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authorGuennadi Liakhovetski <g.liakhovetski@gmx.de>2012-01-04 15:28:45 +0100
committerChris Ball <cjb@laptop.org>2012-01-12 15:17:17 -0500
commit0db13fc2abbb0b1a8d8efee20dfbd7f3c5d54022 (patch)
tree9932b8a8bca14f536e9a23f905919d9ee9c1a10a /drivers/mmc
parent3abc1e804253add41990cbe1461e79c1165108e0 (diff)
downloadop-kernel-dev-0db13fc2abbb0b1a8d8efee20dfbd7f3c5d54022.zip
op-kernel-dev-0db13fc2abbb0b1a8d8efee20dfbd7f3c5d54022.tar.gz
mmc: fix a deadlock between system suspend and MMC block IO
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>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/core/core.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 1da45e0..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);
@@ -2491,11 +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);
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