Subject: [PATCH] mmc: mmci: Do not release spinlock in request_end

From: [email-masked] (Ulf Hansson)
Date: Fri, 14 Oct 2011 09:37:51 +0200

Jon Medhurst (Tixy) wrote:
> On Thu, 2011-10-13 at 15:29 +0100, Russell King - ARM Linux wrote:
>> On Tue, Oct 11, 2011 at 04:06:41PM +0200, Ulf Hansson wrote:
>>> The patch "mmc: core: move ->request() call from atomic context",
>>> is the reason to why this change is possible. This simplifies the
>>> error handling code execution path quite a lot and potentially also
>>> fixes some error handling hang problems.
>>>
>>> Signed-off-by: Ulf Hansson <[email-masked]>
>> This doesn't look right:
>>
>> void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
>> {
>>         if (err && cmd->retries) {
>>                 host->ops->request(host, mrq);
>>

This is NOT how it looks at mmc-next. You need to test with Adrian 
Hunters patch which the commit refers two.

Linux next for mmc is available at:

git://dev.laptop.org/users/cjb/mmc mmc-next

>> So, not dropping the spinlock results in calling the request function
>> with the spinlock held - and as the request function then goes on to
>> lock the spinlock, we will deadlock.
> 
> Indeed, deadlock behaviour at this point is what I see with this patch
> on a Versatile Express board running 3.0-rc9.
>