mmc: sdhci: Fix SDIO IRQ thread deadlock

Since commit c07a48c2 ("mmc: sdhci: Remove finish_tasklet"), the IRQ
thread might be used to complete requests, but the IRQ thread is also used
to process SDIO card interrupts. This can cause a deadlock when the SDIO
processing tries to access the card since that would also require the IRQ
thread. Change SDHCI to use sdio_signal_irq() to schedule a work item
instead. That also requires implementing the ->ack_sdio_irq() mmc host op.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: c07a48c2 ("mmc: sdhci: Remove finish_tasklet")
Reported-by: Brian Masney <masneyb@onstation.org>
Tested-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -2137,6 +2137,17 @@ void sdhci_enable_sdio_irq(struct mmc_host *mmc, int enable)
 }
 EXPORT_SYMBOL_GPL(sdhci_enable_sdio_irq);
 
+static void sdhci_ack_sdio_irq(struct mmc_host *mmc)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	if (host->flags & SDHCI_SDIO_IRQ_ENABLED)
+		sdhci_enable_sdio_irq_nolock(host, true);
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
 int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
 				      struct mmc_ios *ios)
 {
@@ -2585,6 +2596,7 @@ static const struct mmc_host_ops sdhci_ops = {
 	.get_ro		= sdhci_get_ro,
 	.hw_reset	= sdhci_hw_reset,
 	.enable_sdio_irq = sdhci_enable_sdio_irq,
+	.ack_sdio_irq    = sdhci_ack_sdio_irq,
 	.start_signal_voltage_switch	= sdhci_start_signal_voltage_switch,
 	.prepare_hs400_tuning		= sdhci_prepare_hs400_tuning,
 	.execute_tuning			= sdhci_execute_tuning,
@@ -3087,8 +3099,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
 		if ((intmask & SDHCI_INT_CARD_INT) &&
 		    (host->ier & SDHCI_INT_CARD_INT)) {
 			sdhci_enable_sdio_irq_nolock(host, false);
-			host->thread_isr |= SDHCI_INT_CARD_INT;
-			result = IRQ_WAKE_THREAD;
+			sdio_signal_irq(host->mmc);
 		}
 
 		intmask &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE |
@@ -3160,15 +3171,6 @@ static irqreturn_t sdhci_thread_irq(int irq, void *dev_id)
 		mmc_detect_change(mmc, msecs_to_jiffies(200));
 	}
 
-	if (isr & SDHCI_INT_CARD_INT) {
-		sdio_run_irqs(host->mmc);
-
-		spin_lock_irqsave(&host->lock, flags);
-		if (host->flags & SDHCI_SDIO_IRQ_ENABLED)
-			sdhci_enable_sdio_irq_nolock(host, true);
-		spin_unlock_irqrestore(&host->lock, flags);
-	}
-
 	return IRQ_HANDLED;
 }