lib, stackdepot: add helper to print stack entries into buffer

To print stack entries into a buffer, users of stackdepot, first get a
list of stack entries using stack_depot_fetch and then print this list
into a buffer using stack_trace_snprint.  Provide a helper in stackdepot
for this purpose.  Also change above mentioned users to use this helper.

[[email protected]: fix build error]
  Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: export stack_depot_snprint() to modules]
  Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Imran Khan <[email protected]>
Suggested-by: Vlastimil Babka <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Jani Nikula <[email protected]>	[i915]
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Thomas Zimmermann <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 25 insertions, 0 deletions

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 4e1f2982d0fa..b437ae79aca1 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -214,6 +214,31 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
 }
 
 /**
+ * stack_depot_snprint - print stack entries from a depot into a buffer
+ *
+ * @handle:	Stack depot handle which was returned from
+ *		stack_depot_save().
+ * @buf:	Pointer to the print buffer
+ *
+ * @size:	Size of the print buffer
+ *
+ * @spaces:	Number of leading spaces to print
+ *
+ * Return:	Number of bytes printed.
+ */
+int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
+		       int spaces)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(handle, &entries);
+	return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries,
+						spaces) : 0;
+}
+EXPORT_SYMBOL_GPL(stack_depot_snprint);
+
+/**
  * stack_depot_print - print stack entries from a depot
  *
  * @stack:		Stack depot handle which was returned from