From mboxrd@z Thu Jan 1 00:00:00 1970 From: Albert Lee Subject: [PATCH libata-2.6 1/5] Fix zero sg_dma_len() on 64-bit platform Date: Fri, 18 Mar 2005 15:29:17 +0800 Message-ID: <423A834D.5080407@tw.ibm.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------050509070102060504030509" Received: from bluehawaii.tikira.net ([61.62.22.51]:61412 "EHLO bluehawaii.tikira.net") by vger.kernel.org with ESMTP id S261482AbVCRH3z (ORCPT ); Fri, 18 Mar 2005 02:29:55 -0500 Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: Bartlomiej Zolnierkiewicz , Doug Maxey , Linux IDE This is a multi-part message in MIME format. --------------050509070102060504030509 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Hi Jeff, When testing ATAPI PIO data transfer on the ppc64 platform, __atapi_pio_bytes() got zero when sg_dma_len() is used. I checked the , the struct scatterlist is defined as: struct scatterlist { struct page *page; unsigned int offset; unsigned int length; /* For TCE support */ u32 dma_address; u32 dma_length; }; #define sg_dma_address(sg) ((sg)->dma_address) #define sg_dma_len(sg) ((sg)->dma_length) So, if the scatterlist is not DMA mapped, sg_dma_len() will return zero on ppc64. The same problem should occur on the x86-64 platform. On the i386 platform, sg_dma_len() returns sg->length, that's why the problem does not occur on an i386. Changes: - Use sg->length if the scatterlist is not DMA mapped (yet). Attached please find the patch against the libata-2.6 tree for your review. Thanks. Albert Signed-off-by: Albert Lee --------------------------------------- --- libata-2.6/drivers/scsi/libata-core.c 2005-03-17 16:42:32.000000000 +0800 +++ libata-2.6-sgdma/drivers/scsi/libata-core.c 2005-03-17 17:23:42.000000000 +0800 @@ -2071,7 +2071,7 @@ sg = qc->sg; sg->page = virt_to_page(buf); sg->offset = (unsigned long) buf & ~PAGE_MASK; - sg_dma_len(sg) = buflen; + sg->length = buflen; } void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg, @@ -2101,11 +2101,12 @@ dma_addr_t dma_address; dma_address = dma_map_single(ap->host_set->dev, qc->buf_virt, - sg_dma_len(sg), dir); + sg->length, dir); if (dma_mapping_error(dma_address)) return -1; sg_dma_address(sg) = dma_address; + sg_dma_len(sg) = sg->length; DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg), qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read"); @@ -2310,7 +2311,7 @@ qc->cursect++; qc->cursg_ofs++; - if ((qc->cursg_ofs * ATA_SECT_SIZE) == sg_dma_len(&sg[qc->cursg])) { + if ((qc->cursg_ofs * ATA_SECT_SIZE) == (&sg[qc->cursg])->length) { qc->cursg++; qc->cursg_ofs = 0; } @@ -2347,7 +2348,7 @@ page = nth_page(page, (offset >> PAGE_SHIFT)); offset %= PAGE_SIZE; - count = min(sg_dma_len(sg) - qc->cursg_ofs, bytes); + count = min(sg->length - qc->cursg_ofs, bytes); /* don't cross page boundaries */ count = min(count, (unsigned int)PAGE_SIZE - offset); @@ -2358,7 +2359,7 @@ qc->curbytes += count; qc->cursg_ofs += count; - if (qc->cursg_ofs == sg_dma_len(sg)) { + if (qc->cursg_ofs == sg->length) { qc->cursg++; qc->cursg_ofs = 0; } @@ -2371,7 +2372,7 @@ kunmap(page); if (bytes) { - if (qc->cursg_ofs < sg_dma_len(sg)) + if (qc->cursg_ofs < sg->length) goto next_page; goto next_sg; } --------------050509070102060504030509 Content-Type: text/plain; name="sg_dma_len.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="sg_dma_len.diff" --- libata-2.6/drivers/scsi/libata-core.c 2005-03-17 16:42:32.000000000 +0800 +++ libata-2.6-sgdma/drivers/scsi/libata-core.c 2005-03-17 17:23:42.000000000 +0800 @@ -2071,7 +2071,7 @@ sg = qc->sg; sg->page = virt_to_page(buf); sg->offset = (unsigned long) buf & ~PAGE_MASK; - sg_dma_len(sg) = buflen; + sg->length = buflen; } void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg, @@ -2101,11 +2101,12 @@ dma_addr_t dma_address; dma_address = dma_map_single(ap->host_set->dev, qc->buf_virt, - sg_dma_len(sg), dir); + sg->length, dir); if (dma_mapping_error(dma_address)) return -1; sg_dma_address(sg) = dma_address; + sg_dma_len(sg) = sg->length; DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg), qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read"); @@ -2310,7 +2311,7 @@ qc->cursect++; qc->cursg_ofs++; - if ((qc->cursg_ofs * ATA_SECT_SIZE) == sg_dma_len(&sg[qc->cursg])) { + if ((qc->cursg_ofs * ATA_SECT_SIZE) == (&sg[qc->cursg])->length) { qc->cursg++; qc->cursg_ofs = 0; } @@ -2347,7 +2348,7 @@ page = nth_page(page, (offset >> PAGE_SHIFT)); offset %= PAGE_SIZE; - count = min(sg_dma_len(sg) - qc->cursg_ofs, bytes); + count = min(sg->length - qc->cursg_ofs, bytes); /* don't cross page boundaries */ count = min(count, (unsigned int)PAGE_SIZE - offset); @@ -2358,7 +2359,7 @@ qc->curbytes += count; qc->cursg_ofs += count; - if (qc->cursg_ofs == sg_dma_len(sg)) { + if (qc->cursg_ofs == sg->length) { qc->cursg++; qc->cursg_ofs = 0; } @@ -2371,7 +2372,7 @@ kunmap(page); if (bytes) { - if (qc->cursg_ofs < sg_dma_len(sg)) + if (qc->cursg_ofs < sg->length) goto next_page; goto next_sg; } --------------050509070102060504030509--