[PATCH] mmc: core: Check for timeout before checking mmc device state

[Matt Bennett]

On a system that has multiple devices on the mmc bus the host can
block on the mutex that protects access to the bus. Some operations
require the status of the device to be polled to see when the device
finishes executing the previous command that was sent to it (if
there is no busy detection in hardware). The current execution order
to check the status is:

LOOP
{
  1. Send command to device to retrieve the status (this can block).
  2. Check we haven't exceeded the timeout value. If we have then
     return an error.
  3. If the device is no longer in the program state then exit the
     loop and continue through the function.
}

If the send command blocks (and the timeout is exceeded) then the
function returns (and prints) an error even though the device has
likely left the programming state (due to the lengthy period of
time while the bus is blocked). By moving the timeout check before
retrieving the device status in the loop we better handle the case
where the mmc bus has been blocked but the device has left the
programming state.

Signed-off-by: Matt Bennett <matt.bennett@xxxxxxxxxxxxxxxxxxx>
Cc: kuninori.morimoto.gx@xxxxxxxxxxx
Cc: jh80.chung@xxxxxxxxxxx
Cc: sboyd@xxxxxxxxxxxxxx
Cc: johan.rudholm@xxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mmc@xxxxxxxxxxxxxxx
---
 drivers/mmc/card/block.c   | 22 +++++++++++-----------
 drivers/mmc/core/core.c    | 20 ++++++++++----------
 drivers/mmc/core/mmc_ops.c | 14 +++++++-------
 3 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 2c25271..0abefde 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -747,6 +747,17 @@ static int card_busy_detect(struct mmc_card *card, unsigned int timeout_ms,
 	u32 status;
 
 	do {
+		/*
+		 * Timeout if the device never becomes ready for data and never
+		 * leaves the program state.
+		 */
+		if (time_after(jiffies, timeout)) {
+			pr_err("%s: Card stuck in programming state! %s %s\n",
+				mmc_hostname(card->host),
+				req->rq_disk->disk_name, __func__);
+			return -ETIMEDOUT;
+		}
+
 		err = get_card_status(card, &status, 5);
 		if (err) {
 			pr_err("%s: error %d requesting status\n",
@@ -766,17 +777,6 @@ static int card_busy_detect(struct mmc_card *card, unsigned int timeout_ms,
 			break;
 
 		/*
-		 * Timeout if the device never becomes ready for data and never
-		 * leaves the program state.
-		 */
-		if (time_after(jiffies, timeout)) {
-			pr_err("%s: Card stuck in programming state! %s %s\n",
-				mmc_hostname(card->host),
-				req->rq_disk->disk_name, __func__);
-			return -ETIMEDOUT;
-		}
-
-		/*
 		 * Some cards mishandle the status bits,
 		 * so make sure to check both the busy
 		 * indication and the card state.
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index c296bc0..6e56cb3 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2047,6 +2047,16 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
 
 	timeout = jiffies + msecs_to_jiffies(MMC_CORE_TIMEOUT_MS);
 	do {
+		/* Timeout if the device never becomes ready for data and
+		 * never leaves the program state.
+		 */
+		if (time_after(jiffies, timeout)) {
+			pr_err("%s: Card stuck in programming state! %s\n",
+				mmc_hostname(card->host), __func__);
+			err =  -EIO;
+			goto out;
+		}
+
 		memset(&cmd, 0, sizeof(struct mmc_command));
 		cmd.opcode = MMC_SEND_STATUS;
 		cmd.arg = card->rca << 16;
@@ -2060,16 +2070,6 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
 			goto out;
 		}
 
-		/* Timeout if the device never becomes ready for data and
-		 * never leaves the program state.
-		 */
-		if (time_after(jiffies, timeout)) {
-			pr_err("%s: Card stuck in programming state! %s\n",
-				mmc_hostname(card->host), __func__);
-			err =  -EIO;
-			goto out;
-		}
-
 	} while (!(cmd.resp[0] & R1_READY_FOR_DATA) ||
 		 (R1_CURRENT_STATE(cmd.resp[0]) == R1_STATE_PRG));
 out:
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 0ea042d..b30ed91 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -526,6 +526,13 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 	/* Must check status to be sure of no errors. */
 	timeout = jiffies + msecs_to_jiffies(timeout_ms);
 	do {
+		/* Timeout if the device never leaves the program state. */
+		if (time_after(jiffies, timeout)) {
+			pr_err("%s: Card stuck in programming state! %s\n",
+				mmc_hostname(host), __func__);
+			return -ETIMEDOUT;
+		}
+
 		if (send_status) {
 			err = __mmc_send_status(card, &status, ignore_crc);
 			if (err)
@@ -545,13 +552,6 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 			mmc_delay(timeout_ms);
 			return 0;
 		}
-
-		/* Timeout if the device never leaves the program state. */
-		if (time_after(jiffies, timeout)) {
-			pr_err("%s: Card stuck in programming state! %s\n",
-				mmc_hostname(host), __func__);
-			return -ETIMEDOUT;
-		}
 	} while (R1_CURRENT_STATE(status) == R1_STATE_PRG);
 
 	if (mmc_host_is_spi(host)) {
-- 
1.9.1

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