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

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>

1 files changed, 4 insertions, 5 deletions

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 461e6a17fb90..2b200c1cfbba 100644
--- 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);
 }
 
 /**
@@ -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);
 }
 
 /**