From c71ae886d1321e74f524c7c023933cf87768915d Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 18 Jun 2019 09:37:46 +0800 Subject: [PATCH] scsi: ipr: use sg helper to iterate over scatterlist Unlike the legacy I/O path, scsi-mq preallocates a large array to hold the scatterlist for each request. This static allocation can consume substantial amounts of memory on modern controllers which support a large number of concurrently outstanding requests. To facilitate a switch to a smaller static allocation combined with a dynamic allocation for requests that need it, we need to make sure all SCSI drivers handle chained scatterlists correctly. Convert remaining drivers that directly dereference the scatterlist array to using the iterator functions. [mkp: clarified commit message] Reviewed-by: Bart Van Assche Signed-off-by: Ming Lei Signed-off-by: Martin K. Petersen --- drivers/scsi/ipr.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c index 6d053e220153..bf17540affbc 100644 --- a/drivers/scsi/ipr.c +++ b/drivers/scsi/ipr.c @@ -3915,22 +3915,23 @@ static int ipr_copy_ucode_buffer(struct ipr_sglist *sglist, u8 *buffer, u32 len) { int bsize_elem, i, result = 0; - struct scatterlist *scatterlist; + struct scatterlist *sg; void *kaddr; /* Determine the actual number of bytes per element */ bsize_elem = PAGE_SIZE * (1 << sglist->order); - scatterlist = sglist->scatterlist; + sg = sglist->scatterlist; - for (i = 0; i < (len / bsize_elem); i++, buffer += bsize_elem) { - struct page *page = sg_page(&scatterlist[i]); + for (i = 0; i < (len / bsize_elem); i++, sg = sg_next(sg), + buffer += bsize_elem) { + struct page *page = sg_page(sg); kaddr = kmap(page); memcpy(kaddr, buffer, bsize_elem); kunmap(page); - scatterlist[i].length = bsize_elem; + sg->length = bsize_elem; if (result != 0) { ipr_trace; @@ -3939,13 +3940,13 @@ static int ipr_copy_ucode_buffer(struct ipr_sglist *sglist, } if (len % bsize_elem) { - struct page *page = sg_page(&scatterlist[i]); + struct page *page = sg_page(sg); kaddr = kmap(page); memcpy(kaddr, buffer, len % bsize_elem); kunmap(page); - scatterlist[i].length = len % bsize_elem; + sg->length = len % bsize_elem; } sglist->buffer_len = len; @@ -3966,6 +3967,7 @@ static void ipr_build_ucode_ioadl64(struct ipr_cmnd *ipr_cmd, struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb; struct ipr_ioadl64_desc *ioadl64 = ipr_cmd->i.ioadl64; struct scatterlist *scatterlist = sglist->scatterlist; + struct scatterlist *sg; int i; ipr_cmd->dma_use_sg = sglist->num_dma_sg; @@ -3974,10 +3976,10 @@ static void ipr_build_ucode_ioadl64(struct ipr_cmnd *ipr_cmd, ioarcb->ioadl_len = cpu_to_be32(sizeof(struct ipr_ioadl64_desc) * ipr_cmd->dma_use_sg); - for (i = 0; i < ipr_cmd->dma_use_sg; i++) { + for_each_sg(scatterlist, sg, ipr_cmd->dma_use_sg, i) { ioadl64[i].flags = cpu_to_be32(IPR_IOADL_FLAGS_WRITE); - ioadl64[i].data_len = cpu_to_be32(sg_dma_len(&scatterlist[i])); - ioadl64[i].address = cpu_to_be64(sg_dma_address(&scatterlist[i])); + ioadl64[i].data_len = cpu_to_be32(sg_dma_len(sg)); + ioadl64[i].address = cpu_to_be64(sg_dma_address(sg)); } ioadl64[i-1].flags |= cpu_to_be32(IPR_IOADL_FLAGS_LAST); @@ -3997,6 +3999,7 @@ static void ipr_build_ucode_ioadl(struct ipr_cmnd *ipr_cmd, struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb; struct ipr_ioadl_desc *ioadl = ipr_cmd->i.ioadl; struct scatterlist *scatterlist = sglist->scatterlist; + struct scatterlist *sg; int i; ipr_cmd->dma_use_sg = sglist->num_dma_sg; @@ -4006,11 +4009,11 @@ static void ipr_build_ucode_ioadl(struct ipr_cmnd *ipr_cmd, ioarcb->ioadl_len = cpu_to_be32(sizeof(struct ipr_ioadl_desc) * ipr_cmd->dma_use_sg); - for (i = 0; i < ipr_cmd->dma_use_sg; i++) { + for_each_sg(scatterlist, sg, ipr_cmd->dma_use_sg, i) { ioadl[i].flags_and_data_len = - cpu_to_be32(IPR_IOADL_FLAGS_WRITE | sg_dma_len(&scatterlist[i])); + cpu_to_be32(IPR_IOADL_FLAGS_WRITE | sg_dma_len(sg)); ioadl[i].address = - cpu_to_be32(sg_dma_address(&scatterlist[i])); + cpu_to_be32(sg_dma_address(sg)); } ioadl[i-1].flags_and_data_len |=