lib/sysfs: stop before calling write with zero bytes

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
index dc178b3d..4fd0d47f 100644
--- a/lib/igt_sysfs.c
+++ b/lib/igt_sysfs.c
@@ -63,6 +63,8 @@ static int readN(int fd, char *buf, int len)
 			return total ?: ret;
 
 		total += ret;
+		if (total == len)
+			return total;
 	} while (1);
 }
 
@@ -78,6 +80,8 @@ static int writeN(int fd, const char *buf, int len)
 			return total ?: ret;
 
 		total += ret;
+		if (total == len)
+			return total;
 	} while (1);
 }