netdev - Re: [PATCH net-next] net: make napi_disable() symmetric with enable

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Date:   Fri, 24 Sep 2021 13:21:36 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, weiwan@...gle.com,
        xuanzhuo@...ux.alibaba.com
Subject: Re: [PATCH net-next] net: make napi_disable() symmetric with enable

On Fri, 24 Sep 2021 07:30:30 -0700 Eric Dumazet wrote:
> >  void napi_disable(struct napi_struct *n)
> >  {
> > +	unsigned long val, new;
> > +
> >  	might_sleep();
> >  	set_bit(NAPI_STATE_DISABLE, &n->state);
> >  
> > -	while (test_and_set_bit(NAPI_STATE_SCHED, &n->state))
> > -		msleep(1);
> > -	while (test_and_set_bit(NAPI_STATE_NPSVC, &n->state))
> > -		msleep(1);
> > +	do {
> > +		val = READ_ONCE(n->state);
> > +		if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
> > +			msleep(1);  
> 
> Patch seems good to me.
> 
> We also could replace this pessimistic msleep(1) with more opportunistic usleep_range(20, 200)

Will do, thanks!