Commit 3a574919 authored Feb 27, 2018 by Ulf Hansson

mmc: core: Avoid hanging to claim host for mmc via some nested calls



As the block layer, since the conversion to blkmq, claims the host using a
context, a following nested call to mmc_claim_host(), which isn't using a
context, may hang.

Calling mmc_interrupt_hpi() and mmc_read_bkops_status() via the mmc block
layer, may suffer from this problem, as these functions are calling
mmc_claim|release_host().

Let's fix the problem by removing the calls to mmc_claim|release_host()
from the above mentioned functions and instead make the callers responsible
of claiming/releasing the host. As a matter of fact, the existing callers
already deals with it.

Fixes: 81196976 ("mmc: block: Add blk-mq support")
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>

parent 5b43df8b

drivers/mmc/core/mmc_ops.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -848,7 +848,6 @@ int mmc_interrupt_hpi(struct mmc_card *card)
		return 1;
		}

		mmc_claim_host(card->host);
		err = mmc_send_status(card, &status);
		if (err) {
		pr_err("%s: Get card status fail\n", mmc_hostname(card->host));
		@@ -890,7 +889,6 @@ int mmc_interrupt_hpi(struct mmc_card *card)
		} while (!err);

		out:
		mmc_release_host(card->host);
		return err;
		}

		@@ -932,9 +930,7 @@ static int mmc_read_bkops_status(struct mmc_card *card)
		int err;
		u8 *ext_csd;

		mmc_claim_host(card->host);
		err = mmc_get_ext_csd(card, &ext_csd);
		mmc_release_host(card->host);
		if (err)
		return err;