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| author | Tejun Heo <htejun@gmail.com> | 2006-02-20 23:48:38 +0900 |
|---|---|---|
| committer | Jeff Garzik <jgarzik@pobox.com> | 2006-02-20 16:48:18 -0500 |
| commit | 2e242fa994428bd1a40b6a7e97430413246d0a16 (patch) | |
| tree | 8ba101ac6b2f9d6e5d14eebb9091d43c9177626c /drivers/scsi | |
| parent | cc1887f3d8ae8ea61efa1a75af8ec0467b9dd546 (diff) | |
| download | lwn-2e242fa994428bd1a40b6a7e97430413246d0a16.tar.gz lwn-2e242fa994428bd1a40b6a7e97430413246d0a16.zip | |
[PATCH] libata: make ata_sg_setup_one() trim zero length sg
This patch makes ata_sg_setup_one() trim sg entry (thus making
qc->n_elem zero) if padding results in zero length sg entry.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Diffstat (limited to 'drivers/scsi')
| -rw-r--r-- | drivers/scsi/libata-core.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c index bbac87a13d57..5f1d7580218d 100644 --- a/drivers/scsi/libata-core.c +++ b/drivers/scsi/libata-core.c @@ -2514,7 +2514,7 @@ static void ata_sg_clean(struct ata_queued_cmd *qc) assert(sg != NULL); if (qc->flags & ATA_QCFLAG_SINGLE) - assert(qc->n_elem == 1); + assert(qc->n_elem <= 1); VPRINTK("unmapping %u sg elements\n", qc->n_elem); @@ -2537,7 +2537,7 @@ static void ata_sg_clean(struct ata_queued_cmd *qc) kunmap_atomic(addr, KM_IRQ0); } } else { - if (sg_dma_len(&sg[0]) > 0) + if (qc->n_elem) dma_unmap_single(ap->host_set->dev, sg_dma_address(&sg[0]), sg_dma_len(&sg[0]), dir); @@ -2715,6 +2715,7 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc) int dir = qc->dma_dir; struct scatterlist *sg = qc->__sg; dma_addr_t dma_address; + int trim_sg = 0; /* we must lengthen transfers to end on a 32-bit boundary */ qc->pad_len = sg->length & 3; @@ -2734,13 +2735,15 @@ static int ata_sg_setup_one(struct ata_queued_cmd *qc) sg_dma_len(psg) = ATA_DMA_PAD_SZ; /* trim sg */ sg->length -= qc->pad_len; + if (sg->length == 0) + trim_sg = 1; DPRINTK("padding done, sg->length=%u pad_len=%u\n", sg->length, qc->pad_len); } - if (!sg->length) { - sg_dma_address(sg) = 0; + if (trim_sg) { + qc->n_elem--; goto skip_map; } @@ -2753,9 +2756,9 @@ 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; +skip_map: DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg), qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read"); |