mmc: fix a race between card-detect rescan and clock-gate work instances
Guennadi Liakhovetski [Fri, 15 Apr 2011 18:08:19 +0000 (20:08 +0200)]
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>
Cc: <stable@kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/host.c
include/linux/mmc/host.h

index 461e6a1..2b200c1 100644 (file)
@@ -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);
 }
 
 /**
@@ -215,7 +215,6 @@ 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);
 }
 
 /**
index bcb793e..eb792cb 100644 (file)
@@ -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 */