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

Pull stack trace updates from Ingo Molnar:
 "So Thomas looked at the stacktrace code recently and noticed a few
  weirdnesses, and we all know how such stories of crummy kernel code
  meeting German engineering perfection end: a 45-patch series to clean
  it all up! :-)

  Here's the changes in Thomas's words:

   'Struct stack_trace is a sinkhole for input and output parameters
    which is largely pointless for most usage sites. In fact if embedded
    into other data structures it creates indirections and extra storage
    overhead for no benefit.

    Looking at all usage sites makes it clear that they just require an
    interface which is based on a storage array. That array is either on
    stack, global or embedded into some other data structure.

    Some of the stack depot usage sites are outright wrong, but
    fortunately the wrongness just causes more stack being used for
    nothing and does not have functional impact.

    Another oddity is the inconsistent termination of the stack trace
    with ULONG_MAX. It's pointless as the number of entries is what
    determines the length of the stored trace. In fact quite some call
    sites remove the ULONG_MAX marker afterwards with or without nasty
    comments about it. Not all architectures do that and those which do,
    do it inconsistenly either conditional on nr_entries == 0 or
    unconditionally.

    The following series cleans that up by:

      1) Removing the ULONG_MAX termination in the architecture code

      2) Removing the ULONG_MAX fixups at the call sites

      3) Providing plain storage array based interfaces for stacktrace
         and stackdepot.

      4) Cleaning up the mess at the callsites including some related
         cleanups.

      5) Removing the struct stack_trace based interfaces

    This is not changing the struct stack_trace interfaces at the
    architecture level, but it removes the exposure to the generic
    code'"

* 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits)
  x86/stacktrace: Use common infrastructure
  stacktrace: Provide common infrastructure
  lib/stackdepot: Remove obsolete functions
  stacktrace: Remove obsolete functions
  livepatch: Simplify stack trace retrieval
  tracing: Remove the last struct stack_trace usage
  tracing: Simplify stack trace retrieval
  tracing: Make ftrace_trace_userstack() static and conditional
  tracing: Use percpu stack trace buffer more intelligently
  tracing: Simplify stacktrace retrieval in histograms
  lockdep: Simplify stack trace handling
  lockdep: Remove save argument from check_prev_add()
  lockdep: Remove unused trace argument from print_circular_bug()
  drm: Simplify stacktrace handling
  dm persistent data: Simplify stack trace handling
  dm bufio: Simplify stack trace retrieval
  btrfs: ref-verify: Simplify stack trace retrieval
  dma/debug: Simplify stracktrace retrieval
  fault-inject: Simplify stacktrace retrieval
  mm/page_owner: Simplify stack trace handling
  ...

4 files changed, 80 insertions, 36 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 730876187344..20899919ead8 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -241,21 +241,11 @@ static inline void ftrace_free_mem(struct module *mod, void *start, void *end) {
 
 #ifdef CONFIG_STACK_TRACER
 
-#define STACK_TRACE_ENTRIES 500
-
-struct stack_trace;
-
-extern unsigned stack_trace_index[];
-extern struct stack_trace stack_trace_max;
-extern unsigned long stack_trace_max_size;
-extern arch_spinlock_t stack_trace_max_lock;
-
 extern int stack_tracer_enabled;
-void stack_trace_print(void);
-int
-stack_trace_sysctl(struct ctl_table *table, int write,
-		   void __user *buffer, size_t *lenp,
-		   loff_t *ppos);
+
+int stack_trace_sysctl(struct ctl_table *table, int write,
+		       void __user *buffer, size_t *lenp,
+		       loff_t *ppos);
 
 /* DO NOT MODIFY THIS VARIABLE DIRECTLY! */
 DECLARE_PER_CPU(int, disable_stack_tracer);
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 79c3873d58ac..6f165d625320 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -66,6 +66,11 @@ struct lock_class_key {
 
 extern struct lock_class_key __lockdep_no_validate__;
 
+struct lock_trace {
+	unsigned int		nr_entries;
+	unsigned int		offset;
+};
+
 #define LOCKSTAT_POINTS		4
 
 /*
@@ -100,7 +105,7 @@ struct lock_class {
 	 * IRQ/softirq usage tracking bits:
 	 */
 	unsigned long			usage_mask;
-	struct stack_trace		usage_traces[XXX_LOCK_USAGE_STATES];
+	struct lock_trace		usage_traces[XXX_LOCK_USAGE_STATES];
 
 	/*
 	 * Generation counter, when doing certain classes of graph walking,
@@ -188,7 +193,7 @@ struct lock_list {
 	struct list_head		entry;
 	struct lock_class		*class;
 	struct lock_class		*links_to;
-	struct stack_trace		trace;
+	struct lock_trace		trace;
 	int				distance;
 
 	/*
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 7978b3e2c1e1..0805dee1b6b8 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -23,10 +23,10 @@
 
 typedef u32 depot_stack_handle_t;
 
