netdev - [PATCH 17/22] mmc: sdhci: Make use of the new sg

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Date:   Thu, 13 Apr 2017 16:05:30 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Christoph Hellwig <hch@....de>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sagi Grimberg <sagi@...mberg.me>, Jens Axboe <axboe@...nel.dk>,
        Tejun Heo <tj@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Ming Lin <ming.l@....samsung.com>,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, intel-gfx@...ts.freedesktop.org,
        linux-raid@...r.kernel.org, linux-mmc@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-nvdimm@...ts.01.org,
        linux-scsi@...r.kernel.org, fcoe-devel@...n-fcoe.org,
        open-iscsi@...glegroups.com, megaraidlinux.pdl@...adcom.com,
        sparmaintainer@...sys.com, devel@...verdev.osuosl.org,
        target-devel@...r.kernel.org, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, rds-devel@....oracle.com
Cc:     Steve Wise <swise@...ngridcomputing.com>,
        Stephen Bates <sbates@...thlin.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH 17/22] mmc: sdhci: Make use of the new sg_map helper function

Straightforward conversion, except due to the lack of error path we
have to WARN if the memory in the SGL is not mappable.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 drivers/mmc/host/sdhci.c | 35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 63bc33a..af0c107 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -497,15 +497,34 @@ static int sdhci_pre_dma_transfer(struct sdhci_host *host,
 	return sg_count;
 }
 
+/*
+ * Note this function may return PTR_ERR and must be checked.
+ */
 static char *sdhci_kmap_atomic(struct scatterlist *sg, unsigned long *flags)
 {
+	void *ret;
+
 	local_irq_save(*flags);
-	return kmap_atomic(sg_page(sg)) + sg->offset;
+
+	ret = sg_map(sg, SG_KMAP_ATOMIC);
+	if (IS_ERR(ret)) {
+		/*
+		 * This should really never happen unless the code is changed
+		 * to use memory that is not mappable in the sg. Seeing there
+		 * doesn't seem to be any error path out of here, we can only
+		 * WARN.
+		 */
+		WARN(1, "Non-mappable memory used in sg!");
+		local_irq_restore(*flags);
+	}
+
+	return ret;
 }
 
-static void sdhci_kunmap_atomic(void *buffer, unsigned long *flags)
+static void sdhci_kunmap_atomic(struct scatterlist *sg, void *buffer,
+				unsigned long *flags)
 {
-	kunmap_atomic(buffer);
+	sg_unmap(sg, buffer, SG_KMAP_ATOMIC);
 	local_irq_restore(*flags);
 }
 
@@ -568,8 +587,11 @@ static void sdhci_adma_table_pre(struct sdhci_host *host,
 		if (offset) {
 			if (data->flags & MMC_DATA_WRITE) {
 				buffer = sdhci_kmap_atomic(sg, &flags);
+				if (IS_ERR(buffer))
+					return;
+
 				memcpy(align, buffer, offset);
-				sdhci_kunmap_atomic(buffer, &flags);
+				sdhci_kunmap_atomic(sg, buffer, &flags);
 			}
 
 			/* tran, valid */
@@ -646,8 +668,11 @@ static void sdhci_adma_table_post(struct sdhci_host *host,
 					       (sg_dma_address(sg) & SDHCI_ADMA2_MASK);
 
 					buffer = sdhci_kmap_atomic(sg, &flags);
+					if (IS_ERR(buffer))
+						return;
+
 					memcpy(buffer, align, size);
-					sdhci_kunmap_atomic(buffer, &flags);
+					sdhci_kunmap_atomic(sg, buffer, &flags);
 
 					align += SDHCI_ADMA2_ALIGN;
 				}
-- 
2.1.4