ARM: SAMSUNG: fix race in s3c_adc_start for ADC

commit 8265981b upstream.

Checking for adc->ts_pend already claimed should be done with the
lock held.
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/arm/plat-samsung/adc.c

@@ -157,11 +157,13 @@ int s3c_adc_start(struct s3c_adc_client *client,
 		return -EINVAL;
 	}
 
-	if (client->is_ts && adc->ts_pend)
-		return -EAGAIN;
-
 	spin_lock_irqsave(&adc->lock, flags);
 
+	if (client->is_ts && adc->ts_pend) {
+		spin_unlock_irqrestore(&adc->lock, flags);
+		return -EAGAIN;
+	}
+
 	client->channel = channel;
 	client->nr_samples = nr_samples;