[PATCH] libata: fix qc->n_elem == 0 case handling in ata_qc_next_sg (cc1887f3) · Commits · 戴 / test

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:

Tejun Heo <htejun@gmail.com> Signed-off-by:

Jeff Garzik <jgarzik@pobox.com>

include/linux/libata.h

+14 −2

Original line number	Diff line number	Diff line
		@@ -556,6 +556,16 @@ ata_sg_is_last(struct scatterlist sg, struct ata_queued_cmd qc)
		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 *
		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;
		if (++sg - qc->__sg < qc->n_elem)
		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) \
		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)
		{

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