platform: goldfish: pipe: don't log when dropping PIPE_ERROR_AGAIN

On PIPE_ERROR_AGAIN, just stopping in the middle of a transfer and
returning the number of bytes actually handled is the right behavior.

Other errors should be returned on the next read() or write() call.
Continue logging those until we confirm nothing actually relies on the
existing (wrong) behavior of dropping errors on the floor.

Change-Id: I578b17ef54cd00d6003bbce1ecf9438e3ae3657e
Signed-off-by: Greg Hackmann <ghackmann@google.com>

drivers/platform/goldfish/goldfish_pipe.c

@@ -356,7 +356,8 @@ static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer,
 			 * cannot change it until we check if any user space
 			 * ABI relies on this behavior.
 			 */
-			pr_info_ratelimited("android_pipe: backend returned error %d on %s\n",
+			if (status != PIPE_ERROR_AGAIN)
+				pr_info_ratelimited("goldfish_pipe: backend returned error %d on %s\n",
 					    status, is_write ? "write" : "read");
 			ret = 0;
 			break;