx;
@@ -1303,7 +1432,10 @@ static void zap_locks(void)
 	sema_init(&console_sem, 1);
 }
 
-/* Check if we have any console registered that can be called early in boot. */
+/*
+ * Check if we have any console that is capable of printing while cpu is
+ * booting or shutting down. Requires console_sem.
+ */
 static int have_callable_console(void)
 {
 	struct console *con;
@@ -1318,10 +1450,9 @@ static int have_callable_console(void)
 /*
  * Can we actually use the console at this time on this cpu?
  *
- * Console drivers may assume that per-cpu resources have
- * been allocated. So unless they're explicitly marked as
- * being able to cope (CON_ANYTIME) don't call them until
- * this CPU is officially up.
+ * Console drivers may assume that per-cpu resources have been allocated. So
+ * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
+ * call them until this CPU is officially up.
  */
 static inline int can_use_console(unsigned int cpu)
 {
@@ -1333,36 +1464,24 @@ static inline int can_use_console(unsigned int cpu)
  * messages from a 'printk'. Return true (and with the
  * console_lock held, and 'console_locked' set) if it
  * is successful, false otherwise.
- *
- * This gets called with the 'logbuf_lock' spinlock held and
- * interrupts disabled. It should return with 'lockbuf_lock'
- * released but interrupts still disabled.
  */
-static int console_trylock_for_printk(unsigned int cpu)
-	__releases(&logbuf_lock)
+static int console_trylock_for_printk(void)
 {
-	int retval = 0, wake = 0;
+	unsigned int cpu = smp_processor_id();
 
-	if (console_trylock()) {
-		retval = 1;
-
-		/*
-		 * If we can't use the console, we need to release
-		 * the console semaphore by hand to avoid flushing
-		 * the buffer. We need to hold the console semaphore
-		 * in order to do this test safely.
-		 */
-		if (!can_use_console(cpu)) {
-			console_locked = 0;
-			wake = 1;
-			retval = 0;
-		}
+	if (!console_trylock())
+		return 0;
+	/*
+	 * If we can't use the console, we need to release the console
+	 * semaphore by hand to avoid flushing the buffer. We need to hold the
+	 * console semaphore in order to do this test safely.
+	 */
+	if (!can_use_console(cpu)) {
+		console_locked = 0;
+		up_console_sem();
+		return 0;
 	}
-	logbuf_cpu = UINT_MAX;
-	raw_spin_unlock(&logbuf_lock);
-	if (wake)
-		up(&console_sem);
-	return retval;
+	return 1;
 }
 
 int printk_delay_msec __read_mostly;
@@ -1392,7 +1511,7 @@ static struct cont {
 	struct task_struct *owner;	/* task of first print*/
 	u64 ts_nsec;			/* time of first print */
 	u8 level;			/* log level of first message */
-	u8 facility;			/* log level of first message */
+	u8 facility;			/* log facility of first message */
 	enum log_flags flags;		/* prefix, newline flags */
 	bool flushed:1;			/* buffer sealed and committed */
 } cont;
@@ -1490,11 +1609,19 @@ asmlinkage int vprintk_emit(int facility, int level,
 	static int recursion_bug;
 	static char textbuf[LOG_LINE_MAX];
 	char *text = textbuf;
-	size_t text_len;
+	size_t text_len = 0;
 	enum log_flags lflags = 0;
 	unsigned long flags;
 	int this_cpu;
 	int printed_len = 0;
+	bool in_sched = false;
+	/* cpu currently holding logbuf_lock in this function */
+	static volatile unsigned int logbuf_cpu = UINT_MAX;
+
+	if (level == SCHED_MESSAGE_LOGLEVEL) {
+		level = -1;
+		in_sched = true;
+	}
 
 	boot_delay_msec(level);
 	printk_delay();
@@ -1516,7 +1643,8 @@ asmlinkage int vprintk_emit(int facility, int level,
 		 */
 		if (!oops_in_progress && !lockdep_recursing(current)) {
 			recursion_bug = 1;
-			goto out_restore_irqs;
+			local_irq_restore(flags);
+			return 0;
 		}
 		zap_locks();
 	}
@@ -1530,17 +1658,22 @@ asmlinkage int vprintk_emit(int facility, int level,
 			"BUG: recent printk recursion!";
 
 		recursion_bug = 0;
-		printed_len += strlen(recursion_msg);
+		text_len = strlen(recursion_msg);
 		/* emit KERN_CRIT message */
-		log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
-			  NULL, 0, recursion_msg, printed_len);
+		printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+					 NULL, 0, recursion_msg, text_len);
 	}
 
