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mmc: fix a deadlock between system suspend and MMC block IO

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Performing MMC block IO with simultaneous STR can lead to a deadlock: the
mmc_pm_notify() function claims the host and then calls bus .remove()
method, which lands in mmc_blk_remove(), which calls mmc_blk_remove_req()
then it goes to -> mmc_cleanup_queue() -> kthread_stop(), which waits for
the mmc-block thread to stop. If the mmc-block thread at that time is
processing block requests, it will also try to claim the host in
mmc_blk_issue_rq() and block there. This patch fixes the problem by
calling .remove() before claiming the host.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Guennadi Liakhovetski 2012-01-04 15:28:45 +01:00 committed by Chris Ball
parent 3abc1e8042
commit 0db13fc2ab
1 changed files with 6 additions and 3 deletions
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9
drivers/mmc/core/core.c
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@ -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);
@ -2491,11 +2494,11 @@ int mmc_pm_notify(struct notifier_block *notify_block,
if (!host->bus_ops || host->bus_ops->suspend)
break;
mmc_claim_host(host);
/* 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);