Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7c31190b authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
Browse files

lib/stackdepot: avoid to return 0 handle 

Recently, we allow to save the stacktrace whose hashed value is 0.  It
causes the problem that stackdepot could return 0 even if in success.
User of stackdepot cannot distinguish whether it is success or not so we
need to solve this problem.  In this patch, 1 bit are added to handle
and make valid handle none 0 by setting this bit.  After that, valid
handle will not be 0 and 0 handle will represent failure correctly.

Fixes: 33334e25 ("lib/stackdepot.c: allow the stack trace hash to be zero")
Link: http://lkml.kernel.org/r/1462252403-1106-1-git-send-email-iamjoonsoo.kim@lge.com


Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 172400c6

lib/stackdepot.c

+5 −1
Original line number Diff line number Diff line
@@ -42,12 +42,14 @@ 


#define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8)



#define STACK_ALLOC_NULL_PROTECTION_BITS 1

#define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */

#define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER))

#define STACK_ALLOC_ALIGN 4

#define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \

					STACK_ALLOC_ALIGN)

#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - STACK_ALLOC_OFFSET_BITS)

#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \

		STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS)

#define STACK_ALLOC_SLABS_CAP 1024

#define STACK_ALLOC_MAX_SLABS \

	(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
@@ -59,6 +61,7 @@ union handle_parts { 
	struct {

		u32 slabindex : STACK_ALLOC_INDEX_BITS;

		u32 offset : STACK_ALLOC_OFFSET_BITS;

		u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;

	};

};
@@ -136,6 +139,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, 
	stack->size = size;

	stack->handle.slabindex = depot_index;

	stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;

	stack->handle.valid = 1;

	memcpy(stack->entries, entries, size * sizeof(unsigned long));

	depot_offset += required_size;