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Date: Fri, 15 Jul 2022 00:21:30 +0800
From: kernel test robot <lkp@...el.com>
To: Nicholas Piggin <npiggin@...il.com>
Cc: llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
Nicholas Piggin <npiggin@...il.com>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Waiman Long <longman@...hat.com>,
Boqun Feng <boqun.feng@...il.com>,
"linux-kernel @ vger . kernel . org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 07/12] locking/qspinlock: remove arch
qspinlock_paravirt.h includes
Hi Nicholas,
I love your patch! Perhaps something to improve:
[auto build test WARNING on tip/locking/core]
[also build test WARNING on tip/x86/core powerpc/next linus/master v5.19-rc6 next-20220714]
[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/Nicholas-Piggin/locking-qspinlock-simplify-code-generation/20220713-151009
base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git eae6d58d67d9739be5f7ae2dbead1d0ef6528243
config: i386-randconfig-a004 (https://download.01.org/0day-ci/archive/20220715/202207150003.29YhgBtE-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 5e61b9c556267086ef9b743a0b57df302eef831b)
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
# https://github.com/intel-lab-lkp/linux/commit/87679eeea9f1939c252d16df3ac6a01bf9daaa60
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Nicholas-Piggin/locking-qspinlock-simplify-code-generation/20220713-151009
git checkout 87679eeea9f1939c252d16df3ac6a01bf9daaa60
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/locking/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>
All warnings (new ones prefixed by >>):
In file included from kernel/locking/qspinlock.c:29:
kernel/locking/qspinlock_stat.h:36:9: warning: no previous prototype for function 'lockevent_read' [-Wmissing-prototypes]
ssize_t lockevent_read(struct file *file, char __user *user_buf,
^
kernel/locking/qspinlock_stat.h:36:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
ssize_t lockevent_read(struct file *file, char __user *user_buf,
^
static
kernel/locking/qspinlock.c:705:1: warning: no previous prototype for function '__pv_queued_spin_unlock_slowpath' [-Wmissing-prototypes]
__pv_queued_spin_unlock_slowpath(struct qspinlock *lock, u8 locked)
^
kernel/locking/qspinlock.c:704:11: note: declare 'static' if the function is not intended to be used outside of this translation unit
__visible void
^
static
>> kernel/locking/qspinlock.c:749:16: warning: no previous prototype for function '__pv_queued_spin_unlock' [-Wmissing-prototypes]
__visible void __pv_queued_spin_unlock(struct qspinlock *lock)
^
kernel/locking/qspinlock.c:749:11: note: declare 'static' if the function is not intended to be used outside of this translation unit
__visible void __pv_queued_spin_unlock(struct qspinlock *lock)
^
static
3 warnings generated.
vim +/__pv_queued_spin_unlock +749 kernel/locking/qspinlock.c
91668ee1ed703d7 Nicholas Piggin 2022-07-13 699
91668ee1ed703d7 Nicholas Piggin 2022-07-13 700 /*
91668ee1ed703d7 Nicholas Piggin 2022-07-13 701 * PV versions of the unlock fastpath and slowpath functions to be used
91668ee1ed703d7 Nicholas Piggin 2022-07-13 702 * instead of queued_spin_unlock().
91668ee1ed703d7 Nicholas Piggin 2022-07-13 703 */
91668ee1ed703d7 Nicholas Piggin 2022-07-13 704 __visible void
91668ee1ed703d7 Nicholas Piggin 2022-07-13 @705 __pv_queued_spin_unlock_slowpath(struct qspinlock *lock, u8 locked)
91668ee1ed703d7 Nicholas Piggin 2022-07-13 706 {
91668ee1ed703d7 Nicholas Piggin 2022-07-13 707 struct qnode *node;
91668ee1ed703d7 Nicholas Piggin 2022-07-13 708
91668ee1ed703d7 Nicholas Piggin 2022-07-13 709 if (unlikely(locked != _Q_SLOW_VAL)) {
91668ee1ed703d7 Nicholas Piggin 2022-07-13 710 WARN(!debug_locks_silent,
91668ee1ed703d7 Nicholas Piggin 2022-07-13 711 "pvqspinlock: lock 0x%lx has corrupted value 0x%x!\n",
91668ee1ed703d7 Nicholas Piggin 2022-07-13 712 (unsigned long)lock, atomic_read(&lock->val));
91668ee1ed703d7 Nicholas Piggin 2022-07-13 713 return;
91668ee1ed703d7 Nicholas Piggin 2022-07-13 714 }
