From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vlad Buslov <vladbu@mellanox.com>
Subject: Re: [PATCH net-next v2 08/10] net: sched: protect block idr with spinlock
Date: Thu, 20 Sep 2018 10:36:20 +0300
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Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>,
        David Miller <davem@davemloft.net>,
        Stephen Hemminger <stephen@networkplumber.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>,
        Greg KH <gregkh@linuxfoundation.org>, mark.rutland@arm.com,
        Leon Romanovsky <leon@kernel.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Florian Westphal <fw@strlen.de>,
        David Ahern <dsahern@gmail.com>, christian@brauner.io,
        lucien xin <lucien.xin@gmail.com>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Jiri Benc <jbenc@redhat.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
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On Wed 19 Sep 2018 at 22:09, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Mon, Sep 17, 2018 at 12:19 AM Vlad Buslov <vladbu@mellanox.com> wrote:
>> @@ -482,16 +483,25 @@ static int tcf_block_insert(struct tcf_block *block, struct net *net,
>>                             struct netlink_ext_ack *extack)
>>  {
>>         struct tcf_net *tn = net_generic(net, tcf_net_id);
>> +       int err;
>> +
>> +       idr_preload(GFP_KERNEL);
>> +       spin_lock(&tn->idr_lock);
>> +       err = idr_alloc_u32(&tn->idr, block, &block->index, block->index,
>> +                           GFP_NOWAIT);
>
>
> Why GFP_NOWAIT rather than GFP_ATOMIC here?

I checked how idr_preload is used in kernel and in most places following
allocation uses GFP_NOWAIT (including idr-test.c). You suggest I should
change it to GFP_ATOMIC?