Message ID | 1357378446-19656-4-git-send-email-jasowang@redhat.com |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
On Sat, 2013-01-05 at 17:34 +0800, Jason Wang wrote: > Currently, tun_chr_poll() returns POLLERR after waitqueue adding during device > unregistration. This would confuse some of its user such as vhost which assume > when POLLERR is returned, it wasn't added to the waitqueue. Fix this by > returning POLLERR before adding to waitqueue. > > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- > drivers/net/tun.c | 5 +---- > 1 files changed, 1 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index fbd106e..f9c0049 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -886,7 +886,7 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) > struct sock *sk; > unsigned int mask = 0; > > - if (!tun) > + if (!tun || tun->dev->reg_state != NETREG_REGISTERED) > return POLLERR; > > sk = tfile->socket.sk; > @@ -903,9 +903,6 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) > sock_writeable(sk))) > mask |= POLLOUT | POLLWRNORM; > > - if (tun->dev->reg_state != NETREG_REGISTERED) > - mask = POLLERR; > - > tun_put(tun); > return mask; > } This patch is buggy. First, the caller assuming POLLERR means poll_wait() was not called is wrong. Secondly, you add a ref leak. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 01/06/2013 03:37 AM, Eric Dumazet wrote: > On Sat, 2013-01-05 at 17:34 +0800, Jason Wang wrote: >> Currently, tun_chr_poll() returns POLLERR after waitqueue adding during device >> unregistration. This would confuse some of its user such as vhost which assume >> when POLLERR is returned, it wasn't added to the waitqueue. Fix this by >> returning POLLERR before adding to waitqueue. >> >> Signed-off-by: Jason Wang <jasowang@redhat.com> >> --- >> drivers/net/tun.c | 5 +---- >> 1 files changed, 1 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >> index fbd106e..f9c0049 100644 >> --- a/drivers/net/tun.c >> +++ b/drivers/net/tun.c >> @@ -886,7 +886,7 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) >> struct sock *sk; >> unsigned int mask = 0; >> >> - if (!tun) >> + if (!tun || tun->dev->reg_state != NETREG_REGISTERED) >> return POLLERR; >> >> sk = tfile->socket.sk; >> @@ -903,9 +903,6 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) >> sock_writeable(sk))) >> mask |= POLLOUT | POLLWRNORM; >> >> - if (tun->dev->reg_state != NETREG_REGISTERED) >> - mask = POLLERR; >> - >> tun_put(tun); >> return mask; >> } > This patch is buggy. > > First, the caller assuming POLLERR means poll_wait() was not called is > wrong. True, looks like vhost need to check the poll->wqh before trying to remove from waitqueue instead of this wrong assumption. And then we can drop the whole tx polling state. > > Secondly, you add a ref leak. Yes, will drop this patch. Thanks. > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index fbd106e..f9c0049 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -886,7 +886,7 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) struct sock *sk; unsigned int mask = 0; - if (!tun) + if (!tun || tun->dev->reg_state != NETREG_REGISTERED) return POLLERR; sk = tfile->socket.sk; @@ -903,9 +903,6 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) sock_writeable(sk))) mask |= POLLOUT | POLLWRNORM; - if (tun->dev->reg_state != NETREG_REGISTERED) - mask = POLLERR; - tun_put(tun); return mask; }
Currently, tun_chr_poll() returns POLLERR after waitqueue adding during device unregistration. This would confuse some of its user such as vhost which assume when POLLERR is returned, it wasn't added to the waitqueue. Fix this by returning POLLERR before adding to waitqueue. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/net/tun.c | 5 +---- 1 files changed, 1 insertions(+), 4 deletions(-)