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>

5 files changed, 89 insertions, 52 deletions

diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig
index 10ba9a035a58..325f3402e252 100644
--- a/drivers/mmc/card/Kconfig
+++ b/drivers/mmc/card/Kconfig
@@ -32,6 +32,15 @@ config MMC_BLOCK_BOUNCE
 
 	  If unsure, say Y here.
 
+config MMC_BLOCK_DEFERRED_RESUME
+	bool "Deferr MMC layer resume until I/O is requested"
+	depends on MMC_BLOCK
+	default n
+	help
+	  Say Y here to enable deferred MMC resume until I/O
+	  is requested. This will reduce overall resume latency and
+	  save power when theres an SD card inserted but not being used.
+
 config SDIO_UART
 	tristate "SDIO UART/GPS class support"
 	help
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index a1239b93c078..e50fc26baa4e 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -268,6 +268,7 @@ mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
 	return 0;
 }
 
+
 static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 {
 	struct mmc_blk_data *md = mq->data;
@@ -275,6 +276,13 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 	struct mmc_blk_request brq;
 	int ret = 1, disable_multi = 0;
 
+#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
+	if (mmc_bus_needs_resume(card->host)) {
+		mmc_resume_bus(card->host);
+		mmc_blk_set_blksize(md, card);
+	}
+#endif
+
 	mmc_claim_host(card->host);
 
 	do {
@@ -589,32 +597,6 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
 	return ERR_PTR(ret);
 }
 
-static int
-mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
-{
-	struct mmc_command cmd;
-	int err;
-
-	/* Block-addressed cards ignore MMC_SET_BLOCKLEN. */
-	if (mmc_card_blockaddr(card))
-		return 0;
-
-	mmc_claim_host(card->host);
-	cmd.opcode = MMC_SET_BLOCKLEN;
-	cmd.arg = 512;
-	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
-	err = mmc_wait_for_cmd(card->host, &cmd, 5);
-	mmc_release_host(card->host);
-
-	if (err) {
-		printk(KERN_ERR "%s: unable to set block size to %d: %d\n",
-			md->disk->disk_name, cmd.arg, err);
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 static int mmc_blk_probe(struct mmc_card *card)
 {
 	struct mmc_blk_data *md;
@@ -643,6 +625,9 @@ static int mmc_blk_probe(struct mmc_card *card)
 		cap_str, md->read_only ? "(ro)" : "");
 
 	mmc_set_drvdata(card, md);
+#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
+	mmc_set_bus_resume_policy(card->host, 1);
+#endif
 	add_disk(md->disk);
 	return 0;
 
@@ -667,6 +652,9 @@ static void mmc_blk_remove(struct mmc_card *card)
 		mmc_blk_put(md);
 	}
 	mmc_set_drvdata(card, NULL);
+#ifdef CONFIG_MMC_BLOCK_DEFERRED_RESUME
+	mmc_set_bus_resume_policy(card->host, 0);
+#endif
 }
 
 #ifdef CONFIG_PM
@@ -685,7 +673,9 @@ static int mmc_blk_resume(struct mmc_card *card)
 	struct mmc_blk_data *md = mmc_get_drvdata(card);
 
 	if (md) {
+#ifndef CONFIG_MMC_BLOCK_DEFERRED_RESUME
 		mmc_blk_set_blksize(md, card);
+#endif
 		mmc_queue_resume(&md->queue);
 	}
 	return 0;
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)
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 47353909e345..0efe631e50ca 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -17,6 +17,7 @@
 #include <linux/pagemap.h>
 #include <linux/leds.h>
 #include <linux/slab.h>
+#include <linux/suspend.h>
 
 #include <linux/mmc/host.h>
 
@@ -85,6 +86,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 	init_waitqueue_head(&host->wq);
 	INIT_DELAYED_WORK(&host->detect, mmc_rescan);
 	INIT_DELAYED_WORK_DEFERRABLE(&host->disable, mmc_host_deeper_disable);
+	host->pm_notify.notifier_call = mmc_pm_notify;
 
 	/*
 	 * By default, hosts do not support SGIO or large requests.
@@ -133,6 +135,7 @@ int mmc_add_host(struct mmc_host *host)
 #endif
 
 	mmc_start_host(host);
+	register_pm_notifier(&host->pm_notify);
 
 	return 0;
 }
@@ -149,6 +152,7 @@ EXPORT_SYMBOL(mmc_add_host);
  */
 void mmc_remove_host(struct mmc_host *host)
 {
+	unregister_pm_notifier(&host->pm_notify);
 	mmc_stop_host(host);
 
 #ifdef CONFIG_DEBUG_FS
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index ddd7adef8a08..d427ef04d882 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -125,6 +125,7 @@ struct mmc_host {
 	unsigned int		f_min;
 	unsigned int		f_max;
 	u32			ocr_avail;
+	struct notifier_block	pm_notify;
 
 #define MMC_VDD_165_195		0x00000080	/* VDD voltage 1.65 - 1.95 */
 #define MMC_VDD_20_21		0x00000100	/* VDD voltage 2.0 ~ 2.1 */
@@ -185,6 +186,7 @@ struct mmc_host {
 
 	/* Only used with MMC_CAP_DISABLE */
 	int			enabled;	/* host is enabled */
+	int			rescan_disable;	/* disable card detection */
 	int			nesting_cnt;	/* "enable" nesting count */
 	int			en_dis_recurs;	/* detect recursion */
 	unsigned int		disable_delay;	/* disable delay in msecs */
@@ -274,6 +276,7 @@ int mmc_card_can_sleep(struct mmc_host *host);
 int mmc_host_enable(struct mmc_host *host);
 int mmc_host_disable(struct mmc_host *host);
 int mmc_host_lazy_disable(struct mmc_host *host);
+int mmc_pm_notify(struct notifier_block *notify_block, unsigned long, void *);
 
 static inline void mmc_set_disable_delay(struct mmc_host *host,
 					 unsigned int disable_delay)