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

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Message-ID: <m2r4z28iyn.fsf@bob.laptop.org>
Date:	Sat, 14 Jan 2012 09:19:44 -0500
From:	Chris Ball <cjb@...top.org>
To:	Steven Liu <lingjiujianke@...il.com>
Cc:	linux-mmc@...r.kernel.org, liuqi@...ndersoft.com,
	qinjian@...ndersoft.com, linux-kernel@...r.kernel.org,
	Greg KH <greg@...ah.com>
Subject: Re: [PATCH] mmc: fix deadlock from mmc core when suspend the device

Hi,

On Sat, Jan 14 2012, Steven Liu wrote:
> 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);

Another version of this patch has already gone to Linus, for 3.3-rc1.

Thanks,

- Chris.
-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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