mmc: core: fix __mmc_switch timeout caused by preempt

ChaotianJing · storulf · commit 3bbb0deea6d5 · 2015-12-22T11:32:18.000+01:00
there is a time window between __mmc_send_status() and time_afer(),
on some eMMC chip, the timeout_ms is only 10ms, if this thread was
scheduled out during this period, then, even card has already changes
to transfer state by the result of CMD13, this part of code also treat
it to timeout error.
So, need calculate timeout first, then call __mmc_send_status(), if
already timeout and card still in programing state, then treat it to
the real timeout error.

Signed-off-by: Chaotian Jing &lt;chaotian.jing@mediatek.com&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
@@ -489,6 +489,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 	unsigned long timeout;
 	u32 status = 0;
 	bool use_r1b_resp = use_busy_signal;
+	bool expired = false;
 
 	mmc_retune_hold(host);
 
@@ -545,6 +546,12 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 	timeout = jiffies + msecs_to_jiffies(timeout_ms);
 	do {
 		if (send_status) {
+			/*
+			 * Due to the possibility of being preempted after
+			 * sending the status command, check the expiration
+			 * time first.
+			 */
+			expired = time_after(jiffies, timeout);
 			err = __mmc_send_status(card, &status, ignore_crc);
 			if (err)
 				goto out;
@@ -565,7 +572,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 		}
 
 		/* Timeout if the device never leaves the program state. */
-		if (time_after(jiffies, timeout)) {
+		if (expired && R1_CURRENT_STATE(status) == R1_STATE_PRG) {
 			pr_err("%s: Card stuck in programming state! %s\n",
 				mmc_hostname(host), __func__);
 			err = -ETIMEDOUT;
