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Commit 7456caae authored by James Hogan's avatar James Hogan Committed by Chris Ball
Browse files

mmc: dw_mmc: fix race with request and removal 



When a request is made, the card presence is checked and the request is
queued. These two parts must be atomic with respect to card removal, or
a card removal could be handled in between, and the new request wouldn't
get cancelled until another card was inserted. Therefore move the
spinlock protection from dw_mci_queue_request() up into dw_mci_request()
to cover the presence check.

Note that the test_bit() used for the presence check isn't atomic
itself, so should have been protected by a spinlock anyway.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Acked-by: default avatarWill Newton <will.newton@imgtec.com>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent b40af3aa

drivers/mmc/host/dw_mmc.c

+11 −4
Original line number Diff line number Diff line
@@ -625,13 +625,13 @@ static void dw_mci_start_request(struct dw_mci *host, 
		host->stop_cmdr = dw_mci_prepare_command(slot->mmc, mrq->stop);

}



/* must be called with host->lock held */

static void dw_mci_queue_request(struct dw_mci *host, struct dw_mci_slot *slot,

				 struct mmc_request *mrq)

{

	dev_vdbg(&slot->mmc->class_dev, "queue request: state=%d\n",

		 host->state);



	spin_lock_bh(&host->lock);

	slot->mrq = mrq;



	if (host->state == STATE_IDLE) {
@@ -640,8 +640,6 @@ static void dw_mci_queue_request(struct dw_mci *host, struct dw_mci_slot *slot, 
	} else {

		list_add_tail(&slot->queue_node, &host->queue);

	}



	spin_unlock_bh(&host->lock);

}



static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
@@ -651,14 +649,23 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq) 


	WARN_ON(slot->mrq);



	/*

	 * The check for card presence and queueing of the request must be

	 * atomic, otherwise the card could be removed in between and the

	 * request wouldn't fail until another card was inserted.

	 */

	spin_lock_bh(&host->lock);



	if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) {

		spin_unlock_bh(&host->lock);

		mrq->cmd->error = -ENOMEDIUM;

		mmc_request_done(mmc, mrq);

		return;

	}



	/* We don't support multiple blocks of weird lengths. */

	dw_mci_queue_request(host, slot, mrq);



	spin_unlock_bh(&host->lock);

}



static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)