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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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