 	/*
 	 * The printf needs to come first; we need the syslog
 	 * prefix which might be passed-in as a parameter.
 	 */
-	text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
+	if (in_sched)
+		text_len = scnprintf(text, sizeof(textbuf),
+				     KERN_WARNING "[sched_delayed] ");
+
+	text_len += vscnprintf(text + text_len,
+			       sizeof(textbuf) - text_len, fmt, args);
 
 	/* mark and strip a trailing newline */
 	if (text_len && text[text_len-1] == '\n') {
@@ -1586,9 +1719,12 @@ asmlinkage int vprintk_emit(int facility, int level,
 			cont_flush(LOG_NEWLINE);
 
 		/* buffer line if possible, otherwise store it right away */
-		if (!cont_add(facility, level, text, text_len))
-			log_store(facility, level, lflags | LOG_CONT, 0,
-				  dict, dictlen, text, text_len);
+		if (cont_add(facility, level, text, text_len))
+			printed_len += text_len;
+		else
+			printed_len += log_store(facility, level,
+						 lflags | LOG_CONT, 0,
+						 dict, dictlen, text, text_len);
 	} else {
 		bool stored = false;
 
@@ -1607,27 +1743,39 @@ asmlinkage int vprintk_emit(int facility, int level,
 			cont_flush(LOG_NEWLINE);
 		}
 
-		if (!stored)
-			log_store(facility, level, lflags, 0,
-				  dict, dictlen, text, text_len);
+		if (stored)
+			printed_len += text_len;
+		else
+			printed_len += log_store(facility, level, lflags, 0,
+						 dict, dictlen, text, text_len);
 	}
-	printed_len += text_len;
-
-	/*
-	 * Try to acquire and then immediately release the console semaphore.
-	 * The release will print out buffers and wake up /dev/kmsg and syslog()
-	 * users.
-	 *
-	 * The console_trylock_for_printk() function will release 'logbuf_lock'
-	 * regardless of whether it actually gets the console semaphore or not.
-	 */
-	if (console_trylock_for_printk(this_cpu))
-		console_unlock();
 
+	logbuf_cpu = UINT_MAX;
+	raw_spin_unlock(&logbuf_lock);
 	lockdep_on();
-out_restore_irqs:
 	local_irq_restore(flags);
 
+	/* If called from the scheduler, we can not call up(). */
+	if (!in_sched) {
+		lockdep_off();
+		/*
+		 * Disable preemption to avoid being preempted while holding
+		 * console_sem which would prevent anyone from printing to
+		 * console
+		 */
+		preempt_disable();
+
+		/*
+		 * Try to acquire and then immediately release the console
+		 * semaphore.  The release will print out buffers and wake up
+		 * /dev/kmsg and syslog() users.
+		 */
+		if (console_trylock_for_printk())
+			console_unlock();
+		preempt_enable();
+		lockdep_on();
+	}
+
 	return printed_len;
 }
 EXPORT_SYMBOL(vprintk_emit);
@@ -1699,7 +1847,7 @@ EXPORT_SYMBOL(printk);
 
 #define LOG_LINE_MAX		0
 #define PREFIX_MAX		0
-#define LOG_LINE_MAX 0
+
 static u64 syslog_seq;
 static u32 syslog_idx;
 static u64 console_seq;
@@ -1778,11 +1926,12 @@ static int __add_preferred_console(char *name, int idx, char *options,
 	return 0;
 }
 /*
- * Set up a list of consoles.  Called from init/main.c
+ * Set up a console.  Called via do_early_param() in init/main.c
+ * for each "console=" parameter in the boot command line.
  */
 static int __init console_setup(char *str)
 {
-	char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
+	char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
 	char *s, *options, *brl_options = NULL;
 	int idx;
 