91668ee1ed703d7 Nicholas Piggin 2022-07-13 715
91668ee1ed703d7 Nicholas Piggin 2022-07-13 716 /*
91668ee1ed703d7 Nicholas Piggin 2022-07-13 717 * A failed cmpxchg doesn't provide any memory-ordering guarantees,
91668ee1ed703d7 Nicholas Piggin 2022-07-13 718 * so we need a barrier to order the read of the node data in
91668ee1ed703d7 Nicholas Piggin 2022-07-13 719 * pv_unhash *after* we've read the lock being _Q_SLOW_VAL.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 720 *
91668ee1ed703d7 Nicholas Piggin 2022-07-13 721 * Matches the cmpxchg() in pv_wait_head_or_lock() setting _Q_SLOW_VAL.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 722 */
91668ee1ed703d7 Nicholas Piggin 2022-07-13 723 smp_rmb();
91668ee1ed703d7 Nicholas Piggin 2022-07-13 724
91668ee1ed703d7 Nicholas Piggin 2022-07-13 725 /*
91668ee1ed703d7 Nicholas Piggin 2022-07-13 726 * Since the above failed to release, this must be the SLOW path.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 727 * Therefore start by looking up the blocked node and unhashing it.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 728 */
91668ee1ed703d7 Nicholas Piggin 2022-07-13 729 node = pv_unhash(lock);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 730
91668ee1ed703d7 Nicholas Piggin 2022-07-13 731 /*
91668ee1ed703d7 Nicholas Piggin 2022-07-13 732 * Now that we have a reference to the (likely) blocked qnode,
91668ee1ed703d7 Nicholas Piggin 2022-07-13 733 * release the lock.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 734 */
91668ee1ed703d7 Nicholas Piggin 2022-07-13 735 smp_store_release(&lock->locked, 0);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 736
91668ee1ed703d7 Nicholas Piggin 2022-07-13 737 /*
91668ee1ed703d7 Nicholas Piggin 2022-07-13 738 * At this point the memory pointed at by lock can be freed/reused,
91668ee1ed703d7 Nicholas Piggin 2022-07-13 739 * however we can still use the qnode to kick the CPU.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 740 * The other vCPU may not really be halted, but kicking an active
91668ee1ed703d7 Nicholas Piggin 2022-07-13 741 * vCPU is harmless other than the additional latency in completing
91668ee1ed703d7 Nicholas Piggin 2022-07-13 742 * the unlock.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 743 */
91668ee1ed703d7 Nicholas Piggin 2022-07-13 744 lockevent_inc(pv_kick_unlock);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 745 pv_kick(node->cpu);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 746 }
91668ee1ed703d7 Nicholas Piggin 2022-07-13 747
91668ee1ed703d7 Nicholas Piggin 2022-07-13 748 #ifndef __pv_queued_spin_unlock
91668ee1ed703d7 Nicholas Piggin 2022-07-13 @749 __visible void __pv_queued_spin_unlock(struct qspinlock *lock)
91668ee1ed703d7 Nicholas Piggin 2022-07-13 750 {
91668ee1ed703d7 Nicholas Piggin 2022-07-13 751 u8 locked;
91668ee1ed703d7 Nicholas Piggin 2022-07-13 752
91668ee1ed703d7 Nicholas Piggin 2022-07-13 753 /*
91668ee1ed703d7 Nicholas Piggin 2022-07-13 754 * We must not unlock if SLOW, because in that case we must first
91668ee1ed703d7 Nicholas Piggin 2022-07-13 755 * unhash. Otherwise it would be possible to have multiple @lock
91668ee1ed703d7 Nicholas Piggin 2022-07-13 756 * entries, which would be BAD.
91668ee1ed703d7 Nicholas Piggin 2022-07-13 757 */
91668ee1ed703d7 Nicholas Piggin 2022-07-13 758 locked = cmpxchg_release(&lock->locked, _Q_LOCKED_VAL, 0);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 759 if (likely(locked == _Q_LOCKED_VAL))
91668ee1ed703d7 Nicholas Piggin 2022-07-13 760 return;
91668ee1ed703d7 Nicholas Piggin 2022-07-13 761
91668ee1ed703d7 Nicholas Piggin 2022-07-13 762 __pv_queued_spin_unlock_slowpath(lock, locked);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 763 }
87679eeea9f1939 Nicholas Piggin 2022-07-13 764 EXPORT_SYMBOL(__pv_queued_spin_unlock);
91668ee1ed703d7 Nicholas Piggin 2022-07-13 765 #endif
91668ee1ed703d7 Nicholas Piggin 2022-07-13 766
--
0-DAY CI Kernel Test Service
https://01.org/lkp
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