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

Jon Medhurst (Tixy) jon.medhurst at linaro.org
Thu Oct 13 11:59:52 EDT 2011


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 <ulf.hansson at stericsson.com>
> 
> 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);
> 
> 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.

-- 
Tixy




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