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 <jasow...@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 majord...@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 linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