@@ -1799,7 +1948,8 @@ static int __init console_setup(char *str)
 		strncpy(buf, str, sizeof(buf) - 1);
 	}
 	buf[sizeof(buf) - 1] = 0;
-	if ((options = strchr(str, ',')) != NULL)
+	options = strchr(str, ',');
+	if (options)
 		*(options++) = 0;
 #ifdef __sparc__
 	if (!strcmp(str, "ttya"))
@@ -1808,7 +1958,7 @@ static int __init console_setup(char *str)
 		strcpy(buf, "ttyS1");
 #endif
 	for (s = buf; *s; s++)
-		if ((*s >= '0' && *s <= '9') || *s == ',')
+		if (isdigit(*s) || *s == ',')
 			break;
 	idx = simple_strtoul(s, NULL, 10);
 	*s = 0;
@@ -1847,7 +1997,6 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
 	     i++, c++)
 		if (strcmp(c->name, name) == 0 && c->index == idx) {
 			strlcpy(c->name, name_new, sizeof(c->name));
-			c->name[sizeof(c->name) - 1] = 0;
 			c->options = options;
 			c->index = idx_new;
 			return i;
@@ -1856,12 +2005,12 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
 	return -1;
 }
 
-bool console_suspend_enabled = 1;
+bool console_suspend_enabled = true;
 EXPORT_SYMBOL(console_suspend_enabled);
 
 static int __init console_suspend_disable(char *str)
 {
-	console_suspend_enabled = 0;
+	console_suspend_enabled = false;
 	return 1;
 }
 __setup("no_console_suspend", console_suspend_disable);
@@ -1882,16 +2031,14 @@ void suspend_console(void)
 	printk("Suspending console(s) (use no_console_suspend to debug)\n");
 	console_lock();
 	console_suspended = 1;
-	up(&console_sem);
-	mutex_release(&console_lock_dep_map, 1, _RET_IP_);
+	up_console_sem();
 }
 
 void resume_console(void)
 {
 	if (!console_suspend_enabled)
 		return;
-	down(&console_sem);
-	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
+	down_console_sem();
 	console_suspended = 0;
 	console_unlock();
 }
@@ -1933,34 +2080,32 @@ void console_lock(void)
 {
 	might_sleep();
 
-	down(&console_sem);
+	down_console_sem();
 	if (console_suspended)
 		return;
 	console_locked = 1;
 	console_may_schedule = 1;
-	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
 }
 EXPORT_SYMBOL(console_lock);
 
 /**
  * console_trylock - try to lock the console system for exclusive use.
  *
- * Tried to acquire a lock which guarantees that the caller has
- * exclusive access to the console system and the console_drivers list.
+ * Try to acquire a lock which guarantees that the caller has exclusive
+ * access to the console system and the console_drivers list.
  *
  * returns 1 on success, and 0 on failure to acquire the lock.
  */
 int console_trylock(void)
 {
-	if (down_trylock(&console_sem))
+	if (down_trylock_console_sem())
 		return 0;
 	if (console_suspended) {
-		up(&console_sem);
+		up_console_sem();
 		return 0;
 	}
 	console_locked = 1;
 	console_may_schedule = 0;
-	mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
 	return 1;
 }
 EXPORT_SYMBOL(console_trylock);
@@ -2022,7 +2167,7 @@ void console_unlock(void)
 	bool retry;
 
 	if (console_suspended) {
-		up(&console_sem);
+		up_console_sem();
 		return;
 	}
 
