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List:       linux-mm-commits
Subject:    + libata-fix-dma_unmap_sg-misuse.patch added to -mm tree
From:       akpm () linux-foundation ! org
Date:       2009-02-27 19:56:05
Message-ID: 200902271956.n1RJu5eh028965 () imap1 ! linux-foundation ! org
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The patch titled
     libata: fix dma_unmap_sg misuse
has been added to the -mm tree.  Its filename is
     libata-fix-dma_unmap_sg-misuse.patch

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*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/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: libata: fix dma_unmap_sg misuse
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

libata passes the returned value of dma_map_sg() to dma_unmap_sg(),which
is the misuse of dma_unmap_sg().

DMA-mapping.txt says:

To unmap a scatterlist, just call:

	pci_unmap_sg(pdev, sglist, nents, direction);

Again, make sure DMA activity has already finished.

PLEASE NOTE:  The 'nents' argument to the pci_unmap_sg call must be
              the _same_ one you passed into the pci_map_sg call,
	      it should _NOT_ be the 'count' value _returned_ from the
              pci_map_sg call.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/ata/libata-core.c |    4 ++--
 include/linux/libata.h    |    1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff -puN drivers/ata/libata-core.c~libata-fix-dma_unmap_sg-misuse drivers/ata/libata-core.c
--- a/drivers/ata/libata-core.c~libata-fix-dma_unmap_sg-misuse
+++ a/drivers/ata/libata-core.c
@@ -4612,7 +4612,7 @@ void ata_sg_clean(struct ata_queued_cmd 
 	VPRINTK("unmapping %u sg elements\n", qc->n_elem);
 
 	if (qc->n_elem)
-		dma_unmap_sg(ap->dev, sg, qc->n_elem, dir);
+		dma_unmap_sg(ap->dev, sg, qc->orig_n_elem, dir);
 
 	qc->flags &= ~ATA_QCFLAG_DMAMAP;
 	qc->sg = NULL;
@@ -4727,7 +4727,7 @@ static int ata_sg_setup(struct ata_queue
 		return -1;
 
 	DPRINTK("%d sg elements mapped\n", n_elem);
-
+	qc->orig_n_elem = qc->n_elem;
 	qc->n_elem = n_elem;
 	qc->flags |= ATA_QCFLAG_DMAMAP;
 
diff -puN include/linux/libata.h~libata-fix-dma_unmap_sg-misuse include/linux/libata.h
--- a/include/linux/libata.h~libata-fix-dma_unmap_sg-misuse
+++ a/include/linux/libata.h
@@ -530,6 +530,7 @@ struct ata_queued_cmd {
 	unsigned long		flags;		/* ATA_QCFLAG_xxx */
 	unsigned int		tag;
 	unsigned int		n_elem;
+	unsigned int		orig_n_elem;
 
 	int			dma_dir;
 
_

Patches currently in -mm which might be from fujita.tomonori@lab.ntt.co.jp are

linux-next.patch
libata-fix-dma_unmap_sg-misuse.patch
sg_io-dont-perform-unneeded-copy-in-compat-code.patch
remove-unused-include-asm-generic-dma-mappingh.patch

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