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authorFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>2009-02-27 17:35:43 +0900
committerJeff Garzik <jgarzik@redhat.com>2009-03-05 07:24:57 -0500
commit5825627c9463581fd9e70f8285685889ae5bb9bb (patch)
tree321a20a0e25aee8f32254b13730f423f6b434486
parente7d3ef13d52a126438f687a1a32da65ff926ed57 (diff)
downloadlinux-5825627c9463581fd9e70f8285685889ae5bb9bb.tar.gz
libata: fix dma_unmap_sg misuse
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>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
-rw-r--r--drivers/ata/libata-core.c4
-rw-r--r--include/linux/libata.h1
2 files changed, 3 insertions, 2 deletions
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 9fbf0595f3d4..5e324cea3019 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4612,7 +4612,7 @@ void ata_sg_clean(struct ata_queued_cmd *qc)
 	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_queued_cmd *qc)
 		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 --git a/include/linux/libata.h b/include/linux/libata.h
index dd818c7decd7..fbf064e13ad5 100644
--- a/include/linux/libata.h
+++ b/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;