On Tue, 03 Jun 2008 14:55:15 -0700 akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > The patch titled > block: blk_rq_map_kern uses the bounce buffers for stack buffers > has been added to the -mm tree. Its filename is > block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers.patch > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/SubmitChecklist when testing your code *** > > See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find > out what to do about this > > The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ > > ------------------------------------------------------ > Subject: block: blk_rq_map_kern uses the bounce buffers for stack buffers > From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> > > 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 <fujita.tomonori@xxxxxxxxxxxxx> > Cc: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx> > Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> > Cc: Tejun Heo <htejun@xxxxxxxxx> > Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> > Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > block/blk-map.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff -puN block/blk-map.c~block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers block/blk-map.c > --- a/block/blk-map.c~block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers > +++ a/block/blk-map.c > @@ -268,6 +268,7 @@ int blk_rq_map_kern(struct request_queue > 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; > @@ -278,6 +279,10 @@ int blk_rq_map_kern(struct request_queue > 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 Here's an updated version. A helper function to test if an object is on the stack was added into -mm. We can use it to simplify this patch. http://marc.info/?l=linux-kernel&m=121315043731994&w=2 = From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> Subject: [PATCH] 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: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> --- block/blk-map.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/block/blk-map.c b/block/blk-map.c index 0b1af5a..3cec2b1 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -276,7 +276,8 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, kaddr = (unsigned long)kbuf; alignment = queue_dma_alignment(q) | q->dma_pad_mask; - do_copy = ((kaddr & alignment) || (len & alignment)); + do_copy = ((kaddr & alignment) || (len & alignment) || + object_is_on_stack(kbuf)); if (do_copy) bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); -- 1.5.5.GIT -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
