mmc: fix all hangs related to mmc/sd card insert/removal during suspend/resume

commit 4c2ef25fe0b847d2ae818f74758ddb0be1c27d8e upstream.

If you don't use CONFIG_MMC_UNSAFE_RESUME, as soon as you attempt to
suspend, the card will be removed, therefore this patch doesn't change the
behavior of this option.

However the removal will be done by pm notifier, which runs while
userspace is still not frozen and thus can freely use del_gendisk, without
the risk of deadlock which would happen otherwise.

Card detect workqueue is now disabled while userspace is frozen, Therefore
if you do use CONFIG_MMC_UNSAFE_RESUME, and remove the card during
suspend, the removal will be detected as soon as userspace is unfrozen,
again at the moment it is safe to call del_gendisk.

Tested with and without CONFIG_MMC_UNSAFE_RESUME with suspend and hibernate.

[akpm@linux-foundation.org: clean up function prototype]
[akpm@linux-foundation.org: fix CONFIG_PM-n linkage, small cleanups]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lee Jones <lee.jones@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 57 insertions, 26 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 374a9fc8f312..5de71a5fc29f 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -439,6 +439,17 @@ static int mmc_host_do_disable(struct mmc_host *host, int lazy)
 int mmc_host_disable(struct mmc_host *host)
 {
 	int err;
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	if (host->rescan_disable) {
+		spin_unlock_irqrestore(&host->lock, flags);
+		return;
+	}
+
+	spin_unlock_irqrestore(&host->lock, flags);
+
 
 	if (!(host->caps & MMC_CAP_DISABLE))
 		return 0;
@@ -1309,19 +1320,6 @@ int mmc_suspend_host(struct mmc_host *host)
 	if (host->bus_ops && !host->bus_dead) {
 		if (host->bus_ops->suspend)
 			err = host->bus_ops->suspend(host);
-		if (err == -ENOSYS || !host->bus_ops->resume) {
-			/*
-			 * We simply "remove" the card in this case.
-			 * It will be redetected on resume.
-			 */
-			if (host->bus_ops->remove)
-				host->bus_ops->remove(host);
-			mmc_claim_host(host);
-			mmc_detach_bus(host);
-			mmc_release_host(host);
-			host->pm_flags = 0;
-			err = 0;
-		}
 	}
 	mmc_bus_put(host);
 
@@ -1359,28 +1357,61 @@ int mmc_resume_host(struct mmc_host *host)
 			printk(KERN_WARNING "%s: error %d during resume "
 					    "(card was removed?)\n",
 					    mmc_hostname(host), err);
-			if (host->bus_ops->remove)
-				host->bus_ops->remove(host);
-			mmc_claim_host(host);
-			mmc_detach_bus(host);
-			mmc_release_host(host);
-			/* no need to bother upper layers */
 			err = 0;
 		}
 	}
 	mmc_bus_put(host);
 
-	/*
-	 * We add a slight delay here so that resume can progress
-	 * in parallel.
-	 */
-	mmc_detect_change(host, 1);
-
 	return err;
 }
-
 EXPORT_SYMBOL(mmc_resume_host);
 
+/* Do the card removal on suspend if card is assumed removeable
+ * Do that in pm notifier while userspace isn't yet frozen, so we will be able
+   to sync the card.
+*/
+int mmc_pm_notify(struct notifier_block *notify_block,
+					unsigned long mode, void *unused)
+{
+	struct mmc_host *host = container_of(
+		notify_block, struct mmc_host, pm_notify);
+	unsigned long flags;
+
+
+	switch (mode) {
+	case PM_HIBERNATION_PREPARE:
+	case PM_SUSPEND_PREPARE:
+
+		spin_lock_irqsave(&host->lock, flags);
+		host->rescan_disable = 1;
+		spin_unlock_irqrestore(&host->lock, flags);
+		cancel_delayed_work_sync(&host->detect);
+
+		if (!host->bus_ops || host->bus_ops->suspend)
+			break;
+
+		mmc_claim_host(host);
+
+		if (host->bus_ops->remove)
+			host->bus_ops->remove(host);
+
+		mmc_detach_bus(host);
+		mmc_release_host(host);
+		host->pm_flags = 0;
+		break;
+
+	case PM_POST_SUSPEND:
+	case PM_POST_HIBERNATION:
+
+		spin_lock_irqsave(&host->lock, flags);
+		host->rescan_disable = 0;
+		spin_unlock_irqrestore(&host->lock, flags);
+		mmc_detect_change(host, 0);
+
+	}
+
+	return 0;
+}
 #endif
 
 static int __init mmc_init(void)