mmc: fix a deadlock between system suspend and MMC block IO (0db13fc2) · Commits · 戴 / test

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>

drivers/mmc/core/core.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -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);

Admin message