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.

Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Jin Qian <jinqian@android.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/platform/goldfish/goldfish_pipe.c

@@ -346,7 +346,8 @@ 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;