On Fri, Sep 18, 2020 at 10:48 AM Eric Dumazet <eduma...@google.com> wrote:
>
>
> Also, I would try using synchronize_rcu() instead of the first
s/synchronize_rcu/rcu_barrier/ of course :/
> msleep(), this might avoid all msleep() calls in your case.
>
> Patch without the macros to see the general idea :
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index
> 266073e300b5fc21440ea8f8ffc9306a1fc9f370..2d3b65034bc0dd99017dea846e6c0a966f1207ee
> 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -9989,7 +9989,7 @@ EXPORT_SYMBOL(netdev_refcnt_read);
> static void netdev_wait_allrefs(struct net_device *dev)
> {
> unsigned long rebroadcast_time, warning_time;
> - int refcnt;
> + int wait = 0, refcnt;
>
> linkwatch_forget_dev(dev);
>
> @@ -10023,8 +10023,13 @@ static void netdev_wait_allrefs(struct net_device
> *dev)
> rebroadcast_time = jiffies;
> }
>
> - msleep(250);
> -
> + if (!wait) {
> + synchronize_rcu();
rcu_barrier();
> + wait = 1;
> + } else {
> + msleep(wait);
> + wait = min(wait << 1, 250);
> + }
> refcnt = netdev_refcnt_read(dev);
>
> if (refcnt && time_after(jiffies, warning_time + 10 * HZ)) {
