linux-kernel - [PATCH] mmc: fix deadlock from mmc core when suspend the device

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Date:	Sat, 14 Jan 2012 13:05:08 +0800
From:	Steven Liu <lingjiujianke@...il.com>
To:	cjb@...top.org, linux-mmc@...r.kernel.org, liuqi@...ndersoft.com,
	qinjian@...ndersoft.com
Cc:	linux-kernel@...r.kernel.org, Greg KH <greg@...ah.com>
Subject: [PATCH] mmc: fix deadlock from mmc core when suspend the device

Hi Chris Ball & Greg KH,

This patch can fix the mmc deadlock when suspen the mmc devices.

when mmc_pm_notify to do the host->bus_ops->remove, there is deadlock,
because it was locked at mmc_claim_host, so it modify the mmc_claim_host
after the host->bus_ops->remove.
the problem can reproduce at lots of the emmc/sd devices when create
multi partitions,and I have tested this modify at lots of the platform.

Can this patch fixed?

Signed-off-by: LiuQi <liuqi@...ndersoft.com>
Signed-off-by: Jack Qin <qinjian@...ndersoft.com>

---
 drivers/mmc/core/core.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 950b97d..e68a0e8 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2431,11 +2431,10 @@ int mmc_pm_notify(struct notifier_block *notify_block,
                if (!host->bus_ops || host->bus_ops->suspend)
                        break;

-               mmc_claim_host(host);
-
                if (host->bus_ops->remove)
                        host->bus_ops->remove(host);

+               mmc_claim_host(host);
                mmc_detach_bus(host);
                mmc_power_off(host);
                mmc_release_host(host);
--
1.7.7




Thanks
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