From 3be6cbd73f74b4a3da82cc7d6e1688a4ae595fc7 Mon Sep 17 00:00:00 2001 From: Jeff Garzik Date: Thu, 18 Oct 2007 16:21:18 -0400 Subject: [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 --- drivers/scsi/ipr.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'drivers/scsi/ipr.c') diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c index b41dfb539021..c316a0bcae6c 100644 --- a/drivers/scsi/ipr.c +++ b/drivers/scsi/ipr.c @@ -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 - ioadl++; + + last_ioadl = ioadl; + ioadl++; } + + if (likely(last_ioadl)) + last_ioadl->flags_and_data_len |= cpu_to_be32(IPR_IOADL_FLAGS_LAST); } /** -- cgit v1.2.1