mmc: sdhci: fix dma memory leak in sdhci_pre_req()

Currently one mrq->data maybe execute dma_map_sg() twice
when mmc subsystem prepare over one new request, and the
following log show up:
	sdhci[sdhci_pre_dma_transfer] invalid cookie: 24, next-cookie 25

In this condition, mrq->date map a dma-memory(1) in sdhci_pre_req
for the first time, and map another dma-memory(2) in sdhci_prepare_data
for the second time. But driver only unmap the dma-memory(2), and
dma-memory(1) never unmapped, which cause the dma memory leak issue.

This patch use another method to map the dma memory for the mrq->data
which can fix this dma memory leak issue.

Fixes: 348487cb28e6 ("mmc: sdhci: use pipeline mmc requests to improve performance")
Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Haibo Chen <haibo.chen@freescale.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -54,8 +54,7 @@ static void sdhci_finish_command(struct sdhci_host *);
 static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode);
 static void sdhci_enable_preset_value(struct sdhci_host *host, bool enable);
 static int sdhci_pre_dma_transfer(struct sdhci_host *host,
-					struct mmc_data *data,
-					struct sdhci_host_next *next);
+					struct mmc_data *data);
 static int sdhci_do_get_cd(struct sdhci_host *host);
 
 #ifdef CONFIG_PM
@@ -495,7 +494,7 @@ static int sdhci_adma_table_pre(struct sdhci_host *host,
 		goto fail;
 	BUG_ON(host->align_addr & host->align_mask);
 
-	host->sg_count = sdhci_pre_dma_transfer(host, data, NULL);
+	host->sg_count = sdhci_pre_dma_transfer(host, data);
 	if (host->sg_count < 0)
 		goto unmap_align;
 
@@ -634,9 +633,11 @@ static void sdhci_adma_table_post(struct sdhci_host *host,
 		}
 	}
 
-	if (!data->host_cookie)
+	if (data->host_cookie == COOKIE_MAPPED) {
 		dma_unmap_sg(mmc_dev(host->mmc), data->sg,
 			data->sg_len, direction);
+		data->host_cookie = COOKIE_UNMAPPED;
+	}
 }
 
 static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
@@ -832,7 +833,7 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
 		} else {
 			int sg_cnt;
 
-			sg_cnt = sdhci_pre_dma_transfer(host, data, NULL);
+			sg_cnt = sdhci_pre_dma_transfer(host, data);
 			if (sg_cnt <= 0) {
 				/*
 				 * This only happens when someone fed
@@ -948,11 +949,13 @@ static void sdhci_finish_data(struct sdhci_host *host)
 		if (host->flags & SDHCI_USE_ADMA)
 			sdhci_adma_table_post(host, data);
 		else {
-			if (!data->host_cookie)
+			if (data->host_cookie == COOKIE_MAPPED) {
 				dma_unmap_sg(mmc_dev(host->mmc),
 					data->sg, data->sg_len,
 					(data->flags & MMC_DATA_READ) ?
 					DMA_FROM_DEVICE : DMA_TO_DEVICE);
+				data->host_cookie = COOKIE_UNMAPPED;
+			}
 		}
 	}
 
@@ -2116,49 +2119,36 @@ static void sdhci_post_req(struct mmc_host *mmc, struct mmc_request *mrq,
 	struct mmc_data *data = mrq->data;
 
 	if (host->flags & SDHCI_REQ_USE_DMA) {
-		if (data->host_cookie)
+		if (data->host_cookie == COOKIE_GIVEN ||
+				data->host_cookie == COOKIE_MAPPED)
 			dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
 					 data->flags & MMC_DATA_WRITE ?
 					 DMA_TO_DEVICE : DMA_FROM_DEVICE);
-		mrq->data->host_cookie = 0;
+		data->host_cookie = COOKIE_UNMAPPED;
 	}
 }
 
 static int sdhci_pre_dma_transfer(struct sdhci_host *host,
-				       struct mmc_data *data,
-				       struct sdhci_host_next *next)
+				       struct mmc_data *data)
 {
 	int sg_count;
 
-	if (!next && data->host_cookie &&
-	    data->host_cookie != host->next_data.cookie) {
-		pr_debug(DRIVER_NAME "[%s] invalid cookie: %d, next-cookie %d\n",
-			__func__, data->host_cookie, host->next_data.cookie);
-		data->host_cookie = 0;
+	if (data->host_cookie == COOKIE_MAPPED) {
+		data->host_cookie = COOKIE_GIVEN;
+		return data->sg_count;
 	}
 
-	/* Check if next job is already prepared */
-	if (next ||
-	    (!next && data->host_cookie != host->next_data.cookie)) {
-		sg_count = dma_map_sg(mmc_dev(host->mmc), data->sg,
-				     data->sg_len,
-				     data->flags & MMC_DATA_WRITE ?
-				     DMA_TO_DEVICE : DMA_FROM_DEVICE);
-
-	} else {
-		sg_count = host->next_data.sg_count;
-		host->next_data.sg_count = 0;
-	}
+	WARN_ON(data->host_cookie == COOKIE_GIVEN);
 
+	sg_count = dma_map_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
+				data->flags & MMC_DATA_WRITE ?
+				DMA_TO_DEVICE : DMA_FROM_DEVICE);
 
 	if (sg_count == 0)
-		return -EINVAL;
+		return -ENOSPC;
 
-	if (next) {
-		next->sg_count = sg_count;
-		data->host_cookie = ++next->cookie < 0 ? 1 : next->cookie;
-	} else
-		host->sg_count = sg_count;
+	data->sg_count = sg_count;
+	data->host_cookie = COOKIE_MAPPED;
 
 	return sg_count;
 }
@@ -2168,16 +2158,10 @@ static void sdhci_pre_req(struct mmc_host *mmc, struct mmc_request *mrq,
 {
 	struct sdhci_host *host = mmc_priv(mmc);
 
-	if (mrq->data->host_cookie) {
-		mrq->data->host_cookie = 0;
-		return;
-	}
+	mrq->data->host_cookie = COOKIE_UNMAPPED;
 
 	if (host->flags & SDHCI_REQ_USE_DMA)
-		if (sdhci_pre_dma_transfer(host,
-					mrq->data,
-					&host->next_data) < 0)
-			mrq->data->host_cookie = 0;
+		sdhci_pre_dma_transfer(host, mrq->data);
 }
 
 static void sdhci_card_event(struct mmc_host *mmc)
@@ -3049,7 +3033,6 @@ int sdhci_add_host(struct sdhci_host *host)
 		host->max_clk = host->ops->get_max_clock(host);
 	}
 
-	host->next_data.cookie = 1;
 	/*
 	 * In case of Host Controller v3.00, find out whether clock
 	 * multiplier is supported.

drivers/mmc/host/sdhci.h

@@ -309,9 +309,10 @@ struct sdhci_adma2_64_desc {
  */
 #define SDHCI_MAX_SEGS		128
 
-struct sdhci_host_next {
-	unsigned int	sg_count;
-	s32		cookie;
+enum sdhci_cookie {
+	COOKIE_UNMAPPED,
+	COOKIE_MAPPED,
+	COOKIE_GIVEN,
 };
 
 struct sdhci_host {
@@ -505,7 +506,6 @@ struct sdhci_host {
 	unsigned int		tuning_mode;	/* Re-tuning mode supported by host */
 #define SDHCI_TUNING_MODE_1	0
 
-	struct sdhci_host_next	next_data;
 	unsigned long private[0] ____cacheline_aligned;
 };