[PATCH V7 13/25] mmc: core: Do not prepare a new request twice

[Adrian Hunter <adrian.hunter@intel.com>]

mmc_start_req() assumes it is never called with the new request already
prepared. That is true if the queue consists of only 2 requests, but is not
true for a longer queue. e.g. mmc_start_req() has a current and previous
request but still exits to queue a new request if the queue size is
greater than 2. In that case, when mmc_start_req() is called again, the
current request will have been prepared already. Fix by flagging if the
request has been prepared.

That also means ensuring that struct mmc_async_req is always initialized
to zero, which wasn't the case in mmc_test.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/mmc/card/mmc_test.c |  8 ++++----
 drivers/mmc/core/core.c     | 12 +++++++++---
 include/linux/mmc/host.h    |  1 +
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/card/mmc_test.c b/drivers/mmc/card/mmc_test.c
index b42c23665104..81a71d28239a 100644
--- a/drivers/mmc/card/mmc_test.c
+++ b/drivers/mmc/card/mmc_test.c
@@ -826,7 +826,10 @@ static int mmc_test_nonblock_transfer(struct mmc_test_card *test,
 	struct mmc_command stop2;
 	struct mmc_data data2;
 
-	struct mmc_test_async_req test_areq[2];
+	struct mmc_test_async_req test_areq[2] = {
+		{ .test = test },
+		{ .test = test },
+	};
 	struct mmc_async_req *done_areq;
 	struct mmc_async_req *cur_areq = &test_areq[0].areq;
 	struct mmc_async_req *other_areq = &test_areq[1].areq;
@@ -834,9 +837,6 @@ static int mmc_test_nonblock_transfer(struct mmc_test_card *test,
 	int i;
 	int ret = RESULT_OK;
 
-	test_areq[0].test = test;
-	test_areq[1].test = test;
-
 	mmc_test_nonblock_reset(&mrq1, &cmd1, &stop1, &data1);
 	mmc_test_nonblock_reset(&mrq2, &cmd2, &stop2, &data2);
 
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index dc1f27ee50b8..28e1495ac903 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -658,8 +658,10 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
 	struct mmc_async_req *data = host->areq;
 
 	/* Prepare a new request */
-	if (areq)
+	if (areq && !areq->pre_req_done) {
+		areq->pre_req_done = true;
 		mmc_pre_req(host, areq->mrq);
+	}
 
 	if (host->areq) {
 		status = mmc_wait_for_data_req_done(host, host->areq->mrq, areq);
@@ -695,12 +697,16 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
 	if (status == MMC_BLK_SUCCESS && areq)
 		start_err = __mmc_start_data_req(host, areq->mrq);
 
-	if (host->areq)
+	if (host->areq) {
+		host->areq->pre_req_done = false;
 		mmc_post_req(host, host->areq->mrq, 0);
+	}
 
 	 /* Cancel a prepared request if it was not started. */
-	if ((status != MMC_BLK_SUCCESS || start_err) && areq)
+	if ((status != MMC_BLK_SUCCESS || start_err) && areq) {
+		areq->pre_req_done = false;
 		mmc_post_req(host, areq->mrq, -EINVAL);
+	}
 
 	if (status != MMC_BLK_SUCCESS)
 		host->areq = NULL;
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index bcf6d252ec67..fa44aa93505a 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -173,6 +173,7 @@ struct mmc_async_req {
 	 * Returns 0 if success otherwise non zero.
 	 */
 	enum mmc_blk_status (*err_check)(struct mmc_card *, struct mmc_async_req *);
+	bool pre_req_done;
 };
 
 /**
-- 
1.9.1