Re: [PATCH] ethdev: fix push new event

[Thomas Monjalon <thomas@monjalon.net>]

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.

> >> If these check is against 'ATTACHED', it goes back to the issue this
> >> patch mentioned.
> >>
> >> The failsafe PMD applications expect sending event before device state
> >> set to 'ATTACHED'.
> >> But other applications expect the device with 'ATTACHED' state before
> >> send event.
> >> They are in conflict with each other. So we can't solve this issue by
> >> adding an
> >> 'RTE_ETH_DEV_ALLOCATED' state.
> >
> >
> > .
>