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block: blk_rq_map_kern uses the bounce buffers for stack buffers

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blk_rq_map_kern is used for kernel internal I/Os. Some callers use
this function with stack buffers but DMA to/from the stack buffers
leads to memory corruption on a non-coherent platform.

This patch make blk_rq_map_kern uses the bounce buffers if a caller
passes a stack buffer (on the all platforms for simplicity).

Signed-off-by: FUJITA Tomonori <[email protected]>
Cc: Bartlomiej Zolnierkiewicz <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: James Bottomley <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
FUJITA Tomonori 2008-07-04 09:31:11 +02:00 • committed by Jens Axboe
commit 30c00eda73
1 changed files with 5 additions and 0 deletions
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5
block/blk-map.c
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@ -269,6 +269,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
int reading = rq_data_dir(rq) == READ;
int do_copy = 0;
struct bio *bio;
unsigned long stack_mask = ~(THREAD_SIZE - 1);
if (len > (q->max_hw_sectors << 9))
return -EINVAL;
@ -279,6 +280,10 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
alignment = queue_dma_alignment(q) | q->dma_pad_mask;
do_copy = ((kaddr & alignment) || (len & alignment));
if (!((kaddr & stack_mask) ^
((unsigned long)current->stack & stack_mask)))
do_copy = 1;
if (do_copy)
bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
else