Subject: Re: [PATCH] net: neterion: vxge: reduce stack usage in VXGE_COMPLETE_VPATH_TX

From: kernel test robot <[email-masked]>
Date: Thu, 16 Jul 2020 19:20:10 +0800

Hi Bixuan,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on sparc-next/master]
[also build test WARNING on net-next/master net/master linus/master v5.8-rc5 next-20200716]
[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]

url:    https://github.com/0day-ci/linux/commits/Bixuan-Cui/net-neterion-vxge-reduce-stack-usage-in-VXGE_COMPLETE_VPATH_TX/20200716-173219
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next.git master
config: s390-allyesconfig (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=s390 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email-masked]>

All warnings (new ones prefixed by >>):

      91 | #define this_cpu_add_8(pcp, val) arch_this_cpu_add(pcp, val, "laag", "agsi", long)
         |                                  ^~~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:380:11: note: in expansion of macro 'this_cpu_add_8'
     380 |   case 8: stem##8(variable, __VA_ARGS__);break;  \
         |           ^~~~
   include/linux/percpu-defs.h:509:33: note: in expansion of macro '__pcpu_size_call'
     509 | #define this_cpu_add(pcp, val)  __pcpu_size_call(this_cpu_add_, pcp, val)
         |                                 ^~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:519:33: note: in expansion of macro 'this_cpu_add'
     519 | #define this_cpu_sub(pcp, val)  this_cpu_add(pcp, -(typeof(pcp))(val))
         |                                 ^~~~~~~~~~~~
   include/linux/percpu-defs.h:521:28: note: in expansion of macro 'this_cpu_sub'
     521 | #define this_cpu_dec(pcp)  this_cpu_sub(pcp, 1)
         |                            ^~~~~~~~~~~~
   include/net/sch_generic.h:872:2: note: in expansion of macro 'this_cpu_dec'
     872 |  this_cpu_dec(sch->cpu_qstats->qlen);
         |  ^~~~~~~~~~~~
   include/net/sch_generic.h: In function 'qdisc_qstats_cpu_requeues_inc':
   arch/s390/include/asm/percpu.h:74:21: warning: comparison is always true due to limited range of data type [-Wtype-limits]
      74 |      ((szcast)val__ > -129) && ((szcast)val__ < 128)) {  \
         |                     ^
   arch/s390/include/asm/percpu.h:91:34: note: in expansion of macro 'arch_this_cpu_add'
      91 | #define this_cpu_add_8(pcp, val) arch_this_cpu_add(pcp, val, "laag", "agsi", long)
         |                                  ^~~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:380:11: note: in expansion of macro 'this_cpu_add_8'
     380 |   case 8: stem##8(variable, __VA_ARGS__);break;  \
         |           ^~~~
   include/linux/percpu-defs.h:509:33: note: in expansion of macro '__pcpu_size_call'
     509 | #define this_cpu_add(pcp, val)  __pcpu_size_call(this_cpu_add_, pcp, val)
         |                                 ^~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:520:28: note: in expansion of macro 'this_cpu_add'
     520 | #define this_cpu_inc(pcp)  this_cpu_add(pcp, 1)
         |                            ^~~~~~~~~~~~
   include/net/sch_generic.h:877:2: note: in expansion of macro 'this_cpu_inc'
     877 |  this_cpu_inc(sch->cpu_qstats->requeues);
         |  ^~~~~~~~~~~~
   include/net/sch_generic.h: In function 'qdisc_qstats_cpu_drop':
   arch/s390/include/asm/percpu.h:74:21: warning: comparison is always true due to limited range of data type [-Wtype-limits]
      74 |      ((szcast)val__ > -129) && ((szcast)val__ < 128)) {  \
         |                     ^
   arch/s390/include/asm/percpu.h:91:34: note: in expansion of macro 'arch_this_cpu_add'
      91 | #define this_cpu_add_8(pcp, val) arch_this_cpu_add(pcp, val, "laag", "agsi", long)
         |                                  ^~~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:380:11: note: in expansion of macro 'this_cpu_add_8'
     380 |   case 8: stem##8(variable, __VA_ARGS__);break;  \
         |           ^~~~
   include/linux/percpu-defs.h:509:33: note: in expansion of macro '__pcpu_size_call'
     509 | #define this_cpu_add(pcp, val)  __pcpu_size_call(this_cpu_add_, pcp, val)
         |                                 ^~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:520:28: note: in expansion of macro 'this_cpu_add'
     520 | #define this_cpu_inc(pcp)  this_cpu_add(pcp, 1)
         |                            ^~~~~~~~~~~~
   include/net/sch_generic.h:902:2: note: in expansion of macro 'this_cpu_inc'
     902 |  this_cpu_inc(sch->cpu_qstats->drops);