@@ -2043,10 +2188,15 @@ again:
 		}
 
 		if (console_seq < log_first_seq) {
+			len = sprintf(text, "** %u printk messages dropped ** ",
+				      (unsigned)(log_first_seq - console_seq));
+
 			/* messages are gone, move to first one */
 			console_seq = log_first_seq;
 			console_idx = log_first_idx;
 			console_prev = 0;
+		} else {
+			len = 0;
 		}
 skip:
 		if (console_seq == log_next_seq)
@@ -2071,8 +2221,8 @@ skip:
 		}
 
 		level = msg->level;
-		len = msg_print_text(msg, console_prev, false,
-				     text, sizeof(text));
+		len += msg_print_text(msg, console_prev, false,
+				      text + len, sizeof(text) - len);
 		console_idx = log_next(console_idx);
 		console_seq++;
 		console_prev = msg->flags;
@@ -2084,7 +2234,6 @@ skip:
 		local_irq_restore(flags);
 	}
 	console_locked = 0;
-	mutex_release(&console_lock_dep_map, 1, _RET_IP_);
 
 	/* Release the exclusive_console once it is used */
 	if (unlikely(exclusive_console))
@@ -2092,7 +2241,7 @@ skip:
 
 	raw_spin_unlock(&logbuf_lock);
 
-	up(&console_sem);
+	up_console_sem();
 
 	/*
 	 * Someone could have filled up the buffer again, so re-check if there's
@@ -2137,7 +2286,7 @@ void console_unblank(void)
 	 * oops_in_progress is set to 1..
 	 */
 	if (oops_in_progress) {
-		if (down_trylock(&console_sem) != 0)
+		if (down_trylock_console_sem() != 0)
 			return;
 	} else
 		console_lock();
@@ -2413,6 +2562,7 @@ int unregister_console(struct console *console)
 	if (console_drivers != NULL && console->flags & CON_CONSDEV)
 		console_drivers->flags |= CON_CONSDEV;
 
+	console->flags &= ~CON_ENABLED;
 	console_unlock();
 	console_sysfs_notify();
 	return res;
@@ -2437,21 +2587,19 @@ late_initcall(printk_late_init);
 /*
  * Delayed printk version, for scheduler-internal messages:
  */
-#define PRINTK_BUF_SIZE		512
-
 #define PRINTK_PENDING_WAKEUP	0x01
-#define PRINTK_PENDING_SCHED	0x02
+#define PRINTK_PENDING_OUTPUT	0x02
 
 static DEFINE_PER_CPU(int, printk_pending);
-static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
 
 static void wake_up_klogd_work_func(struct irq_work *irq_work)
 {
 	int pending = __this_cpu_xchg(printk_pending, 0);
 
-	if (pending & PRINTK_PENDING_SCHED) {
-		char *buf = __get_cpu_var(printk_sched_buf);
-		pr_warn("[sched_delayed] %s", buf);
+	if (pending & PRINTK_PENDING_OUTPUT) {
+		/* If trylock fails, someone else is doing the printing */
+		if (console_trylock())
+			console_unlock();
 	}
 
 	if (pending & PRINTK_PENDING_WAKEUP)
@@ -2473,23 +2621,19 @@ void wake_up_klogd(void)
 	preempt_enable();
 }
 
-int printk_sched(const char *fmt, ...)
+int printk_deferred(const char *fmt, ...)
 {
-	unsigned long flags;
 	va_list args;
-	char *buf;
 	int r;
 
-	local_irq_save(flags);
-	buf = __get_cpu_var(printk_sched_buf);
-
+	preempt_disable();
 	va_start(args, fmt);
-	r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+	r = vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL, NULL, 0, fmt, args);
 	va_end(args);
 
-	__this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+	__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
 	irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
-	local_irq_restore(flags);
+	preempt_enable();
 
 	return r;
 }
@@ -2520,14 +2664,13 @@ EXPORT_SYMBOL(__printk_ratelimit);
 bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 			unsigned int interval_msecs)
 {
-	if (*caller_jiffies == 0
-			|| !time_in_range(jiffies, *caller_jiffies,
-					*caller_jiffies
-					+ msecs_to_jiffies(interval_msecs))) {
-		*caller_jiffies = jiffies;
-		return true;
-	}
-	return false;
+	unsigned long elapsed = jiffies - *caller_jiffies;
+
+	if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs))
+		return false;
+
+	*caller_jiffies = jiffies;
+	return true;
 }
 EXPORT_SYMBOL(printk_timed_ratelimit);