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From: Waiman Long <longman@redhat.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Ben Gardon <bgardon@google.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Peter Shier <pshier@google.com>,
	Peter Feiner <pfeiner@google.com>,
	Junaid Shahid <junaids@google.com>,
	Jim Mattson <jmattson@google.com>,
	Yulei Zhang <yulei.kernel@gmail.com>,
	Wanpeng Li <kernellwp@gmail.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH v2 06/28] locking/rwlocks: Add contention detection for rwlocks
Date: Tue, 9 Feb 2021 19:41:41 -0500	[thread overview]
Message-ID: <6fef33ce-f470-255b-0872-cc9dd057e857@redhat.com> (raw)
In-Reply-To: <fc7792e2-26f1-2b37-fb79-002d8d6d4ef7@redhat.com>

On 2/9/21 7:27 PM, Waiman Long wrote:
> On 2/9/21 5:25 PM, Guenter Roeck wrote:
>> On Tue, Feb 09, 2021 at 04:46:02PM -0500, Waiman Long wrote:
>>> On 2/9/21 3:39 PM, Guenter Roeck wrote:
>>>> On Tue, Feb 02, 2021 at 10:57:12AM -0800, Ben Gardon wrote:
>>>>> rwlocks do not currently have any facility to detect contention
>>>>> like spinlocks do. In order to allow users of rwlocks to better 
>>>>> manage
>>>>> latency, add contention detection for queued rwlocks.
>>>>>
>>>>> CC: Ingo Molnar <mingo@redhat.com>
>>>>> CC: Will Deacon <will@kernel.org>
>>>>> Acked-by: Peter Zijlstra <peterz@infradead.org>
>>>>> Acked-by: Davidlohr Bueso <dbueso@suse.de>
>>>>> Acked-by: Waiman Long <longman@redhat.com>
>>>>> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>>>>> Signed-off-by: Ben Gardon <bgardon@google.com>
>>>> When building mips:defconfig, this patch results in:
>>>>
>>>> Error log:
>>>> In file included from include/linux/spinlock.h:90,
>>>>                    from include/linux/ipc.h:5,
>>>>                    from include/uapi/linux/sem.h:5,
>>>>                    from include/linux/sem.h:5,
>>>>                    from include/linux/compat.h:14,
>>>>                    from arch/mips/kernel/asm-offsets.c:12:
>>>> arch/mips/include/asm/spinlock.h:17:28: error: redefinition of 
>>>> 'queued_spin_unlock'
>>>>      17 | #define queued_spin_unlock queued_spin_unlock
>>>>         |                            ^~~~~~~~~~~~~~~~~~
>>>> arch/mips/include/asm/spinlock.h:22:20: note: in expansion of macro 
>>>> 'queued_spin_unlock'
>>>>      22 | static inline void queued_spin_unlock(struct qspinlock 
>>>> *lock)
>>>>         |                    ^~~~~~~~~~~~~~~~~~
>>>> In file included from include/asm-generic/qrwlock.h:17,
>>>>                    from ./arch/mips/include/generated/asm/qrwlock.h:1,
>>>>                    from arch/mips/include/asm/spinlock.h:13,
>>>>                    from include/linux/spinlock.h:90,
>>>>                    from include/linux/ipc.h:5,
>>>>                    from include/uapi/linux/sem.h:5,
>>>>                    from include/linux/sem.h:5,
>>>>                    from include/linux/compat.h:14,
>>>>                    from arch/mips/kernel/asm-offsets.c:12:
>>>> include/asm-generic/qspinlock.h:94:29: note: previous definition of 
>>>> 'queued_spin_unlock' was here
>>>>      94 | static __always_inline void queued_spin_unlock(struct 
>>>> qspinlock *lock)
>>>>         |                             ^~~~~~~~~~~~~~~~~~
>>> I think the compile error is caused by the improper header file 
>>> inclusion
>>> ordering. Can you try the following change to see if it can fix the 
>>> compile
>>> error?
>>>
>> That results in:
>>
>> In file included from ./arch/mips/include/generated/asm/qrwlock.h:1,
>>                   from ./arch/mips/include/asm/spinlock.h:13,
>>                   from ./include/linux/spinlock.h:90,
>>                   from ./include/linux/ipc.h:5,
>>                   from ./include/uapi/linux/sem.h:5,
>>                   from ./include/linux/sem.h:5,
>>                   from ./include/linux/compat.h:14,
>>                   from arch/mips/kernel/asm-offsets.c:12:
>> ./include/asm-generic/qrwlock.h: In function 
>> 'queued_rwlock_is_contended':
>> ./include/asm-generic/qrwlock.h:127:9: error: implicit declaration of 
>> function 'arch_spin_is_locked'
>>
>> Guenter
>
> It is because in arch/mips/include/asm/spinlock.h, asm/qrwlock.h is 
> included before asm/qspinlock.h. The compilation error should be gone 
> if the asm/qrwlock.h is removed or moved after asm/qspinlock.h. 

After thinking a bit more, I think we should remove asm/qrwlock.h in 
arch/mips/include/asm/spinlock.h. qrwlock and qspinlocks are 
independent. An architecture can include one but not the other. Also 
there is no point in including qrwlock.h in a asm/spinlock.h.

