libata: change ATA_QCFLAG_DMAMAP semantics
ATA_QCFLAG_DMAMAP was a bit peculiar in that it got set during qc initialization and cleared if DMA mapping wasn't necessary. Make it more straight forward by making the following changes. * Don't set it during initialization. Set it after DMA is actually mapped. * Add BUG_ON() to guarantee that there is data to transfer if DMAMAP is set. This always holds for the current code. The BUG_ON() is for docummentation and sanity check. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
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@ -4475,7 +4475,6 @@ void ata_sg_clean(struct ata_queued_cmd *qc)
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int dir = qc->dma_dir;
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void *pad_buf = NULL;
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WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));
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WARN_ON(sg == NULL);
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VPRINTK("unmapping %u sg elements\n", qc->n_elem);
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@ -4762,11 +4761,9 @@ void ata_noop_qc_prep(struct ata_queued_cmd *qc) { }
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* LOCKING:
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* spin_lock_irqsave(host lock)
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*/
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void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
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unsigned int n_elem)
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{
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qc->flags |= ATA_QCFLAG_DMAMAP;
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qc->__sg = sg;
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qc->n_elem = n_elem;
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qc->orig_n_elem = n_elem;
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@ -4795,7 +4792,6 @@ static int ata_sg_setup(struct ata_queued_cmd *qc)
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int n_elem, pre_n_elem, dir, trim_sg = 0;
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VPRINTK("ENTER, ata%u\n", ap->print_id);
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WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));
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/* we must lengthen transfers to end on a 32-bit boundary */
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qc->pad_len = lsg->length & 3;
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@ -4855,6 +4851,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc)
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skip_map:
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qc->n_elem = n_elem;
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qc->flags |= ATA_QCFLAG_DMAMAP;
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return 0;
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}
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@ -5912,12 +5909,15 @@ void ata_qc_issue(struct ata_queued_cmd *qc)
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qc->flags |= ATA_QCFLAG_ACTIVE;
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ap->qc_active |= 1 << qc->tag;
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/* We guarantee to LLDs that they will have at least one
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* non-zero sg if the command is a data command.
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*/
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BUG_ON(ata_is_data(prot) && (!qc->__sg || !qc->n_elem || !qc->nbytes));
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if (ata_is_dma(prot) || (ata_is_pio(prot) &&
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(ap->flags & ATA_FLAG_PIO_DMA))) {
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(ap->flags & ATA_FLAG_PIO_DMA)))
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if (ata_sg_setup(qc))
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goto sg_err;
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} else
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qc->flags &= ATA_QCFLAG_DMAMAP;
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/* if device is sleeping, schedule softreset and abort the link */
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if (unlikely(qc->dev->flags & ATA_DFLAG_SLEEPING)) {
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@ -5935,7 +5935,6 @@ void ata_qc_issue(struct ata_queued_cmd *qc)
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return;
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sg_err:
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qc->flags &= ~ATA_QCFLAG_DMAMAP;
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qc->err_mask |= AC_ERR_SYSTEM;
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err:
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ata_qc_complete(qc);
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