Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
futex: Fix WARN_ON() test for UP
WARN_ON_SMP(): Allow use in if() statements on UP
x86, dumpstack: Use %pB format specifier for stack trace
vsprintf: Introduce %pB format specifier
lockdep: Remove unused 'factor' variable from lockdep_stats_show()

arch/x86/kernel/dumpstack.c

···
 
 void printk_address(unsigned long address, int reliable)
 {
-	printk(" [<%p>] %s%pS\n", (void *) address,
+	printk(" [<%p>] %s%pB\n", (void *) address,
 			reliable ? "" : "? ", (void *) address);
 }
 

include/asm-generic/bug.h

···
 #define WARN_ON_RATELIMIT(condition, state)			\
 		WARN_ON((condition) && __ratelimit(state))
 
+/*
+ * WARN_ON_SMP() is for cases that the warning is either
+ * meaningless for !SMP or may even cause failures.
+ * This is usually used for cases that we have
+ * WARN_ON(!spin_is_locked(&lock)) checks, as spin_is_locked()
+ * returns 0 for uniprocessor settings.
+ * It can also be used with values that are only defined
+ * on SMP:
+ *
+ * struct foo {
+ *  [...]
+ * #ifdef CONFIG_SMP
+ *	int bar;
+ * #endif
+ * };
+ *
+ * void func(struct foo *zoot)
+ * {
+ *	WARN_ON_SMP(!zoot->bar);
+ *
+ * For CONFIG_SMP, WARN_ON_SMP() should act the same as WARN_ON(),
+ * and should be a nop and return false for uniprocessor.
+ *
+ * if (WARN_ON_SMP(x)) returns true only when CONFIG_SMP is set
+ * and x is true.
+ */
 #ifdef CONFIG_SMP
 # define WARN_ON_SMP(x)			WARN_ON(x)
 #else
-# define WARN_ON_SMP(x)			do { } while (0)
+# define WARN_ON_SMP(x)			({0;})
 #endif
 
 #endif

include/linux/kallsyms.h

···
 
 /* Look up a kernel symbol and return it in a text buffer. */
 extern int sprint_symbol(char *buffer, unsigned long address);
+extern int sprint_backtrace(char *buffer, unsigned long address);
 
 /* Look up a kernel symbol and print it to the kernel messages. */
 extern void __print_symbol(const char *fmt, unsigned long address);
···
 }
 
 static inline int sprint_symbol(char *buffer, unsigned long addr)
+{
+	*buffer = '\0';
+	return 0;
+}
+
+static inline int sprint_backtrace(char *buffer, unsigned long addr)
 {
 	*buffer = '\0';
 	return 0;

kernel/futex.c

···
 {
 	struct futex_hash_bucket *hb;
 
-	if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr)
-			|| plist_node_empty(&q->list)))
+	if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr))
+	    || WARN_ON(plist_node_empty(&q->list)))
 		return;
 
 	hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock);

kernel/kallsyms.c

···
 }
 
 /* Look up a kernel symbol and return it in a text buffer. */
-int sprint_symbol(char *buffer, unsigned long address)
+static int __sprint_symbol(char *buffer, unsigned long address,
+			   int symbol_offset)
 {
 	char *modname;
 	const char *name;
 	unsigned long offset, size;
 	int len;
 
+	address += symbol_offset;
 	name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
 	if (!name)
 		return sprintf(buffer, "0x%lx", address);
···
 		strcpy(buffer, name);
 	len = strlen(buffer);
 	buffer += len;
+	offset -= symbol_offset;
 
 	if (modname)
-		len += sprintf(buffer, "+%#lx/%#lx [%s]",
-						offset, size, modname);
+		len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname);
 	else
 		len += sprintf(buffer, "+%#lx/%#lx", offset, size);
 
 	return len;
 }
+
+/**
+ * sprint_symbol - Look up a kernel symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function looks up a kernel symbol with @address and stores its name,
+ * offset, size and module name to @buffer if possible. If no symbol was found,
+ * just saves its @address as is.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_symbol(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, 0);
+}
+
 EXPORT_SYMBOL_GPL(sprint_symbol);
+
+/**
+ * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function is for stack backtrace and does the same thing as
+ * sprint_symbol() but with modified/decreased @address. If there is a
+ * tail-call to the function marked "noreturn", gcc optimized out code after
+ * the call so that the stack-saved return address could point outside of the
+ * caller. This function ensures that kallsyms will find the original caller
+ * by decreasing @address.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_backtrace(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, -1);
+}
 
 /* Look up a kernel symbol and print it to the kernel messages. */
 void __print_symbol(const char *fmt, unsigned long address)

kernel/lockdep_proc.c

···
 		      nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 		      nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 		      nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
-		      sum_forward_deps = 0, factor = 0;
+		      sum_forward_deps = 0;
 
 	list_for_each_entry(class, &all_lock_classes, lock_entry) {
 
···
 			nr_irq_unsafe * nr_irq_safe +
 			nr_hardirq_unsafe * nr_hardirq_safe +
 			nr_list_entries);
-
-	/*
-	 * Estimated factor between direct and indirect
-	 * dependencies:
-	 */
-	if (nr_list_entries)
-		factor = sum_forward_deps / nr_list_entries;
 
 #ifdef CONFIG_PROVE_LOCKING
 	seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",

lib/vsprintf.c

···
 	unsigned long value = (unsigned long) ptr;
 #ifdef CONFIG_KALLSYMS
 	char sym[KSYM_SYMBOL_LEN];
-	if (ext != 'f' && ext != 's')
+	if (ext == 'B')
+		sprint_backtrace(sym, value);
+	else if (ext != 'f' && ext != 's')
 		sprint_symbol(sym, value);
 	else
 		kallsyms_lookup(value, NULL, NULL, NULL, sym);
···
  * - 'f' For simple symbolic function names without offset
  * - 'S' For symbolic direct pointers with offset
  * - 's' For symbolic direct pointers without offset
+ * - 'B' For backtraced symbolic direct pointers with offset
  * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
  * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
  * - 'M' For a 6-byte MAC address, it prints the address in the
···
 		/* Fallthrough */
 	case 'S':
 	case 's':
+	case 'B':
 		return symbol_string(buf, end, ptr, spec, *fmt);
 	case 'R':
 	case 'r':
···
  * %ps output the name of a text symbol without offset
  * %pF output the name of a function pointer with its offset
  * %pf output the name of a function pointer without its offset
+ * %pB output the name of a backtrace symbol with its offset
  * %pR output the address range in a struct resource with decoded flags
  * %pr output the address range in a struct resource with raw flags
  * %pM output a 6-byte MAC address with colons