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Subject[PATCH 7/19] TuxOnIce: Modify swsusp bitmaps to allow modification during scanning.
Date
The version of the bitmap code currently in vanilla uses one struct
bm_position only. This prevents code from modifying a bitmap while
iterating through it. Add an extra struct bm_position and use it in
memory_bm_next_pfn so that this is no longer an issue.

Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>
---
kernel/power/power.h | 3 +++
kernel/power/snapshot.c | 13 ++++++++-----
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/kernel/power/power.h b/kernel/power/power.h
index ce81df1..4cc59d5 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -287,6 +287,9 @@ struct memory_bitmap {
* objects
*/
struct bm_position cur; /* most recently used bit position */
+ struct bm_position iter; /* most recently used bit position
+ * when iterating over a bitmap.
+ */
};

extern int memory_bm_create(struct memory_bitmap *bm, gfp_t gfp_mask,
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 8020644..786227c 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -234,6 +234,9 @@ void memory_bm_position_reset(struct memory_bitmap *bm)
{
bm->cur.block = list_entry(bm->blocks.next, struct bm_block, hook);
bm->cur.bit = 0;
+
+ bm->iter.block = list_entry(bm->blocks.next, struct bm_block, hook);
+ bm->iter.bit = 0;
}

/**
@@ -519,23 +522,23 @@ unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
struct bm_block *bb;
int bit;

- bb = bm->cur.block;
+ bb = bm->iter.block;
do {
- bit = bm->cur.bit;
+ bit = bm->iter.bit;
bit = find_next_bit(bb->data, bm_block_bits(bb), bit);
if (bit < bm_block_bits(bb))
goto Return_pfn;

bb = list_entry(bb->hook.next, struct bm_block, hook);
- bm->cur.block = bb;
- bm->cur.bit = 0;
+ bm->iter.block = bb;
+ bm->iter.bit = 0;
} while (&bb->hook != &bm->blocks);

memory_bm_position_reset(bm);
return BM_END_OF_MAP;

Return_pfn:
- bm->cur.bit = bit + 1;
+ bm->iter.bit = bit + 1;
return bb->start_pfn + bit;
}

--
1.5.6.3


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