On 11/05/17 15:39, Ulf Hansson wrote:
> In a step to simplify the use of the lock, mmc_claim|release_host(), let's
> change the SDIO IRQ thread to move away from using the abort-able claim
> host method.
>
> In the SDIO IRQ thread case, we can instead check the numbers of SDIO IRQs
> that are currently claimed via host->sdio_irqs, as this field is protected
> from updates unless the host is claimed. When host->sdio_irqs has become
> zero, it means the SDIO func driver(s) has released the SDIO IRQ, then we
> can bail out and stop running the SDIO IRQ thread.
Does that work? It looks a like kthread_stop() will wait on the thread,
which is waiting to claim the host, which is claimed by the caller of
sdio_card_irq_put() which called kthread_stop() i.e. deadlock.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---
> drivers/mmc/core/sdio_irq.c | 10 ++++++----
> include/linux/mmc/host.h | 1 -
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
> index 6d4b720..95f7a09 100644
> --- a/drivers/mmc/core/sdio_irq.c
> +++ b/drivers/mmc/core/sdio_irq.c
> @@ -137,9 +137,13 @@ static int sdio_irq_thread(void *_host)
> * holding of the host lock does not cover too much work
> * that doesn't require that lock to be held.
> */
> - ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort);
> - if (ret)
> + mmc_claim_host(host);
> + if (!host->sdio_irqs) {
> + ret = 1;
> + mmc_release_host(host);
> break;
> + }
> +
> ret = process_sdio_pending_irqs(host);
> host->sdio_irq_pending = false;
> mmc_release_host(host);
> @@ -195,7 +199,6 @@ static int sdio_card_irq_get(struct mmc_card *card)
>
> if (!host->sdio_irqs++) {
> if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) {
> - atomic_set(&host->sdio_irq_thread_abort, 0);
> host->sdio_irq_thread =
> kthread_run(sdio_irq_thread, host,
> "ksdioirqd/%s", mmc_hostname(host));
> @@ -223,7 +226,6 @@ static int sdio_card_irq_put(struct mmc_card *card)
>
> if (!--host->sdio_irqs) {
> if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) {
> - atomic_set(&host->sdio_irq_thread_abort, 1);
> kthread_stop(host->sdio_irq_thread);
> } else if (host->caps & MMC_CAP_SDIO_IRQ) {
> host->ops->enable_sdio_irq(host, 0);
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 21385ac..8a4131f 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -359,7 +359,6 @@ struct mmc_host {
> unsigned int sdio_irqs;
> struct task_struct *sdio_irq_thread;
> bool sdio_irq_pending;
> - atomic_t sdio_irq_thread_abort;
>
> mmc_pm_flag_t pm_flags; /* requested pm features */
>
>
