This is a repost of: http://marc.info/?l=linux-ide&m=123484533504307&w=2 I sent this 10 days ago but seems that I can't find this in linux-next yet. I guess that all the IOMMUs can handle this misuse for now so it's not urgent. = From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> Subject: [PATCH] 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@xxxxxxxxxxxxx> Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> --- drivers/ata/libata-core.c | 4 ++-- include/linux/libata.h | 1 + 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 8167381..17a274a 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 c953e17..337d1bd 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; -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
