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

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Message-ID: <aLlcgDC7s3Dh0NdX@boxer>
Date: Thu, 4 Sep 2025 11:31:44 +0200
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: kernel test robot <lkp@...el.com>
CC: <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

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

>                                        ^
> 
> 
> vim +572 net/xdp/xsk.c
> 
>    560	
>    561	static void xsk_cq_submit_addr_locked(struct xsk_buff_pool *pool,
>    562					      struct sk_buff *skb)
>    563	{
>    564		struct xsk_addr_node *pos, *tmp;
>    565		u32 descs_processed = 0;
>    566		unsigned long flags;
>    567		u32 idx;
>    568	
>    569		spin_lock_irqsave(&pool->cq_lock, flags);
>    570		idx = xskq_get_prod(pool->cq);
>    571	
>  > 572		xskq_prod_write_addr(pool->cq, idx, (u64)skb_shinfo(skb)->destructor_arg);
>    573		descs_processed++;
>    574	
>    575		if (unlikely(XSKCB(skb)->num_descs > 1)) {
>    576			list_for_each_entry_safe(pos, tmp, &XSKCB(skb)->addrs_list, addr_node) {
>    577				xskq_prod_write_addr(pool->cq, idx + descs_processed,
>    578						     pos->addr);
>    579				descs_processed++;
>    580				list_del(&pos->addr_node);
>    581				kmem_cache_free(xsk_tx_generic_cache, pos);
>    582			}
>    583		}
>    584		xskq_prod_submit_n(pool->cq, descs_processed);
>    585		spin_unlock_irqrestore(&pool->cq_lock, flags);
>    586	}
>    587	
>    588	static void xsk_cq_cancel_locked(struct xsk_buff_pool *pool, u32 n)
>    589	{
>    590		unsigned long flags;
>    591	
>    592		spin_lock_irqsave(&pool->cq_lock, flags);
>    593		xskq_prod_cancel_n(pool->cq, n);
>    594		spin_unlock_irqrestore(&pool->cq_lock, flags);
>    595	}
>    596	
>    597	static void xsk_inc_num_desc(struct sk_buff *skb)
>    598	{
>    599		XSKCB(skb)->num_descs++;
>    600	}
>    601	
>    602	static u32 xsk_get_num_desc(struct sk_buff *skb)
>    603	{
>    604		return XSKCB(skb)->num_descs;
>    605	}
>    606	
>    607	static void xsk_destruct_skb(struct sk_buff *skb)
>    608	{
>    609		struct xsk_tx_metadata_compl *compl = &skb_shinfo(skb)->xsk_meta;
>    610	
>    611		if (compl->tx_timestamp) {
>    612			/* sw completion timestamp, not a real one */
>    613			*compl->tx_timestamp = ktime_get_tai_fast_ns();
>    614		}
>    615	
>    616		xsk_cq_submit_addr_locked(xdp_sk(skb->sk)->pool, skb);
>    617		sock_wfree(skb);
>    618	}
>    619	
>    620	static void xsk_set_destructor_arg(struct sk_buff *skb, u64 addr)
>    621	{
>    622		BUILD_BUG_ON(sizeof(struct xsk_addr_head) > sizeof(skb->cb));
>    623		INIT_LIST_HEAD(&XSKCB(skb)->addrs_list);
>    624		XSKCB(skb)->num_descs = 0;
>  > 625		skb_shinfo(skb)->destructor_arg = (void *)addr;
>    626	}
>    627	
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki