Commit f92a2636 authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
Browse files

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: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent 001102d7

drivers/ata/libata-core.c

+7 −8
Original line number Diff line number Diff line
@@ -4475,7 +4475,6 @@ void ata_sg_clean(struct ata_queued_cmd *qc) 
	int dir = qc->dma_dir;

	void *pad_buf = NULL;



	WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));

	WARN_ON(sg == NULL);



	VPRINTK("unmapping %u sg elements\n", qc->n_elem);
@@ -4762,11 +4761,9 @@ void ata_noop_qc_prep(struct ata_queued_cmd *qc) { } 
 *	LOCKING:

 *	spin_lock_irqsave(host lock)

 */



void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,

		 unsigned int n_elem)

{

	qc->flags |= ATA_QCFLAG_DMAMAP;

	qc->__sg = sg;

	qc->n_elem = n_elem;

	qc->orig_n_elem = n_elem;
@@ -4795,7 +4792,6 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) 
	int n_elem, pre_n_elem, dir, trim_sg = 0;



	VPRINTK("ENTER, ata%u\n", ap->print_id);

	WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));



	/* we must lengthen transfers to end on a 32-bit boundary */

	qc->pad_len = lsg->length & 3;
@@ -4855,6 +4851,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) 


skip_map:

	qc->n_elem = n_elem;

	qc->flags |= ATA_QCFLAG_DMAMAP;



	return 0;

}
@@ -5912,12 +5909,15 @@ void ata_qc_issue(struct ata_queued_cmd *qc) 
	qc->flags |= ATA_QCFLAG_ACTIVE;

	ap->qc_active |= 1 << qc->tag;



	/* We guarantee to LLDs that they will have at least one

	 * non-zero sg if the command is a data command.

	 */

	BUG_ON(ata_is_data(prot) && (!qc->__sg || !qc->n_elem || !qc->nbytes));



	if (ata_is_dma(prot) || (ata_is_pio(prot) &&

				 (ap->flags & ATA_FLAG_PIO_DMA))) {

				 (ap->flags & ATA_FLAG_PIO_DMA)))

		if (ata_sg_setup(qc))

			goto sg_err;

	} else

		qc->flags &= ATA_QCFLAG_DMAMAP;



	/* if device is sleeping, schedule softreset and abort the link */

	if (unlikely(qc->dev->flags & ATA_DFLAG_SLEEPING)) {
@@ -5935,7 +5935,6 @@ void ata_qc_issue(struct ata_queued_cmd *qc) 
	return;



sg_err:

	qc->flags &= ~ATA_QCFLAG_DMAMAP;

	qc->err_mask |= AC_ERR_SYSTEM;

err:

	ata_qc_complete(qc);

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