diff --git a/[refs] b/[refs]
index 2d9f626abcdf..bcabf3ccde37 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5271071b20dee56c01b6b9d8e275611403d3d383
+refs/heads/master: cea443a81c9c6257bf2d00f1392f7d1d4ce03b75
diff --git a/trunk/drivers/i2c/i2c-core.c b/trunk/drivers/i2c/i2c-core.c
index 7161f913de14..ddd1b83f44d4 100644
--- a/trunk/drivers/i2c/i2c-core.c
+++ b/trunk/drivers/i2c/i2c-core.c
@@ -33,6 +33,8 @@
 #include <linux/platform_device.h>
 #include <linux/mutex.h>
 #include <linux/completion.h>
+#include <linux/hardirq.h>
+#include <linux/irqflags.h>
 #include <asm/uaccess.h>
 #include <asm/semaphore.h>
 
@@ -861,7 +863,15 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num)
 		}
 #endif
 
-		mutex_lock_nested(&adap->bus_lock, adap->level);
+		if (in_atomic() || irqs_disabled()) {
+			ret = mutex_trylock(&adap->bus_lock);
+			if (!ret)
+				/* I2C activity is ongoing. */
+				return -EAGAIN;
+		} else {
+			mutex_lock_nested(&adap->bus_lock, adap->level);
+		}
+
 		ret = adap->algo->master_xfer(adap,msgs,num);
 		mutex_unlock(&adap->bus_lock);