netdev - Re: [PATCH net 2/2] net/sched: add delete_empty() to filters and use it in cls

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Date:   Tue, 24 Dec 2019 15:53:54 +0100
From:   Davide Caratti <dcaratti@...hat.com>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [PATCH net 2/2] net/sched: add delete_empty() to filters and
 use it in cls_flower

hello Jamal and Vlad,

thanks for looking at this.

On Tue, 2019-12-24 at 11:48 +0000, Vlad Buslov wrote:
> I guess we can reduce this code to just:
> 
> spin_lock(&tp->lock);
> tp->deleting = idr_is_empty(&head->handle_idr);
> spin_unlock(&tp->lock);

on the current version of delete_empty() for cls_flower, we are assuming
an empty filter also when the IDR is allocated, but its refcount is zero:

1931         idr_for_each_entry_continue_ul(&head->handle_idr, f, tmp, id) {
1932                 /* don't return filters that are being deleted */
1933                 if (!refcount_inc_not_zero(&f->refcnt))
1934                         continue;
1935                 if (arg->fn(tp, f, arg) < 0) {
1936                         __fl_put(f);
1937                         arg->stop = 1;
1938                         break;
1939                 }
1940                 __fl_put(f);
1941                 arg->count++;
1942         }

but probably this is relevant to dump(), not delete(). Correct?

 # ./tdc.py -c flower -d enp2s0

^^ I'm running several loops of this, just to make sure. If I don't find
anything relevant in few hours, I will send a v2.
thanks!
-- 
davide