[rcu:dev.2020.07.14a 64/73] include/linux/rculist.h:727:30: error: left-hand operand of comma expression has no effect
From: kernel test robot
Date: Sat Jul 25 2020 - 23:47:32 EST
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 <lkp@xxxxxxxxx>
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 <madhuparnabhowmik10@xxxxxxxxx>
:::::: CC: Paul E. McKenney <paulmck@xxxxxxxxxx>
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