[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: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 4df8311..7f1b13e 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -421,7 +421,6 @@
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 @@
.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 @@
.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 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 @@
{
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 @@
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)