Re: [PATCH 2/4] mmc: core: allow non-blocking form of mmc_claim_host

Ulf Hansson
2015-03-23T09:58:27Z

On 24 February 2015 at 03:42, NeilBrown <neilb@suse.de> wrote:
> Change the handling for the 'abort' flag so that if
> it is set, but we can claim the host, then do the claim,
> rather than aborting.
>
> When the abort is async this just means that a race between aborting
> an allowing a claim is resolved slightly differently. Any
> code must already be able to handle 'abort' being set just as the host
> is claimed.
>
> This allows extra functionality. If __mmc_claim_host() is called
> with an 'abort' pointer which is initialized to '1', it will effect a
> non-blocking 'claim'.
>
> Signed-off-by: NeilBrown <neil@brown.name>
> ---
> drivers/mmc/core/core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 23f10f72e5f3..541c8903dc6b 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -912,10 +912,11 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
> spin_lock_irqsave(&host->lock, flags);
> }
> set_current_state(TASK_RUNNING);
> - if (!stop) {
> + if (!host->claimed || host->claimer == current) {

This seems risky in that regards that it will change the behaviour for
the sdio_irq_thread(). Did you check that?

I guess we could change the sdio_irq_thread() to read it's
sdio_irq_thread_abort value before trying to claim the host?

> host->claimed = 1;
> host->claimer = current;
> host->claim_cnt += 1;
> + stop = 0;
> } else
> wake_up(&host->wq);
> spin_unlock_irqrestore(&host->lock, flags);
>
>

Kind regards
Uffe