mmc: fix a race between card-detect rescan and clock-gate work instances

BugLink: http://bugs.launchpad.net/bugs/780546

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>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index cef4046..0dd342f 100644 (file)
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -94,7 +94,7 @@ static void mmc_host_clk_gate_delayed(struct mmc_host *host)
                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(struct mmc_host *host)
                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 *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)
        }
        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(struct mmc_host *host)
        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);
 }
 
 /**

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index bcb793e..eb792cb 100644 (file)
--- 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 */