Commit 49ba0302 authored by Doug Anderson's avatar Doug Anderson Committed by Ulf Hansson
Browse files

mmc: dw_mmc: Add locking around cmd11 timer 



It is possible for the cmd11 interrupt to fire and delete the
cmd11_timer before the cmd11_timer was actually setup.  Let's fix this
race by adding a few spinlocks.  Note that the race wasn't seen in
practice without adding some printk statements, but it still seems
wise to fix.

Fixes: 5c935165 ("mmc: dw_mmc: Add a timeout for sending CMD11")
Signed-off-by: default avatarDoug Anderson <dianders@chromium.org>
Signed-off-by: default avatarJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent fd674198

drivers/mmc/host/dw_mmc.c

+21 −3
Original line number Diff line number Diff line
@@ -1023,14 +1023,23 @@ static void __dw_mci_start_request(struct dw_mci *host, 
	dw_mci_start_command(host, cmd, cmdflags);



	if (cmd->opcode == SD_SWITCH_VOLTAGE) {

		unsigned long irqflags;



		/*

		 * Databook says to fail after 2ms w/ no response, but evidence

		 * shows that sometimes the cmd11 interrupt takes over 130ms.

		 * We'll set to 500ms, plus an extra jiffy just in case jiffies

		 * is just about to roll over.

		 *

		 * We do this whole thing under spinlock and only if the

		 * command hasn't already completed (indicating the the irq

		 * already ran so we don't want the timeout).

		 */

		spin_lock_irqsave(&host->irq_lock, irqflags);

		if (!test_bit(EVENT_CMD_COMPLETE, &host->pending_events))

			mod_timer(&host->cmd11_timer,

				jiffies + msecs_to_jiffies(500) + 1);

		spin_unlock_irqrestore(&host->irq_lock, irqflags);

	}



	if (mrq->stop)
@@ -2160,11 +2169,20 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id) 
		/* Check volt switch first, since it can look like an error */

		if ((host->state == STATE_SENDING_CMD11) &&

		    (pending & SDMMC_INT_VOLT_SWITCH)) {

			del_timer(&host->cmd11_timer);

			unsigned long irqflags;



			mci_writel(host, RINTSTS, SDMMC_INT_VOLT_SWITCH);

			pending &= ~SDMMC_INT_VOLT_SWITCH;



			/*

			 * Hold the lock; we know cmd11_timer can't be kicked

			 * off after the lock is released, so safe to delete.

			 */

			spin_lock_irqsave(&host->irq_lock, irqflags);

			dw_mci_cmd_interrupt(host, pending);

			spin_unlock_irqrestore(&host->irq_lock, irqflags);



			del_timer(&host->cmd11_timer);

		}



		if (pending & DW_MCI_CMD_ERROR_FLAGS) {

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