mmc: core: Prevent processing SDIO IRQs when the card is suspended

Processing of SDIO IRQs must obviously be prevented while the card is
system suspended, otherwise we may end up trying to communicate with an
uninitialized SDIO card.

Reports throughout the years shows that this is not only a theoretical
problem, but a real issue. So, let's finally fix this problem, by keeping
track of the state for the card and bail out before processing the SDIO
IRQ, in case the card is suspended.

Cc: stable@vger.kernel.org
Reported-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/sdio.c

@@ -937,6 +937,10 @@ static int mmc_sdio_pre_suspend(struct mmc_host *host)
  */
 static int mmc_sdio_suspend(struct mmc_host *host)
 {
+	/* Prevent processing of SDIO IRQs in suspended state. */
+	mmc_card_set_suspended(host->card);
+	cancel_delayed_work_sync(&host->sdio_irq_work);
+
 	mmc_claim_host(host);
 
 	if (mmc_card_keep_power(host) && mmc_card_wake_sdio_irq(host))
@@ -985,13 +989,20 @@ static int mmc_sdio_resume(struct mmc_host *host)
 		err = sdio_enable_4bit_bus(host->card);
 	}
 
-	if (!err && host->sdio_irqs) {
+	if (err)
+		goto out;
+
+	/* Allow SDIO IRQs to be processed again. */
+	mmc_card_clr_suspended(host->card);
+
+	if (host->sdio_irqs) {
 		if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD))
 			wake_up_process(host->sdio_irq_thread);
 		else if (host->caps & MMC_CAP_SDIO_IRQ)
 			host->ops->enable_sdio_irq(host, 1);
 	}
 
+out:
 	mmc_release_host(host);
 
 	host->pm_flags &= ~MMC_PM_KEEP_POWER;

drivers/mmc/core/sdio_irq.c

@@ -34,6 +34,10 @@ static int process_sdio_pending_irqs(struct mmc_host *host)
 	unsigned char pending;
 	struct sdio_func *func;
 
+	/* Don't process SDIO IRQs if the card is suspended. */
+	if (mmc_card_suspended(card))
+		return 0;
+
 	/*
 	 * Optimization, if there is only 1 function interrupt registered
 	 * and we know an IRQ was signaled then call irq handler directly.