[RFC PATCH 1/3] mmc: sdio: Don't use abort-able claim host method from SDIO IRQ thread

[Ulf Hansson <ulf.hansson@linaro.org>]

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.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 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 */
 
-- 
2.7.4