Re: [PATCH] mmc: fix a deadlock between system suspend and MMC block IO

[Chris Ball <cjb@laptop.org>]

Hi,

On Wed, Jan 11 2012, Nath, Arindam wrote:
> I think we can push this patch now. If someone has any objections, we
> can discuss later.
>
> Acked-by: Arindam Nath <arindam.nath@amd.com>

Thanks, I agree.  Guennadi, I've merged it for 3.3 with the following change:

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index f0b464f..bec0bf2 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2175,6 +2175,7 @@ void mmc_stop_host(struct mmc_host *host)
 
 	mmc_bus_get(host);
 	if (host->bus_ops && !host->bus_dead) {
+		/* Calling bus_ops->remove() with a claimed host can deadlock */
 		if (host->bus_ops->remove)
 			host->bus_ops->remove(host);
 
@@ -2398,7 +2399,9 @@ int mmc_suspend_host(struct mmc_host *host)
 			if (err == -ENOSYS || !host->bus_ops->resume) {
 				/*
 				 * We simply "remove" the card in this case.
-				 * It will be redetected on resume.
+				 * 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);
@@ -2491,7 +2494,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 		if (!host->bus_ops || host->bus_ops->suspend)
 			break;
 
-		/* On 2 occasions above bus_ops->remove() is called unlocked */
+		/* Calling bus_ops->remove() with a claimed host can deadlock */
 		if (host->bus_ops->remove)
 			host->bus_ops->remove(host);
 
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child