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Commit cc1887f3 authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
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[PATCH] libata: fix qc->n_elem == 0 case handling in ata_qc_next_sg 



This patch makes ata_for_each_sg() start with pad_sgent when
qc->n_elem is zero.  Previously, ata_for_each_sg() unconditionally
started with qc->__sg, handling the first sg to fill_sg() routines
even when the entry was invalid.  And while at it, unwind ?: in
ata_qc_next_sg() into if statement.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent 9ae61c6c

include/linux/libata.h

+14 −2
Original line number Original line Diff line number Diff line
@@ -556,6 +556,16 @@ ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc) 
	return 0;

	return 0;

}

}





static inline struct scatterlist *

ata_qc_first_sg(struct ata_queued_cmd *qc)

{

	if (qc->n_elem)

		return qc->__sg;

	if (qc->pad_len)

		return &qc->pad_sgent;

	return NULL;

}



static inline struct scatterlist *

static inline struct scatterlist *

ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc)

ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc)

{

{
@@ -563,11 +573,13 @@ ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc) 
		return NULL;

		return NULL;

	if (++sg - qc->__sg < qc->n_elem)

	if (++sg - qc->__sg < qc->n_elem)

		return sg;

		return sg;

	return qc->pad_len ? &qc->pad_sgent : NULL;

	if (qc->pad_len)

		return &qc->pad_sgent;

	return NULL;

}

}





#define ata_for_each_sg(sg, qc) \

#define ata_for_each_sg(sg, qc) \

	for (sg = qc->__sg; sg; sg = ata_qc_next_sg(sg, qc))

	for (sg = ata_qc_first_sg(qc); sg; sg = ata_qc_next_sg(sg, qc))





static inline unsigned int ata_tag_valid(unsigned int tag)

static inline unsigned int ata_tag_valid(unsigned int tag)

{

{