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    Subject[patch 15/38] mmc: fix a race between card-detect rescan and clock-gate work instances
    2.6.38-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

    commit 26fc8775b51484d8c0a671198639c6d5ae60533e upstream.

    Currently there is a race in the MMC core between a card-detect
    rescan work and the clock-gating work, scheduled from a command
    completion. Fix it by removing the dedicated clock-gating mutex
    and using the MMC standard locking mechanism instead.

    Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
    Cc: Simon Horman <horms@verge.net.au>
    Cc: Magnus Damm <damm@opensource.se>
    Acked-by: Linus Walleij <linus.walleij@linaro.org>
    Signed-off-by: Chris Ball <cjb@laptop.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    drivers/mmc/core/host.c | 9 ++++-----
    include/linux/mmc/host.h | 1 -
    2 files changed, 4 insertions(+), 6 deletions(-)

    --- a/drivers/mmc/core/host.c
    +++ b/drivers/mmc/core/host.c
    @@ -94,7 +94,7 @@ static void mmc_host_clk_gate_delayed(st
    spin_unlock_irqrestore(&host->clk_lock, flags);
    return;
    }
    - mutex_lock(&host->clk_gate_mutex);
    + mmc_claim_host(host);
    spin_lock_irqsave(&host->clk_lock, flags);
    if (!host->clk_requests) {
    spin_unlock_irqrestore(&host->clk_lock, flags);
    @@ -104,7 +104,7 @@ static void mmc_host_clk_gate_delayed(st
    pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
    }
    spin_unlock_irqrestore(&host->clk_lock, flags);
    - mutex_unlock(&host->clk_gate_mutex);
    + mmc_release_host(host);
    }

    /*
    @@ -130,7 +130,7 @@ void mmc_host_clk_ungate(struct mmc_host
    {
    unsigned long flags;

    - mutex_lock(&host->clk_gate_mutex);
    + mmc_claim_host(host);
    spin_lock_irqsave(&host->clk_lock, flags);
    if (host->clk_gated) {
    spin_unlock_irqrestore(&host->clk_lock, flags);
    @@ -140,7 +140,7 @@ void mmc_host_clk_ungate(struct mmc_host
    }
    host->clk_requests++;
    spin_unlock_irqrestore(&host->clk_lock, flags);
    - mutex_unlock(&host->clk_gate_mutex);
    + mmc_release_host(host);
    }

    /**
    @@ -218,7 +218,6 @@ static inline void mmc_host_clk_init(str
    host->clk_gated = false;
    INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
    spin_lock_init(&host->clk_lock);
    - mutex_init(&host->clk_gate_mutex);
    }

    /**
    --- a/include/linux/mmc/host.h
    +++ b/include/linux/mmc/host.h
    @@ -183,7 +183,6 @@ struct mmc_host {
    struct work_struct clk_gate_work; /* delayed clock gate */
    unsigned int clk_old; /* old clock value cache */
    spinlock_t clk_lock; /* lock for clk fields */
    - struct mutex clk_gate_mutex; /* mutex for clock gating */
    #endif

    /* host specific block data */



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