From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH] tun: don't look at current when non-blocking Date: Tue, 08 Oct 2013 10:50:23 +0800 Message-ID: <525372EF.9090307@redhat.com> References: <20131006182512.GA16504@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , Eric Dumazet , Pavel Emelyanov To: "Michael S. Tsirkin" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: In-Reply-To: <20131006182512.GA16504@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 10/07/2013 02:25 AM, Michael S. Tsirkin wrote: > 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 > --- Acked-by: Jason Wang > 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; > }