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authorTejun Heo <htejun@gmail.com>2006-02-20 23:48:38 +0900
committerJeff Garzik <jgarzik@pobox.com>2006-02-20 16:48:18 -0500
commit2e242fa994428bd1a40b6a7e97430413246d0a16 (patch)
tree8ba101ac6b2f9d6e5d14eebb9091d43c9177626c
parentcc1887f3d8ae8ea61efa1a75af8ec0467b9dd546 (diff)
[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>
-rw-r--r--drivers/scsi/libata-core.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index bbac87a13d5..5f1d7580218 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");