Subject: Re: [PATCH] llc: fix coding style and memory barrier documentation

From: kernel test robot <[email-masked]>
Date: Mon, 11 May 2026 07:57:45 +0800

Hi Lucas,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]
[also build test ERROR on net/main linus/master horms-ipvs/master v7.1-rc2 next-20260508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Lucas-Poupeau/llc-fix-coding-style-and-memory-barrier-documentation/20260510-102311
base:   net-next/main
patch link:    https://lore.kernel.org/r/20260505192549.74382-1-lucasp.linux%40gmail.com
patch subject: [PATCH] llc: fix coding style and memory barrier documentation
config: nios2-allmodconfig (https://download.01.org/0day-ci/archive/20260511/[email-masked]/config)
compiler: nios2-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260511/[email-masked]/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 <[email-masked]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/

All errors (new ones prefixed by >>):

   net/llc/llc_input.c: In function 'llc_rcv':
>> net/llc/llc_input.c:181:17: error: implicit declaration of function 'dprintk'; did you mean '_printk'? [-Werror=implicit-function-declaration]
     181 |                 dprintk("%s: PACKET_OTHERHOST\n", __func__);
         |                 ^~~~~~~
         |                 _printk
   cc1: some warnings being treated as errors

vim +181 net/llc/llc_input.c

^1da177e4c3f41 Linus Torvalds           2005-04-16  151  
^1da177e4c3f41 Linus Torvalds           2005-04-16  152  /**
^1da177e4c3f41 Linus Torvalds           2005-04-16  153   *	llc_rcv - 802.2 entry point from net lower layers
^1da177e4c3f41 Linus Torvalds           2005-04-16  154   *	@skb: received pdu
^1da177e4c3f41 Linus Torvalds           2005-04-16  155   *	@dev: device that receive pdu
^1da177e4c3f41 Linus Torvalds           2005-04-16  156   *	@pt: packet type
74c950c966c180 Andrew Lunn              2020-07-13  157   *	@orig_dev: the original receive net device
^1da177e4c3f41 Linus Torvalds           2005-04-16  158   *
^1da177e4c3f41 Linus Torvalds           2005-04-16  159   *	When the system receives a 802.2 frame this function is called. It
^1da177e4c3f41 Linus Torvalds           2005-04-16  160   *	checks SAP and connection of received pdu and passes frame to
^1da177e4c3f41 Linus Torvalds           2005-04-16  161   *	llc_{station,sap,conn}_rcv for sending to proper state machine. If
^1da177e4c3f41 Linus Torvalds           2005-04-16  162   *	the frame is related to a busy connection (a connection is sending
^1da177e4c3f41 Linus Torvalds           2005-04-16  163   *	data now), it queues this frame in the connection's backlog.
^1da177e4c3f41 Linus Torvalds           2005-04-16  164   */
^1da177e4c3f41 Linus Torvalds           2005-04-16  165  int llc_rcv(struct sk_buff *skb, struct net_device *dev,
f2ccd8fa06c8e3 David S. Miller          2005-08-09  166  	    struct packet_type *pt, struct net_device *orig_dev)
^1da177e4c3f41 Linus Torvalds           2005-04-16  167  {
^1da177e4c3f41 Linus Torvalds           2005-04-16  168  	struct llc_sap *sap;
^1da177e4c3f41 Linus Torvalds           2005-04-16  169  	struct llc_pdu_sn *pdu;
^1da177e4c3f41 Linus Torvalds           2005-04-16  170  	int dest;
846d7f9be89210 Lucas Poupeau            2026-05-05  171  	int (*rcv)(struct sk_buff *skb, struct net_device *dev,
846d7f9be89210 Lucas Poupeau            2026-05-05  172  		   struct packet_type *pt, struct net_device *orig_dev);
aadf31de16a7b2 Ben Hutchings            2012-08-13  173  	void (*sta_handler)(struct sk_buff *skb);
aadf31de16a7b2 Ben Hutchings            2012-08-13  174  	void (*sap_handler)(struct llc_sap *sap, struct sk_buff *skb);
^1da177e4c3f41 Linus Torvalds           2005-04-16  175  
^1da177e4c3f41 Linus Torvalds           2005-04-16  176  	/*
^1da177e4c3f41 Linus Torvalds           2005-04-16  177  	 * When the interface is in promisc. mode, drop all the crap that it
^1da177e4c3f41 Linus Torvalds           2005-04-16  178  	 * receives, do not try to analyse it.
^1da177e4c3f41 Linus Torvalds           2005-04-16  179  	 */
^1da177e4c3f41 Linus Torvalds           2005-04-16  180  	if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
