On Thu, 2021-08-26 at 07:15 +0000, Xia, Chenbo wrote:
> Hi Adrew & Xueming,
>
> > -----Original Message-----
> > From: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
> > Sent: Tuesday, August 24, 2021 11:41 PM
> > To: Xueming(Steven) Li <xuemi...@nvidia.com>
> > Cc: dev@dpdk.org; Maxime Coquelin <maxime.coque...@redhat.com>; Xia, Chenbo
> > <chenbo....@intel.com>
> > Subject: Re: [dpdk-dev] [PATCH] net/virtio: wait device ready in device
> > reset
> >
> > On 8/23/21 4:54 PM, Xueming(Steven) Li wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
> > > > Sent: Monday, August 23, 2021 5:57 PM
> > > > To: Xueming(Steven) Li <xuemi...@nvidia.com>
> > > > Cc: dev@dpdk.org; Maxime Coquelin <maxime.coque...@redhat.com>; Chenbo
> > > > Xia
> > <chenbo....@intel.com>
> > > > Subject: Re: [dpdk-dev] [PATCH] net/virtio: wait device ready in device
> > reset
> > > >
> > > > On 8/23/21 9:39 AM, Xueming Li wrote:
> > > > > According to virtio spec, the device MUST reset when 0 is written to
> > > > > device_status, and present a 0 in device_status once that is done.
> > > > >
> > > > > This patch adds the missing part of waiting status 0 in reset
> > > > > function.
> > > > >
> > > > > Signed-off-by: Xueming Li <xuemi...@nvidia.com>
> > > > > ---
> > > > > drivers/net/virtio/virtio.c | 7 +++++--
> > > > > 1 file changed, 5 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/net/virtio/virtio.c b/drivers/net/virtio/virtio.c
> > > > > index 7e1e77797f..f003f612d6 100644
> > > > > --- a/drivers/net/virtio/virtio.c
> > > > > +++ b/drivers/net/virtio/virtio.c
> > > > > @@ -3,6 +3,8 @@
> > > > > * Copyright(c) 2020 Red Hat, Inc.
> > > > > */
> > > > >
> > > > > +#include <unistd.h>
> > > > > +
> > > > > #include "virtio.h"
> > > > >
> > > > > uint64_t
> > > > > @@ -39,8 +41,9 @@ void
> > > > > virtio_reset(struct virtio_hw *hw)
> > > > > {
> > > > > VIRTIO_OPS(hw)->set_status(hw, VIRTIO_CONFIG_STATUS_RESET);
> > > > > - /* flush status write */
> > > > > - VIRTIO_OPS(hw)->get_status(hw);
> > > > > + /* Flush status write and wait device ready. */
> > > > > + while (VIRTIO_OPS(hw)->get_status(hw) !=
> > > > > VIRTIO_CONFIG_STATUS_RESET)
> > > > > + usleep(1000L);
> > > >
> > > > Don't we need a protection against forever loop here?
> > >
> > > Good question, ideally we need, kernel driver function vp_reset() seems to
> > have same issue.
> >
> > Yes, I've seen it.
> >
> > > How about leaving an error message before return?
> >
> > @Maxime, @Chenbo, what do you think?
>
> I would vote for waiting for some time before return rather than forever loop
> and error message is needed.
>
> My understanding is for kernel, it's fine to sleep forever as kernel could
> schedule
> it but for DPDK, it will lead to main lcore unable to do other things but
> sleep
> forever. Meanwhile, users will see the app stuck but don't know what's wrong
> here.
>
> Thanks,
> Chenbo
>
Hi all, thanks for you sugestion, new version posted:
https://mails.dpdk.org/archives/dev/2021-September/219866.html
>
