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Commit 30c00eda authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Jens Axboe
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block: blk_rq_map_kern uses the bounce buffers for stack buffers 



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: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 27f8221a

block/blk-map.c

+5 −0
Original line number Diff line number Diff line
@@ -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