tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git 
dev.2020.07.14a
head:   aace6daf32cce6b644083754c7be6260aae439db
commit: 93d62a873f87bf69209a5c29d62b9497888de6d6 [64/73] kvm: mmu: page_track: 
Fix RCU list API usage
config: i386-randconfig-a006-20200726 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-14) 9.3.0
reproduce (this is a W=1 build):
        git checkout 93d62a873f87bf69209a5c29d62b9497888de6d6
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>

Note: the rcu/dev.2020.07.14a HEAD aace6daf32cce6b644083754c7be6260aae439db 
builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   In file included from include/linux/pid.h:5,
                    from include/linux/sched.h:14,
                    from include/linux/kvm_host.h:12,
                    from arch/x86/kvm/mmu/page_track.c:14:
   arch/x86/kvm/mmu/page_track.c: In function 'kvm_page_track_write':
>> include/linux/rculist.h:727:30: error: left-hand operand of comma expression 
>> has no effect [-Werror=unused-value]
     727 |  for (__list_check_srcu(cond),     \
         |                              ^
   arch/x86/kvm/mmu/page_track.c:232:2: note: in expansion of macro 
'hlist_for_each_entry_srcu'
     232 |  hlist_for_each_entry_srcu(n, &head->track_notifier_list, node,
         |  ^~~~~~~~~~~~~~~~~~~~~~~~~
   arch/x86/kvm/mmu/page_track.c: In function 'kvm_page_track_flush_slot':
>> include/linux/rculist.h:727:30: error: left-hand operand of comma expression 
>> has no effect [-Werror=unused-value]
     727 |  for (__list_check_srcu(cond),     \
         |                              ^
   arch/x86/kvm/mmu/page_track.c:258:2: note: in expansion of macro 
'hlist_for_each_entry_srcu'
     258 |  hlist_for_each_entry_srcu(n, &head->track_notifier_list, node,
         |  ^~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors

vim +727 include/linux/rculist.h

82524746c27fa41 Franck Bui-Huu          2008-05-12  688  
1cc523271ef0b63 stephen hemminger       2010-02-22  689  #define 
__hlist_for_each_rcu(pos, head)                                \
67bdbffd696f29a Arnd Bergmann           2010-02-25  690         for (pos = 
rcu_dereference(hlist_first_rcu(head));      \
75d65a425c0163d Linus Torvalds          2011-05-19  691              pos;       
                                        \
67bdbffd696f29a Arnd Bergmann           2010-02-25  692              pos = 
rcu_dereference(hlist_next_rcu(pos)))
1cc523271ef0b63 stephen hemminger       2010-02-22  693  
82524746c27fa41 Franck Bui-Huu          2008-05-12  694  /**
82524746c27fa41 Franck Bui-Huu          2008-05-12  695   * 
hlist_for_each_entry_rcu - iterate over rcu list of given type
b67bfe0d42cac56 Sasha Levin             2013-02-27  696   * @pos:       the 
type * to use as a loop cursor.
82524746c27fa41 Franck Bui-Huu          2008-05-12  697   * @head:      the 
head for your list.
82524746c27fa41 Franck Bui-Huu          2008-05-12  698   * @member:    the 
name of the hlist_node within the struct.
ddc465936643108 Jonathan Neuschäfer     2020-03-05  699   * @cond:      
optional lockdep expression if called from non-RCU protection.
82524746c27fa41 Franck Bui-Huu          2008-05-12  700   *
82524746c27fa41 Franck Bui-Huu          2008-05-12  701   * This list-traversal 
primitive may safely run concurrently with
82524746c27fa41 Franck Bui-Huu          2008-05-12  702   * the _rcu 
list-mutation primitives such as hlist_add_head_rcu()
82524746c27fa41 Franck Bui-Huu          2008-05-12  703   * as long as the 
traversal is guarded by rcu_read_lock().
82524746c27fa41 Franck Bui-Huu          2008-05-12  704   */
28875945ba98d1b Joel Fernandes (Google  2019-07-16  705) #define 
hlist_for_each_entry_rcu(pos, head, member, cond...)           \
28875945ba98d1b Joel Fernandes (Google  2019-07-16  706)        for 
(__list_check_rcu(dummy, ## cond, 0),                       \
28875945ba98d1b Joel Fernandes (Google  2019-07-16  707)             pos = 
hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
b67bfe0d42cac56 Sasha Levin             2013-02-27  708                         
typeof(*(pos)), member);                        \
b67bfe0d42cac56 Sasha Levin             2013-02-27  709                 pos;    
                                                \
b67bfe0d42cac56 Sasha Levin             2013-02-27  710                 pos = 
hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  711                         
&(pos)->member)), typeof(*(pos)), member))
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  712  
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  713  /**
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  714   * 
hlist_for_each_entry_srcu - iterate over rcu list of given type
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  715   * @pos:       the 
type * to use as a loop cursor.
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  716   * @head:      the 
head for your list.
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  717   * @member:    the 
name of the hlist_node within the struct.
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  718   * @cond:      lockdep 
expression for the lock required to traverse the list.
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  719   *
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  720   * This list-traversal 
primitive may safely run concurrently with
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  721   * the _rcu 
list-mutation primitives such as hlist_add_head_rcu()
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  722   * as long as the 
traversal is guarded by srcu_read_lock().
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  723   * The lockdep 
expression srcu_read_lock_held() can be passed as the
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  724   * cond argument from 
read side.
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  725   */
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  726  #define 
hlist_for_each_entry_srcu(pos, head, member, cond)             \
bd4444c47de914a Madhuparna Bhowmik      2020-07-12 @727         for 
(__list_check_srcu(cond),                                   \
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  728              pos = 
hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  729                         
typeof(*(pos)), member);                        \
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  730                 pos;    
                                                \
bd4444c47de914a Madhuparna Bhowmik      2020-07-12  731                 pos = 
hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
b67bfe0d42cac56 Sasha Levin             2013-02-27  732                         
&(pos)->member)), typeof(*(pos)), member))
82524746c27fa41 Franck Bui-Huu          2008-05-12  733  

:::::: The code at line 727 was first introduced by commit
:::::: bd4444c47de914a27b650f029d46efbbb6809765 rculist : Introduce 
list/hlist_for_each_entry_srcu() macros

:::::: TO: Madhuparna Bhowmik <madhuparnabhowmi...@gmail.com>
:::::: CC: Paul E. McKenney <paul...@kernel.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org

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