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[libata] fix bugs in ATAPI padding DMA mapping code 

The ATAPI pad-to-next-32bit-boundary code modifies the scatterlist's
length variable, sometimes to zero.  x86-64 platform would oops if a
zero-length scatterlist entry was asked to be mapped.  Work around this
by ensuring that we never DMA-map a zero length buffer or SG entry.
This commit is contained in:
Jeff Garzik 2005-11-14 14:06:26 -05:00
parent ad36d1a533
commit e1410f2d95
1 changed files with 26 additions and 5 deletions
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31
drivers/scsi/libata-core.c
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@ -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;