0dc47877a3de00 Harvey Harrison          2008-03-05 @181  		dprintk("%s: PACKET_OTHERHOST\n", __func__);
^1da177e4c3f41 Linus Torvalds           2005-04-16  182  		goto drop;
^1da177e4c3f41 Linus Torvalds           2005-04-16  183  	}
^1da177e4c3f41 Linus Torvalds           2005-04-16  184  	skb = skb_share_check(skb, GFP_ATOMIC);
^1da177e4c3f41 Linus Torvalds           2005-04-16  185  	if (unlikely(!skb))
^1da177e4c3f41 Linus Torvalds           2005-04-16  186  		goto out;
^1da177e4c3f41 Linus Torvalds           2005-04-16  187  	if (unlikely(!llc_fixup_skb(skb)))
^1da177e4c3f41 Linus Torvalds           2005-04-16  188  		goto drop;
^1da177e4c3f41 Linus Torvalds           2005-04-16  189  	pdu = llc_pdu_sn_hdr(skb);
^1da177e4c3f41 Linus Torvalds           2005-04-16  190  	if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
^1da177e4c3f41 Linus Torvalds           2005-04-16  191  	       goto handle_station;
^1da177e4c3f41 Linus Torvalds           2005-04-16  192  	sap = llc_sap_find(pdu->dsap);
^1da177e4c3f41 Linus Torvalds           2005-04-16  193  	if (unlikely(!sap)) {/* unknown SAP */
0dc47877a3de00 Harvey Harrison          2008-03-05  194  		dprintk("%s: llc_sap_find(%02X) failed!\n", __func__,
^1da177e4c3f41 Linus Torvalds           2005-04-16  195  			pdu->dsap);
^1da177e4c3f41 Linus Torvalds           2005-04-16  196  		goto drop;
^1da177e4c3f41 Linus Torvalds           2005-04-16  197  	}
^1da177e4c3f41 Linus Torvalds           2005-04-16  198  	/*
^1da177e4c3f41 Linus Torvalds           2005-04-16  199  	 * First the upper layer protocols that don't need the full
^1da177e4c3f41 Linus Torvalds           2005-04-16  200  	 * LLC functionality
^1da177e4c3f41 Linus Torvalds           2005-04-16  201  	 */
23dbe7912dad6b Stephen Hemminger        2006-05-25  202  	rcv = rcu_dereference(sap->rcv_func);
696ea472e19c6d Changli Gao              2011-02-22  203  	dest = llc_pdu_type(skb);
6aa7de059173a9 Mark Rutland             2017-10-23  204  	sap_handler = dest ? READ_ONCE(llc_type_handlers[dest - 1]) : NULL;
aadf31de16a7b2 Ben Hutchings            2012-08-13  205  	if (unlikely(!sap_handler)) {
696ea472e19c6d Changli Gao              2011-02-22  206  		if (rcv)
696ea472e19c6d Changli Gao              2011-02-22  207  			rcv(skb, dev, pt, orig_dev);
696ea472e19c6d Changli Gao              2011-02-22  208  		else
696ea472e19c6d Changli Gao              2011-02-22  209  			kfree_skb(skb);
696ea472e19c6d Changli Gao              2011-02-22  210  	} else {
23dbe7912dad6b Stephen Hemminger        2006-05-25  211  		if (rcv) {
8f182b494f8779 Stephen Hemminger        2006-05-25  212  			struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
846d7f9be89210 Lucas Poupeau            2026-05-05  213  
8f182b494f8779 Stephen Hemminger        2006-05-25  214  			if (cskb)
8f182b494f8779 Stephen Hemminger        2006-05-25  215  				rcv(cskb, dev, pt, orig_dev);
^1da177e4c3f41 Linus Torvalds           2005-04-16  216  		}
aadf31de16a7b2 Ben Hutchings            2012-08-13  217  		sap_handler(sap, skb);
696ea472e19c6d Changli Gao              2011-02-22  218  	}
6e2144b76840be Arnaldo Carvalho de Melo 2005-09-22  219  	llc_sap_put(sap);
^1da177e4c3f41 Linus Torvalds           2005-04-16  220  out:
^1da177e4c3f41 Linus Torvalds           2005-04-16  221  	return 0;
^1da177e4c3f41 Linus Torvalds           2005-04-16  222  drop:
^1da177e4c3f41 Linus Torvalds           2005-04-16  223  	kfree_skb(skb);
^1da177e4c3f41 Linus Torvalds           2005-04-16  224  	goto out;
846d7f9be89210 Lucas Poupeau            2026-05-05  225  
^1da177e4c3f41 Linus Torvalds           2005-04-16  226  handle_station:
6aa7de059173a9 Mark Rutland             2017-10-23  227  	sta_handler = READ_ONCE(llc_station_handler);
aadf31de16a7b2 Ben Hutchings            2012-08-13  228  	if (!sta_handler)
^1da177e4c3f41 Linus Torvalds           2005-04-16  229  		goto drop;
aadf31de16a7b2 Ben Hutchings            2012-08-13  230  	sta_handler(skb);
^1da177e4c3f41 Linus Torvalds           2005-04-16  231  	goto out;
^1da177e4c3f41 Linus Torvalds           2005-04-16  232  }
^1da177e4c3f41 Linus Torvalds           2005-04-16  233  

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