linux-kernel - [PATCH] MMC: fix hang if card was removed during suspend and unsafe resume was enabled

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Message-Id: <1265325495-4220-1-git-send-email-maximlevitsky@gmail.com>
Date:	Fri,  5 Feb 2010 01:18:15 +0200
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	linux-mmc@...r.kernel.org
Cc:	Philip Langdale <philipl@...rt.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Maxim Levitsky <maximlevitsky@...il.com>
Subject: [PATCH] MMC: fix hang if card was removed during suspend and unsafe resume was enabled

Currently removal of the card leads to del_disk called indirectly by mmc core.
This function expects userspace to be running, which isn't when .resume is called

Fix that by removing the code that did that in mmc_resume_host. It is possible
because card detection logic will kick it later and remove the card.

Also make mtd workqueue freezeable, so it won't attempt to add/remove the card
while userspace is frozen.

Signed-off-by: Maxim Levitsky <maximlevitsky@...il.com>
---
 drivers/mmc/core/core.c |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 30acd52..879d48d 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1257,7 +1257,6 @@ int mmc_suspend_host(struct mmc_host *host, pm_message_t state)
 	if (host->caps & MMC_CAP_DISABLE)
 		cancel_delayed_work(&host->disable);
 	cancel_delayed_work(&host->detect);
-	mmc_flush_scheduled_work();
 
 	mmc_bus_get(host);
 	if (host->bus_ops && !host->bus_dead) {
@@ -1300,15 +1299,11 @@ int mmc_resume_host(struct mmc_host *host)
 		mmc_select_voltage(host, host->ocr);
 		BUG_ON(!host->bus_ops->resume);
 		err = host->bus_ops->resume(host);
+
 		if (err) {
 			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;
 		}
@@ -1332,7 +1327,7 @@ static int __init mmc_init(void)
 {
 	int ret;
 
-	workqueue = create_singlethread_workqueue("kmmcd");
+	workqueue = create_freezeable_workqueue("kmmcd");
 	if (!workqueue)
 		return -ENOMEM;
 
-- 
1.6.3.3

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