-struct stack_trace;
+depot_stack_handle_t stack_depot_save(unsigned long *entries,
+				      unsigned int nr_entries, gfp_t gfp_flags);
 
-depot_stack_handle_t depot_save_stack(struct stack_trace *trace, gfp_t flags);
-
-void depot_fetch_stack(depot_stack_handle_t handle, struct stack_trace *trace);
+unsigned int stack_depot_fetch(depot_stack_handle_t handle,
+			       unsigned long **entries);
 
 #endif
diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index ba29a0613e66..f0cfd12cb45e 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -3,11 +3,64 @@
 #define __LINUX_STACKTRACE_H
 
 #include <linux/types.h>
+#include <asm/errno.h>
 
 struct task_struct;
 struct pt_regs;
 
 #ifdef CONFIG_STACKTRACE
+void stack_trace_print(unsigned long *trace, unsigned int nr_entries,
+		       int spaces);
+int stack_trace_snprint(char *buf, size_t size, unsigned long *entries,
+			unsigned int nr_entries, int spaces);
+unsigned int stack_trace_save(unsigned long *store, unsigned int size,
+			      unsigned int skipnr);
+unsigned int stack_trace_save_tsk(struct task_struct *task,
+				  unsigned long *store, unsigned int size,
+				  unsigned int skipnr);
+unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
+				   unsigned int size, unsigned int skipnr);
+unsigned int stack_trace_save_user(unsigned long *store, unsigned int size);
+
+/* Internal interfaces. Do not use in generic code */
+#ifdef CONFIG_ARCH_STACKWALK
+
+/**
+ * stack_trace_consume_fn - Callback for arch_stack_walk()
+ * @cookie:	Caller supplied pointer handed back by arch_stack_walk()
+ * @addr:	The stack entry address to consume
+ * @reliable:	True when the stack entry is reliable. Required by
+ *		some printk based consumers.
+ *
+ * Return:	True, if the entry was consumed or skipped
+ *		False, if there is no space left to store
+ */
+typedef bool (*stack_trace_consume_fn)(void *cookie, unsigned long addr,
+				       bool reliable);
+/**
+ * arch_stack_walk - Architecture specific function to walk the stack
+ * @consume_entry:	Callback which is invoked by the architecture code for
+ *			each entry.
+ * @cookie:		Caller supplied pointer which is handed back to
+ *			@consume_entry
+ * @task:		Pointer to a task struct, can be NULL
+ * @regs:		Pointer to registers, can be NULL
+ *
+ * ============ ======= ============================================
+ * task	        regs
+ * ============ ======= ============================================
+ * task		NULL	Stack trace from task (can be current)
+ * current	regs	Stack trace starting on regs->stackpointer
+ * ============ ======= ============================================
+ */
+void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+		     struct task_struct *task, struct pt_regs *regs);
+int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, void *cookie,
+			     struct task_struct *task);
+void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
+			  const struct pt_regs *regs);
+
+#else /* CONFIG_ARCH_STACKWALK */
 struct stack_trace {
 	unsigned int nr_entries, max_entries;
 	unsigned long *entries;
@@ -21,24 +74,20 @@ extern void save_stack_trace_tsk(struct task_struct *tsk,
 				struct stack_trace *trace);
 extern int save_stack_trace_tsk_reliable(struct task_struct *tsk,
 					 struct stack_trace *trace);
-
-extern void print_stack_trace(struct stack_trace *trace, int spaces);
-extern int snprint_stack_trace(char *buf, size_t size,
-			struct stack_trace *trace, int spaces);
-
-#ifdef CONFIG_USER_STACKTRACE_SUPPORT
 extern void save_stack_trace_user(struct stack_trace *trace);
+#endif /* !CONFIG_ARCH_STACKWALK */
+#endif /* CONFIG_STACKTRACE */
+
+#if defined(CONFIG_STACKTRACE) && defined(CONFIG_HAVE_RELIABLE_STACKTRACE)
+int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
+				  unsigned int size);
 #else
-# define save_stack_trace_user(trace)              do { } while (0)
+static inline int stack_trace_save_tsk_reliable(struct task_struct *tsk,
+						unsigned long *store,
+						unsigned int size)
+{
+	return -ENOSYS;
+}
 #endif
 
-#else /* !CONFIG_STACKTRACE */
-# define save_stack_trace(trace)			do { } while (0)
-# define save_stack_trace_tsk(tsk, trace)		do { } while (0)
-# define save_stack_trace_user(trace)			do { } while (0)
-# define print_stack_trace(trace, spaces)		do { } while (0)
-# define snprint_stack_trace(buf, size, trace, spaces)	do { } while (0)
-# define save_stack_trace_tsk_reliable(tsk, trace)	({ -ENOSYS; })
-#endif /* CONFIG_STACKTRACE */
-
 #endif /* __LINUX_STACKTRACE_H */