Revert "tun: remove useless codes in tun_chr_aio_read() and tun_recvmsg()"

This reverts commit 73713357ab58aacda1af715bb5a623528dbbfd79.

MSG_TRUNC handling was broken and is going to be fixed in
the 'net' tree, so revert this.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index bbb693512918..3c5a8d8cde50 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1354,6 +1354,7 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
 
         ret = tun_do_read(tun, tfile, iv, len,
                           file->f_flags & O_NONBLOCK);
+        ret = min_t(ssize_t, ret, len);
         if (ret > 0)
                 iocb->ki_pos = ret;
 out:
@@ -1454,6 +1455,10 @@ static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
         }
         ret = tun_do_read(tun, tfile, m->msg_iov, total_len,
                           flags & MSG_DONTWAIT);
+        if (ret > total_len) {
+                m->msg_flags |= MSG_TRUNC;
+                ret = flags & MSG_TRUNC ? ret : total_len;
+        }
 out:
         tun_put(tun);
         return ret;