         |  ^~~~~~~~~~~~
   include/net/sch_generic.h: In function 'qdisc_update_stats_at_enqueue':
   arch/s390/include/asm/percpu.h:74:21: warning: comparison is always true due to limited range of data type [-Wtype-limits]
      74 |      ((szcast)val__ > -129) && ((szcast)val__ < 128)) {  \
         |                     ^
   arch/s390/include/asm/percpu.h:91:34: note: in expansion of macro 'arch_this_cpu_add'
      91 | #define this_cpu_add_8(pcp, val) arch_this_cpu_add(pcp, val, "laag", "agsi", long)
         |                                  ^~~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:380:11: note: in expansion of macro 'this_cpu_add_8'
     380 |   case 8: stem##8(variable, __VA_ARGS__);break;  \
         |           ^~~~
   include/linux/percpu-defs.h:509:33: note: in expansion of macro '__pcpu_size_call'
     509 | #define this_cpu_add(pcp, val)  __pcpu_size_call(this_cpu_add_, pcp, val)
         |                                 ^~~~~~~~~~~~~~~~
   include/net/sch_generic.h:1101:3: note: in expansion of macro 'this_cpu_add'
    1101 |   this_cpu_add(sch->cpu_qstats->backlog, pkt_len);
         |   ^~~~~~~~~~~~
   include/net/sch_generic.h: In function 'mini_qdisc_qstats_cpu_drop':
   arch/s390/include/asm/percpu.h:74:21: warning: comparison is always true due to limited range of data type [-Wtype-limits]
      74 |      ((szcast)val__ > -129) && ((szcast)val__ < 128)) {  \
         |                     ^
   arch/s390/include/asm/percpu.h:91:34: note: in expansion of macro 'arch_this_cpu_add'
      91 | #define this_cpu_add_8(pcp, val) arch_this_cpu_add(pcp, val, "laag", "agsi", long)
         |                                  ^~~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:380:11: note: in expansion of macro 'this_cpu_add_8'
     380 |   case 8: stem##8(variable, __VA_ARGS__);break;  \
         |           ^~~~
   include/linux/percpu-defs.h:509:33: note: in expansion of macro '__pcpu_size_call'
     509 | #define this_cpu_add(pcp, val)  __pcpu_size_call(this_cpu_add_, pcp, val)
         |                                 ^~~~~~~~~~~~~~~~
   include/linux/percpu-defs.h:520:28: note: in expansion of macro 'this_cpu_add'
     520 | #define this_cpu_inc(pcp)  this_cpu_add(pcp, 1)
         |                            ^~~~~~~~~~~~
   include/net/sch_generic.h:1270:2: note: in expansion of macro 'this_cpu_inc'
    1270 |  this_cpu_inc(miniq->cpu_qstats->drops);
         |  ^~~~~~~~~~~~
   drivers/net/ethernet/neterion/vxge/vxge-main.c: In function 'VXGE_COMPLETE_VPATH_TX':
   drivers/net/ethernet/neterion/vxge/vxge-main.c:103:19: error: conflicting types for 'completed'
     103 |  struct sk_buff **completed;
         |                   ^~~~~~~~~
   drivers/net/ethernet/neterion/vxge/vxge-main.c:102:18: note: previous declaration of 'completed' was here
     102 |  struct sk_buff *completed[NR_SKB_COMPLETED];
         |                  ^~~~~~~~~
   drivers/net/ethernet/neterion/vxge/vxge-main.c:126:2: error: implicit declaration of function 'free' [-Werror=implicit-function-declaration]
     126 |  free(completed);
         |  ^~~~
>> drivers/net/ethernet/neterion/vxge/vxge-main.c:126:2: warning: incompatible implicit declaration of built-in function 'free'
   drivers/net/ethernet/neterion/vxge/vxge-main.c:60:1: note: include '<stdlib.h>' or provide a declaration of 'free'
      59 | #include "vxge-main.h"
     +++ |+#include <stdlib.h>
      60 | #include "vxge-reg.h"
   cc1: some warnings being treated as errors

vim +/free +126 drivers/net/ethernet/neterion/vxge/vxge-main.c

    96	
    97	static inline void VXGE_COMPLETE_VPATH_TX(struct vxge_fifo *fifo)
    98	{
    99		struct sk_buff **skb_ptr = NULL;
   100		struct sk_buff **temp;
   101	#define NR_SKB_COMPLETED 128
   102		struct sk_buff *completed[NR_SKB_COMPLETED];
   103		struct sk_buff **completed;
   104		int more;
   105	
   106		completed = kcalloc(NR_SKB_COMPLETED, sizeof(*completed),
   107				    GFP_KERNEL);
   108		if (!completed)
   109			return;
   110	
   111		do {
   112			more = 0;
   113			skb_ptr = completed;
   114	
   115			if (__netif_tx_trylock(fifo->txq)) {
   116				vxge_hw_vpath_poll_tx(fifo->handle, &skb_ptr,
   117							NR_SKB_COMPLETED, &more);
   118				__netif_tx_unlock(fifo->txq);
   119			}
   120	
   121			/* free SKBs */
   122			for (temp = completed; temp != skb_ptr; temp++)
   123				dev_consume_skb_irq(*temp);
   124		} while (more);
   125	
 > 126		free(completed);
   127	}
   128	

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