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mmc: dw_mmc: fix race with request and removal

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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: James Hogan <james.hogan@imgtec.com>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
James Hogan 2011-06-24 13:55:10 +01:00 committed by Chris Ball
parent b40af3aa77
commit 7456caae37
1 changed files with 11 additions and 4 deletions
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15
drivers/mmc/host/dw_mmc.c
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@ -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)