mmc: core: Do not pre-claim host in suspend

Since SDIO drivers may want to do some SDIO operations in their suspend
callback functions, we must not keep the host claimed when calling them.

Daniel Drake reported that libertas_sdio encountered a deadlock in its
suspend function.

Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Tested-by: Daniel Drake <dsd@laptop.org>
[stable@: please apply to 3.2-stable and 3.3-stable]
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 20 insertions, 35 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index e541efb..ba821fe 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2238,6 +2238,7 @@ int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
 			mmc_card_is_removable(host))
 		return err;
 
+	mmc_claim_host(host);
 	if (card && mmc_card_mmc(card) &&
 			(card->ext_csd.cache_size > 0)) {
 		enable = !!enable;
@@ -2255,6 +2256,7 @@ int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
 				card->ext_csd.cache_ctrl = enable;
 		}
 	}
+	mmc_release_host(host);
 
 	return err;
 }
@@ -2272,49 +2274,32 @@ int mmc_suspend_host(struct mmc_host *host)
 
 	cancel_delayed_work(&host->detect);
 	mmc_flush_scheduled_work();
-	if (mmc_try_claim_host(host)) {
-		err = mmc_cache_ctrl(host, 0);
-		mmc_release_host(host);
-	} else {
-		err = -EBUSY;
-	}
 
+	err = mmc_cache_ctrl(host, 0);
 	if (err)
 		goto out;
 
 	mmc_bus_get(host);
 	if (host->bus_ops && !host->bus_dead) {
 
-		/*
-		 * A long response time is not acceptable for device drivers
-		 * when doing suspend. Prevent mmc_claim_host in the suspend
-		 * sequence, to potentially wait "forever" by trying to
-		 * pre-claim the host.
-		 */
-		if (mmc_try_claim_host(host)) {
-			if (host->bus_ops->suspend) {
-				err = host->bus_ops->suspend(host);
-			}
-			mmc_release_host(host);
+		if (host->bus_ops->suspend)
+			err = host->bus_ops->suspend(host);
 
-			if (err == -ENOSYS || !host->bus_ops->resume) {
-				/*
-				 * We simply "remove" the card in this case.
-				 * It will be redetected on resume.  (Calling
-				 * bus_ops->remove() with a claimed host can
-				 * deadlock.)
-				 */
-				if (host->bus_ops->remove)
-					host->bus_ops->remove(host);
-				mmc_claim_host(host);
-				mmc_detach_bus(host);
-				mmc_power_off(host);
-				mmc_release_host(host);
-				host->pm_flags = 0;
-				err = 0;
-			}
-		} else {
-			err = -EBUSY;
+		if (err == -ENOSYS || !host->bus_ops->resume) {
+			/*
+			 * We simply "remove" the card in this case.
+			 * It will be redetected on resume.  (Calling
+			 * bus_ops->remove() with a claimed host can
+			 * deadlock.)
+			 */
+			if (host->bus_ops->remove)
+				host->bus_ops->remove(host);
+			mmc_claim_host(host);
+			mmc_detach_bus(host);
+			mmc_power_off(host);
+			mmc_release_host(host);
+			host->pm_flags = 0;
+			err = 0;
 		}
 	}
 	mmc_bus_put(host);