netdev - Re: [PATCH net-next v2 01/18] jump_label: export static_key_slow_{inc,dec}

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Message-ID: <1fdc9726-e21d-43f4-aee9-59276ddff37f@intel.com>
Date: Mon, 21 Oct 2024 15:53:40 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Toke Høiland-Jørgensen
	<toke@...hat.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
	<daniel@...earbox.net>, John Fastabend <john.fastabend@...il.com>, "Andrii
 Nakryiko" <andrii@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, "Magnus
 Karlsson" <magnus.karlsson@...el.com>,
	<nex.sw.ncis.osdt.itp.upstreaming@...el.com>, <bpf@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v2 01/18] jump_label: export
 static_key_slow_{inc,dec}_cpuslocked()

From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Date: Thu, 17 Oct 2024 13:06:25 +0200

> On Tue, Oct 15, 2024 at 04:53:33PM +0200, Alexander Lobakin wrote:
>> Sometimes, there's a need to modify a lot of static keys or modify the
>> same key multiple times in a loop. In that case, it seems more optimal
>> to lock cpu_read_lock once and then call _cpuslocked() variants.
>> The enable/disable functions are already exported, the refcounted
>> counterparts however are not. Fix that to allow modules to save some
>> cycles.
> 
> Hi Olek,
> 
> can you explain how is this at all related to the patchset that it
> contains? AFAIK I don't see it being used in later changes?

See libeth/xdp.c in patch #18, it's used to enable XDPSQ sharing static key.

> 
>>
>> Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
>> ---
>>  kernel/jump_label.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/kernel/jump_label.c b/kernel/jump_label.c
>> index 93a822d3c468..1034c0348995 100644
>> --- a/kernel/jump_label.c
>> +++ b/kernel/jump_label.c
>> @@ -182,6 +182,7 @@ bool static_key_slow_inc_cpuslocked(struct static_key *key)
>>  	}
>>  	return true;
>>  }
>> +EXPORT_SYMBOL_GPL(static_key_slow_inc_cpuslocked);
>>  
>>  bool static_key_slow_inc(struct static_key *key)
>>  {
>> @@ -342,6 +343,7 @@ void static_key_slow_dec_cpuslocked(struct static_key *key)
>>  	STATIC_KEY_CHECK_USE(key);
>>  	__static_key_slow_dec_cpuslocked(key);
>>  }
>> +EXPORT_SYMBOL_GPL(static_key_slow_dec_cpuslocked);
>>  
>>  void __static_key_slow_dec_deferred(struct static_key *key,
>>  				    struct delayed_work *work,
>> -- 
>> 2.46.2
>>

Thanks,
Olek