Regards,
Longman


  reply	other threads:[~2021-02-10  2:03 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02 18:57 [PATCH v2 00/28] Allow parallel MMU operations with TDP MMU Ben Gardon
2021-02-02 18:57 ` [PATCH v2 01/28] KVM: x86/mmu: change TDP MMU yield function returns to match cond_resched Ben Gardon
2021-02-02 18:57 ` [PATCH v2 02/28] KVM: x86/mmu: Add comment on __tdp_mmu_set_spte Ben Gardon
2021-02-02 18:57 ` [PATCH v2 03/28] KVM: x86/mmu: Add lockdep when setting a TDP MMU SPTE Ben Gardon
2021-02-02 18:57 ` [PATCH v2 04/28] KVM: x86/mmu: Don't redundantly clear TDP MMU pt memory Ben Gardon
2021-02-02 18:57 ` [PATCH v2 05/28] KVM: x86/mmu: Factor out handling of removed page tables Ben Gardon
2021-02-02 18:57 ` [PATCH v2 06/28] locking/rwlocks: Add contention detection for rwlocks Ben Gardon
2021-02-09 20:39   ` Guenter Roeck
2021-02-09 21:46     ` Waiman Long
2021-02-09 22:25       ` Guenter Roeck
2021-02-10  0:27         ` Waiman Long
2021-02-10  0:41           ` Waiman Long [this message]
2021-02-10  6:04           ` Guenter Roeck
2021-02-10 14:57             ` Waiman Long
2021-02-10  3:32   ` Waiman Long
2021-02-10 15:15     ` Waiman Long
2021-02-02 18:57 ` [PATCH v2 07/28] sched: Add needbreak " Ben Gardon
2021-02-02 18:57 ` [PATCH v2 08/28] sched: Add cond_resched_rwlock Ben Gardon
2021-02-02 18:57 ` [PATCH v2 09/28] KVM: x86/mmu: Fix braces in kvm_recover_nx_lpages Ben Gardon
2021-02-02 18:57 ` [PATCH v2 10/28] KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs Ben Gardon
2021-02-03  9:43   ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 11/28] KVM: x86/mmu: Merge flush and non-flush tdp_mmu_iter_cond_resched Ben Gardon
2021-02-02 18:57 ` [PATCH v2 12/28] KVM: x86/mmu: Rename goal_gfn to next_last_level_gfn Ben Gardon
2021-02-02 18:57 ` [PATCH v2 13/28] KVM: x86/mmu: Ensure forward progress when yielding in TDP MMU iter Ben Gardon
2021-02-05 23:42   ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 14/28] KVM: x86/mmu: Yield in TDU MMU iter even if no SPTES changed Ben Gardon
2021-02-02 18:57 ` [PATCH v2 15/28] KVM: x86/mmu: Skip no-op changes in TDP MMU functions Ben Gardon
2021-02-02 18:57 ` [PATCH v2 16/28] KVM: x86/mmu: Clear dirtied pages mask bit before early break Ben Gardon
2021-02-02 18:57 ` [PATCH v2 17/28] KVM: x86/mmu: Protect TDP MMU page table memory with RCU Ben Gardon
2021-02-02 18:57 ` [PATCH v2 18/28] KVM: x86/mmu: Use an rwlock for the x86 MMU Ben Gardon
2021-02-02 18:57 ` [PATCH v2 19/28] KVM: x86/mmu: Factor out functions to add/remove TDP MMU pages Ben Gardon
2021-02-02 18:57 ` [PATCH v2 20/28] KVM: x86/mmu: Use atomic ops to set SPTEs in TDP MMU map Ben Gardon
2021-02-03  2:48   ` kernel test robot
2021-02-03 11:14   ` Paolo Bonzini
2021-02-06  0:26     ` Sean Christopherson
2021-02-08 10:32       ` Paolo Bonzini
2021-04-01 10:32   ` Paolo Bonzini
2021-04-01 16:50     ` Ben Gardon
2021-04-01 17:32       ` Paolo Bonzini
2021-04-01 18:09         ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 21/28] KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler Ben Gardon
2021-02-06  0:29   ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 22/28] KVM: x86/mmu: Mark SPTEs in disconnected pages as removed Ben Gardon
2021-02-03 11:17   ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 23/28] KVM: x86/mmu: Allow parallel page faults for the TDP MMU Ben Gardon
2021-02-03 12:39   ` Paolo Bonzini
2021-02-03 17:46     ` Ben Gardon
2021-02-03 18:30       ` Paolo Bonzini
2021-02-06  0:12         ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 24/28] KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock Ben Gardon
2021-02-03 11:25   ` Paolo Bonzini
2021-02-03 11:26   ` Paolo Bonzini
2021-02-03 18:31     ` Ben Gardon
2021-02-03 18:32       ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 25/28] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU " Ben Gardon
2021-02-03 11:34   ` Paolo Bonzini
2021-02-03 18:51     ` Ben Gardon
2021-02-02 18:57 ` [PATCH v2 26/28] KVM: x86/mmu: Allow enabling / disabling dirty logging under " Ben Gardon
2021-02-03 11:38   ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 27/28] KVM: selftests: Add backing src parameter to dirty_log_perf_test Ben Gardon
2021-02-02 18:57 ` [PATCH v2 28/28] KVM: selftests: Disable dirty logging with vCPUs running Ben Gardon
2021-02-03 10:07   ` Paolo Bonzini
2021-02-03 11:00 ` [PATCH v2 00/28] Allow parallel MMU operations with TDP MMU Paolo Bonzini
2021-02-03 17:54   ` Sean Christopherson
2021-02-03 18:13     ` Paolo Bonzini

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