Re: [PATCH] ethdev: fix push new event

[Thomas Monjalon <thomas@monjalon.net>]

11/06/2022 10:59, lihuisong (C):
> 在 2022/6/7 14:44, Thomas Monjalon 写道:
> > 07/06/2022 03:23, lihuisong (C):
> >> 在 2022/6/3 15:42, Thomas Monjalon 写道:
> >>> 02/06/2022 13:24, lihuisong (C):
> >>>> 在 2022/5/30 19:10, Ferruh Yigit 写道:
> >>>>> On 5/30/2022 9:28 AM, Thomas Monjalon wrote:
> >>>>>> [CAUTION: External Email]
> >>>>>>
> >>>>>> 28/05/2022 10:53, lihuisong (C):
> >>>>>>> 在 2022/5/23 22:36, Thomas Monjalon 写道:
> >>>>>>>> 23/05/2022 11:51, David Marchand:
> >>>>>>>>> On Sat, May 21, 2022 at 8:57 AM Min Hu
> >>>>>>>>> (Connor)<humin29@huawei.com>  wrote:
> >>>>>>>>>> From: Huisong Li<lihuisong@huawei.com>
> >>>>>>>>>>
> >>>>>>>>>> The 'state' in struct rte_eth_dev may be used to update some
> >>>>>>>>>> information
> >>>>>>>>>> when app receive these events. For example, when app receives a
> >>>>>>>>>> new event,
> >>>>>>>>>> app may get the socket id of this port by calling
> >>>>>>>>>> rte_eth_dev_socket_id to
> >>>>>>>>>> setup the attached port. The 'state' is used in
> >>>>>>>>>> rte_eth_dev_socket_id.
> >>>>>>>>>>
> >>>>>>>>>> If the state isn't modified to RTE_ETH_DEV_ATTACHED before
> >>>>>>>>>> pushing the new
> >>>>>>>>>> event, app will get the socket id failed. So this patch moves
> >>>>>>>>>> pushing event
> >>>>>>>>>> operation after the state updated.
> >>>>>>>>>>
> >>>>>>>>>> Fixes: 99a2dd955fba ("lib: remove librte_ prefix from directory
> >>>>>>>>>> names")
> >>>>>>>>> A patch moving code is unlikely to be at fault.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> Looking at the patch which moved those notifications in this point of
> >>>>>>>>> the code, the state update was pushed after the notification on
> >>>>>>>>> purpose.
> >>>>>>>>> See be8cd210379a ("ethdev: fix port probing notification")
> >>>>>>>>>
> >>>>>>>>>         ethdev: fix port probing notification
> >>>>>>>>>
> >>>>>>>>>         The new device was notified as soon as it was allocated.
> >>>>>>>>>         It leads to use a device which is not yet initialized.
> >>>>>>>>>
> >>>>>>>>>         The notification must be published after the initialization
> >>>>>>>>> is done
> >>>>>>>>>         by the PMD, but before the state is changed, in order to let
> >>>>>>>>>         notified entities taking ownership before general availability.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> Do we need an intermediate state during probing?
> >>>>>>>> Possibly. Currently we have only 3 states:
> >>>>>>>>        RTE_ETH_DEV_UNUSED
> >>>>>>>>        RTE_ETH_DEV_ATTACHED
> >>>>>>>>        RTE_ETH_DEV_REMOVED
> >>>>>>>>
> >>>>>>>> We may add RTE_ETH_DEV_ALLOCATED just before calling
> >>>>>>>>        rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_NEW, NULL);
> >>>>>>>> Then we would need to check against RTE_ETH_DEV_ALLOCATED
> >>>>>>>> in some ethdev functions.
> >>>>>>>>
> >>>>>>> Hi, Thomas,
> >>>>>>>
> >>>>>>> Do you mean that we need to modify some funcions like following?
> >>>>>>>
> >>>>>>> int rte_eth_dev_is_valid_port(uint16_t port_id)
> >>>>>>> {
> >>>>>>>         if (port_id >= RTE_MAX_ETHPORTS ||
> >>>>>>>             (rte_eth_devices[port_id].state != *RTE_ETH_DEV_ALLOCATED*))
> >>>>>>>             return 0;
> >>>>> Won't this mark ATTACHED devices as invalid?
> >>>> Yes, You are right.
> >>>>
> >>>>> If the state flow will be as UNUSED -> ALLOCATED -> ATTACHED, above
> >>>>> check should be against 'ATTACHED' I think.
> >>> It should validate both ALLOCATED and ATTACHED.
> >> Actually, we can only pick one, because it is an enumeration.
> > You can check it is either one state or the other.
> uint16_t
> rte_eth_find_next(uint16_t port_id)
> {
>      while (port_id < RTE_MAX_ETHPORTS &&
>             !(rte_eth_devices[port_id].state == RTE_ETH_DEV_ALLOCATED ||
>               rte_eth_devices[port_id].state == RTE_ETH_DEV_ATTACHED))
>          port_id++;
> 
>      if (port_id >= RTE_MAX_ETHPORTS)
>          return RTE_MAX_ETHPORTS;
> 
>      return port_id;
> }
> like this, right? If so, adding 'ALLOCATED' and setting to 'ALLOCATED' 
> is the same with
> setting to 'ATTACHED' before sending new event.
> They both meet the requirements mentioned in this patch that the device 
> is a valid port
> when applications receive a new event.

Yes, when receiving the event, the port would valid
in state ALLOCATED.
Then we can set as ATTACHED when definitely initialized,
after the notifications.

> However, if device is taken by failsafe PMD as sub-device, the 
> processing above
> still doesn't satisfy the purpose of failsafe PMD when this sub-device 
> push new event.

I don't understand why you think failsafe is not satisfied.
> 
> I don't know if I'm missing something. Can you explain it, Ferruh and 
> Thomas?

Please explain what you think is failing with failsafe.