We play with a wait queue even if socket is
non blocking. This is an obvious waste.
Besides, it will prevent calling the non blocking
variant when current is not valid.

Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
 drivers/net/tun.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 807815f..7cb105c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1293,7 +1293,8 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct 
tun_file *tfile,
        if (unlikely(!noblock))
                add_wait_queue(&tfile->wq.wait, &wait);
        while (len) {
-               current->state = TASK_INTERRUPTIBLE;
+               if (unlikely(!noblock))
+                       current->state = TASK_INTERRUPTIBLE;
 
                /* Read frames from the queue */
                if (!(skb = skb_dequeue(&tfile->socket.sk->sk_receive_queue))) {
@@ -1320,9 +1321,10 @@ static ssize_t tun_do_read(struct tun_struct *tun, 
struct tun_file *tfile,
                break;
        }
 
-       current->state = TASK_RUNNING;
-       if (unlikely(!noblock))
+       if (unlikely(!noblock)) {
+               current->state = TASK_RUNNING;
                remove_wait_queue(&tfile->wq.wait, &wait);
+       }
 
        return ret;
 }
-- 
MST
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