Re: [PATCH v1] net/dev.c : Remove redundant state settings after waking up

[Wei Wang]

I was not able to see the entire changelog, but I don't think
> -               set_current_state(TASK_INTERRUPTIBLE);
is redundant.

It makes sure that if the previous if statement:
    if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken)
is false, this napi thread yields the CPU to other threads waiting to
be run by calling schedule().

And the napi thread gets into running state again after the next
wake_up_process() is called from ____napi_schedule().


On Tue, Jan 10, 2023 at 4:30 PM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> On Tue, 10 Jan 2023 10:29:20 +0100 Eric Dumazet wrote:
> > > the task status has been set to TASK_RUNNING in shcedule(),
> > > no need to set again here
> >
> > Changelog is rather confusing, this does not match the patch, which
> > removes one set_current_state(TASK_INTERRUPTIBLE);
> >
> > TASK_INTERRUPTIBLE != TASK_RUNNING
> >
> > Patch itself looks okay (but has nothing to do with thread state after
> > schedule()),
> > you should have CC Wei Wang because she
> > authored commit cb038357937e net: fix race between napi kthread mode
> > and busy poll
>
> AFAIU this is the semi-idiomatic way of handling wait loops.
> It's not schedule() that may set the task state to TASK_RUNNING,
> it's whoever wakes the process and makes the "wait condition" true.
> In this case - test_bit(NAPI_STATE_SCHED, &napi->state)
>
> I vote to not futz with this logic.