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Commit 3be6cbd7 authored by Jeff Garzik's avatar Jeff Garzik
Browse files

[libata] kill ata_sg_is_last() 



Short term, this works around a bug introduced by early sg-chaining
work.

Long term, removing this function eliminates a branch from a hot
path loop in each scatter/gather table build.  Also, as this code
demonstrates, we don't need to _track_ the end of the s/g list, as
long as we mark it in some way.  And doing so programatically is nice.
So its a useful cleanup, regardless of its short term effects.

Based conceptually on a quick patch by Jens Axboe.

Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 858c9c40

drivers/ata/pdc_adma.c

+6 −3
Original line number Diff line number Diff line
@@ -318,7 +318,7 @@ static int adma_fill_sg(struct ata_queued_cmd *qc) 
	struct scatterlist *sg;

	struct ata_port *ap = qc->ap;

	struct adma_port_priv *pp = ap->private_data;

	u8  *buf = pp->pkt;

	u8  *buf = pp->pkt, *last_buf = NULL;

	int i = (2 + buf[3]) * 8;

	u8 pFLAGS = pORD | ((qc->tf.flags & ATA_TFLAG_WRITE) ? pDIRO : 0);
@@ -334,8 +334,7 @@ static int adma_fill_sg(struct ata_queued_cmd *qc) 
		*(__le32 *)(buf + i) = cpu_to_le32(len);

		i += 4;



		if (ata_sg_is_last(sg, qc))

			pFLAGS |= pEND;

		last_buf = &buf[i];

		buf[i++] = pFLAGS;

		buf[i++] = qc->dev->dma_mode & 0xf;

		buf[i++] = 0;	/* pPKLW */
@@ -348,6 +347,10 @@ static int adma_fill_sg(struct ata_queued_cmd *qc) 
		VPRINTK("PRD[%u] = (0x%lX, 0x%X)\n", i/4,

					(unsigned long)addr, len);

	}



	if (likely(last_buf))

		*last_buf |= pEND;



	return i;

}

drivers/ata/sata_mv.c

+7 −19
Original line number Diff line number Diff line
@@ -421,7 +421,6 @@ static void mv_error_handler(struct ata_port *ap); 
static void mv_post_int_cmd(struct ata_queued_cmd *qc);

static void mv_eh_freeze(struct ata_port *ap);

static void mv_eh_thaw(struct ata_port *ap);

static int mv_slave_config(struct scsi_device *sdev);

static int mv_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);



static void mv5_phy_errata(struct mv_host_priv *hpriv, void __iomem *mmio,
@@ -459,7 +458,7 @@ static struct scsi_host_template mv5_sht = { 
	.use_clustering		= 1,

	.proc_name		= DRV_NAME,

	.dma_boundary		= MV_DMA_BOUNDARY,

	.slave_configure	= mv_slave_config,

	.slave_configure	= ata_scsi_slave_config,

	.slave_destroy		= ata_scsi_slave_destroy,

	.bios_param		= ata_std_bios_param,

};
@@ -477,7 +476,7 @@ static struct scsi_host_template mv6_sht = { 
	.use_clustering		= 1,

	.proc_name		= DRV_NAME,

	.dma_boundary		= MV_DMA_BOUNDARY,

	.slave_configure	= mv_slave_config,

	.slave_configure	= ata_scsi_slave_config,

	.slave_destroy		= ata_scsi_slave_destroy,

	.bios_param		= ata_std_bios_param,

};
@@ -756,17 +755,6 @@ static void mv_irq_clear(struct ata_port *ap) 
{

}



static int mv_slave_config(struct scsi_device *sdev)

{

	int rc = ata_scsi_slave_config(sdev);

	if (rc)

		return rc;



	blk_queue_max_phys_segments(sdev->request_queue, MV_MAX_SG_CT / 2);



	return 0;	/* scsi layer doesn't check return value, sigh */

}



static void mv_set_edma_ptrs(void __iomem *port_mmio,

			     struct mv_host_priv *hpriv,

			     struct mv_port_priv *pp)
@@ -1138,7 +1126,7 @@ static void mv_fill_sg(struct ata_queued_cmd *qc) 
{

	struct mv_port_priv *pp = qc->ap->private_data;

	struct scatterlist *sg;

	struct mv_sg *mv_sg;

	struct mv_sg *mv_sg, *last_sg = NULL;



	mv_sg = pp->sg_tbl;

	ata_for_each_sg(sg, qc) {
@@ -1159,13 +1147,13 @@ static void mv_fill_sg(struct ata_queued_cmd *qc) 
			sg_len -= len;

			addr += len;



			if (!sg_len && ata_sg_is_last(sg, qc))

				mv_sg->flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);



			last_sg = mv_sg;

			mv_sg++;

		}



	}



	if (likely(last_sg))

		last_sg->flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);

}



static inline void mv_crqb_pack_cmd(__le16 *cmdw, u8 data, u8 addr, unsigned last)

drivers/ata/sata_sil24.c

+7 −4
Original line number Diff line number Diff line
@@ -796,16 +796,19 @@ static inline void sil24_fill_sg(struct ata_queued_cmd *qc, 
				 struct sil24_sge *sge)

{

	struct scatterlist *sg;

	struct sil24_sge *last_sge = NULL;



	ata_for_each_sg(sg, qc) {

		sge->addr = cpu_to_le64(sg_dma_address(sg));

		sge->cnt = cpu_to_le32(sg_dma_len(sg));

		if (ata_sg_is_last(sg, qc))

			sge->flags = cpu_to_le32(SGE_TRM);

		else

		sge->flags = 0;



		last_sge = sge;

		sge++;

	}



	if (likely(last_sge))

		last_sge->flags = cpu_to_le32(SGE_TRM);

}



static int sil24_qc_defer(struct ata_queued_cmd *qc)

drivers/scsi/ipr.c

+7 −4
Original line number Diff line number Diff line
@@ -5134,6 +5134,7 @@ static void ipr_build_ata_ioadl(struct ipr_cmnd *ipr_cmd, 
	u32 ioadl_flags = 0;

	struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb;

	struct ipr_ioadl_desc *ioadl = ipr_cmd->ioadl;

	struct ipr_ioadl_desc *last_ioadl = NULL;

	int len = qc->nbytes + qc->pad_len;

	struct scatterlist *sg;
@@ -5156,11 +5157,13 @@ static void ipr_build_ata_ioadl(struct ipr_cmnd *ipr_cmd, 
	ata_for_each_sg(sg, qc) {

		ioadl->flags_and_data_len = cpu_to_be32(ioadl_flags | sg_dma_len(sg));

		ioadl->address = cpu_to_be32(sg_dma_address(sg));

		if (ata_sg_is_last(sg, qc))

			ioadl->flags_and_data_len |= cpu_to_be32(IPR_IOADL_FLAGS_LAST);

		else



		last_ioadl = ioadl;

		ioadl++;

	}



	if (likely(last_ioadl))

		last_ioadl->flags_and_data_len |= cpu_to_be32(IPR_IOADL_FLAGS_LAST);

}



/**

include/linux/libata.h

+0 −12
Original line number Diff line number Diff line
@@ -1037,18 +1037,6 @@ extern void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset, 
/*

 * qc helpers

 */

static inline int

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

{

	if (sg == &qc->pad_sgent)

		return 1;

	if (qc->pad_len)

		return 0;

	if (qc->n_iter == qc->n_elem)

		return 1;

	return 0;

}



static inline struct scatterlist *

ata_qc_first_sg(struct ata_queued_cmd *qc)

{