linux-kernel - [PATCH] mmc: dw_mmc: Only inject fault before done/error

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Date:   Wed, 25 Aug 2021 13:42:13 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     Jaehoon Chung <jh80.chung@...sung.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
CC:     <kernel@...s.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] mmc: dw_mmc: Only inject fault before done/error

The fault injection function can set EVENT_DATA_ERROR but skip the
setting of ->data_status to an error status if it hits just after a data
over interrupt.  This confuses the tasklet which can later end up
triggering the WARN_ON(host->cmd || ..) in dw_mci_request_end() since
dw_mci_data_complete() would return success.

Prevent the fault injection function from doing this since this is not a
real case, and ensure that the fault injection doesn't race with a real
error either.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
 drivers/mmc/host/dw_mmc.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 6578cc64ae9e..380f9aa56eb2 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1802,10 +1802,15 @@ static enum hrtimer_restart dw_mci_fault_timer(struct hrtimer *t)
 
 	spin_lock_irqsave(&host->irq_lock, flags);
 
-	if (!host->data_status)
+	/*
+	 * Only inject an error if we haven't already got an error or data over
+	 * interrupt.
+	 */
+	if (!host->data_status) {
 		host->data_status = SDMMC_INT_DCRC;
-	set_bit(EVENT_DATA_ERROR, &host->pending_events);
-	tasklet_schedule(&host->tasklet);
+		set_bit(EVENT_DATA_ERROR, &host->pending_events);
+		tasklet_schedule(&host->tasklet);
+	}
 
 	spin_unlock_irqrestore(&host->irq_lock, flags);
 
@@ -2721,12 +2726,16 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
 		}
 
 		if (pending & DW_MCI_DATA_ERROR_FLAGS) {
+			spin_lock(&host->irq_lock);
+
 			/* if there is an error report DATA_ERROR */
 			mci_writel(host, RINTSTS, DW_MCI_DATA_ERROR_FLAGS);
 			host->data_status = pending;
 			smp_wmb(); /* drain writebuffer */
 			set_bit(EVENT_DATA_ERROR, &host->pending_events);
 			tasklet_schedule(&host->tasklet);
+
+			spin_unlock(&host->irq_lock);
 		}
 
 		if (pending & SDMMC_INT_DATA_OVER) {
-- 
2.28.0