diff options
| -rw-r--r-- | drivers/scsi/libata-core.c | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c index d81db3a3d4b9..1ccaf467d516 100644 --- a/drivers/scsi/libata-core.c +++ b/drivers/scsi/libata-core.c @@ -2409,7 +2409,8 @@ static void ata_sg_clean(struct ata_queued_cmd *qc) pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ); if (qc->flags & ATA_QCFLAG_SG) { - dma_unmap_sg(ap->host_set->dev, sg, qc->n_elem, dir); + if (qc->n_elem) + dma_unmap_sg(ap->host_set->dev, sg, qc->n_elem, dir); /* restore last sg */ sg[qc->orig_n_elem - 1].length += qc->pad_len; if (pad_buf) { @@ -2419,8 +2420,10 @@ static void ata_sg_clean(struct ata_queued_cmd *qc) kunmap_atomic(psg->page, KM_IRQ0); } } else { - dma_unmap_single(ap->host_set->dev, sg_dma_address(&sg[0]), - sg_dma_len(&sg[0]), dir); + if (sg_dma_len(&sg[0]) > 0) + dma_unmap_single(ap->host_set->dev, + sg_dma_address(&sg[0]), sg_dma_len(&sg[0]), + dir); /* restore sg */ sg->length += qc->pad_len; if (pad_buf) @@ -2619,6 +2622,11 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc) sg->length, qc->pad_len); } + if (!sg->length) { + sg_dma_address(sg) = 0; + goto skip_map; + } + dma_address = dma_map_single(ap->host_set->dev, qc->buf_virt, sg->length, dir); if (dma_mapping_error(dma_address)) { @@ -2628,6 +2636,7 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc) } sg_dma_address(sg) = dma_address; +skip_map: sg_dma_len(sg) = sg->length; DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg), @@ -2655,7 +2664,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) struct ata_port *ap = qc->ap; struct scatterlist *sg = qc->__sg; struct scatterlist *lsg = &sg[qc->n_elem - 1]; - int n_elem, dir; + int n_elem, pre_n_elem, dir, trim_sg = 0; VPRINTK("ENTER, ata%u\n", ap->id); assert(qc->flags & ATA_QCFLAG_SG); @@ -2689,13 +2698,24 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) sg_dma_len(psg) = ATA_DMA_PAD_SZ; /* trim last sg */ lsg->length -= qc->pad_len; + if (lsg->length == 0) + trim_sg = 1; DPRINTK("padding done, sg[%d].length=%u pad_len=%u\n", qc->n_elem - 1, lsg->length, qc->pad_len); } + pre_n_elem = qc->n_elem; + if (trim_sg && pre_n_elem) + pre_n_elem--; + + if (!pre_n_elem) { + n_elem = 0; + goto skip_map; + } + dir = qc->dma_dir; - n_elem = dma_map_sg(ap->host_set->dev, sg, qc->n_elem, dir); + n_elem = dma_map_sg(ap->host_set->dev, sg, pre_n_elem, dir); if (n_elem < 1) { /* restore last sg */ lsg->length += qc->pad_len; @@ -2704,6 +2724,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) DPRINTK("%d sg elements mapped\n", n_elem); +skip_map: qc->n_elem = n_elem; return 0; |