Re: [PATCH] mmc: core: Fix deadlock when the CONFIG_MMC_UNSAFE_RESUME is not defined

Sujit Reddy Thumma
2011-11-23T03:13:42Z

On 11/22/2011 9:13 PM, Ulf Hansson wrote:
> Sujit Reddy Thumma wrote:
>> mmc_suspend_host() tries to claim host during suspend
>> and release it only when the bus suspend operation is
>> compeleted. If CONFIG_MMC_UNSAFE_RESUME is defined and
>> the host is flagged as removable, mmc_suspend_host()
>> tries to remove the card. In this process, the file system
>> sync can get blocked trying to acquire host which is already
>> claimed by mmc_suspend_host() causing deadlock.
>>
>> Fix this deadlock by releasing host before ->remove() is called.
>>
>> Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
>> ---
>> drivers/mmc/core/core.c | 4 +++-
>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 271efea..8adbadf 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -2338,6 +2338,7 @@ int mmc_suspend_host(struct mmc_host *host)
>> * We simply "remove" the card in this case.
>> * It will be redetected on resume.
>> */
>> + mmc_do_release_host(host);
>
> Instead of having an "else" below move mmc_do_release_host to be done
> before "if (err == -ENOSYS || !host->bus_ops->resume)"

Sure.

>
>> if (host->bus_ops->remove)
>> host->bus_ops->remove(host);
>> mmc_claim_host(host);
>> @@ -2346,8 +2347,9 @@ int mmc_suspend_host(struct mmc_host *host)
>> mmc_release_host(host);
>> host->pm_flags = 0;
>> err = 0;
>> + } else {
>> + mmc_do_release_host(host);
>> }
>
> Remove else statement entirely.

Okay. Will do it.

Thanks,
Sujit