HACK: ARM: disable sleeping while atomic warning in do_signal

ARM disables interrupts in do_signal, which triggers a warning in
try_to_freeze, see details at https://lkml.org/lkml/2011/8/23/221.
To prevent the warnings, add try_to_freeze_nowarn and call it from
do_signal.

Change-Id: If7482de21c386adc705fa1ac4ecb8c7ece5bb356
Signed-off-by: Colin Cross <ccross@android.com>
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index d68d1b6..eb3a291 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -642,7 +642,7 @@
 		}
 	}
 
-	if (try_to_freeze())
+	if (try_to_freeze_nowarn())
 		goto no_signal;
 
 	/*
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 80e7fae..fa35433 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -41,6 +41,17 @@
 extern void thaw_processes(void);
 extern void thaw_kernel_threads(void);
 
+/*
+ * HACK: prevent sleeping while atomic warnings due to ARM signal handling
+ * disabling irqs
+ */
+static inline bool try_to_freeze_nowarn(void)
+{
+	if (likely(!freezing(current)))
+		return false;
+	return __refrigerator(false);
+}
+
 static inline bool try_to_freeze(void)
 {
 /* This causes problems for ARM targets and is a known
diff --git a/kernel/signal.c b/kernel/signal.c
index 7a06651..e2928c4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2212,7 +2212,7 @@
 	 * Now that we woke up, it's crucial if we're supposed to be
 	 * frozen that we freeze now before running anything substantial.
 	 */
-	try_to_freeze();
+	try_to_freeze_nowarn();
 
 	spin_lock_irq(&sighand->siglock);
 	/*