[2/3] mmc: protect against clockgate races

Commit Message

Linus Walleij Nov. 16, 2010, 4:56 p.m. UTC

None

Patch

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index f74b386..92e3370 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -68,9 +68,9 @@  static void mmc_host_clk_gate_delayed(struct mmc_host *host)
 	unsigned long flags;
 
 	if (!freq) {
-		pr_err("%s: frequency set to 0 in disable function, "
-		       "this means the clock is already disabled.\n",
-		       mmc_hostname(host));
+		pr_debug("%s: frequency set to 0 in disable function, "
+			 "this means the clock is already disabled.\n",
+			 mmc_hostname(host));
 		return;
 	}
 	/*
@@ -94,6 +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);
 	spin_lock_irqsave(&host->clk_lock, flags);
 	if (!host->clk_requests) {
 		spin_unlock_irqrestore(&host->clk_lock, flags);
@@ -103,6 +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);
 }
 
 /*
@@ -128,6 +130,7 @@  void mmc_host_clk_ungate(struct mmc_host *host)
 {
 	unsigned long flags;
 
+	mutex_lock(&host->clk_gate_mutex);
 	spin_lock_irqsave(&host->clk_lock, flags);
 	if (host->clk_gated) {
 		spin_unlock_irqrestore(&host->clk_lock, flags);
@@ -137,6 +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);
 }
 
 /**
@@ -214,6 +218,7 @@  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 955bc10..53496bb 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -178,6 +178,7 @@  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 */