netdev - Re: [PATCH v8 bpf] xsk: fix immature cq descriptor production

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Message-ID: <07646dce-dab4-4afe-a09a-e6a83502ac30@intel.com>
Date: Thu, 4 Sep 2025 13:31:10 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
CC: kernel test robot <lkp@...el.com>, <bpf@...r.kernel.org>,
	<ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
	<oe-kbuild-all@...ts.linux.dev>, <netdev@...r.kernel.org>,
	<magnus.karlsson@...el.com>, <stfomichev@...il.com>,
	<kerneljasonxing@...il.com>, Eryk Kubanski <e.kubanski@...tner.samsung.com>,
	Stanislav Fomichev <sdf@...ichev.me>
Subject: Re: [PATCH v8 bpf] xsk: fix immature cq descriptor production

From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Date: Thu, 4 Sep 2025 11:31:44 +0200

> On Wed, Sep 03, 2025 at 10:29:02AM +0800, kernel test robot wrote:
>> Hi Maciej,
>>
>> kernel test robot noticed the following build warnings:
>>
>> [auto build test WARNING on bpf/master]
>>
>> url:    https://github.com/intel-lab-lkp/linux/commits/Maciej-Fijalkowski/xsk-fix-immature-cq-descriptor-production/20250903-060850
>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
>> patch link:    https://lore.kernel.org/r/20250902220613.2331265-1-maciej.fijalkowski%40intel.com
>> patch subject: [PATCH v8 bpf] xsk: fix immature cq descriptor production
>> config: riscv-randconfig-001-20250903 (https://download.01.org/0day-ci/archive/20250903/202509031029.iL7rCVvQ-lkp@intel.com/config)
>> compiler: riscv32-linux-gcc (GCC) 8.5.0
>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250903/202509031029.iL7rCVvQ-lkp@intel.com/reproduce)
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <lkp@...el.com>
>> | Closes: https://lore.kernel.org/oe-kbuild-all/202509031029.iL7rCVvQ-lkp@intel.com/
>>
>> All warnings (new ones prefixed by >>):
>>
>>    net/xdp/xsk.c: In function 'xsk_cq_submit_addr_locked':
>>>> net/xdp/xsk.c:572:38: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
>>      xskq_prod_write_addr(pool->cq, idx, (u64)skb_shinfo(skb)->destructor_arg);
>>                                          ^
>>    net/xdp/xsk.c: In function 'xsk_set_destructor_arg':
>>>> net/xdp/xsk.c:625:36: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
>>      skb_shinfo(skb)->destructor_arg = (void *)addr;
> 
> Meh, I suppose uintptr_t casting will help here.

Correct, you need a double cast to convert u64 <-> void *, see [0].

Maybe we'd want to make those helpers generic in future...

> So I'll send v9 in the evening :)

[0]
https://elixir.bootlin.com/linux/v6.17-rc4/source/include/net/libeth/xdp.h#L475

Thanks,
Olek