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Groups > linux.kernel > #1731826

[PATCH v2 0/7] swait: Introduce and use swq_has_sleeper()

From Davidlohr Bueso <dave@stgolabs.net>
Newsgroups linux.kernel
Subject [PATCH v2 0/7] swait: Introduce and use swq_has_sleeper()
Date 2017-09-13 22:10 +0200
Message-ID <upm8V-3w4-9@gated-at.bofh.it> (permalink)
Organization linux.* mail to news gateway

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Changes from v1: https://lkml.org/lkml/2017/9/5/622
 - Added patch 7 (mips)
 - Small comment fixlets in patch 1.

Hi,

Recently[1] Nick mentioned that a lot of swait_active() callers look fishy.
This is because it inherited bad habits from regular waitqueues. Other than rcu,
kvm is one of the main callers, which I audited.

The following patches fix and/or justify (in baby steps) some of the
callers. The main exception is s390, which I didn't follow how ->valid_wakeup
can get hoisted as kvm_vcpu_block does not use that in the wait loop.

Thanks!

Davidlohr Bueso (7):
  sched/wait: Add swq_has_sleepers()
  kvm,async_pf: Use swq_has_sleepers()
  kvm,lapic: Justify use of swait_activate()
  kvm,x86: Fix apf_task_wake_one() wq serialization
  kvm: Serialize wq active checks in kvm_vcpu_wake_up()
  kvm,powerpc: Serialize wq active checks in ops->vcpu_kick
  kvm,mips: Fix potential swait_active() races

 arch/mips/kvm/mips.c         |  4 +--
 arch/powerpc/kvm/book3s_hv.c |  2 +-
 arch/x86/kernel/kvm.c        |  2 +-
 arch/x86/kvm/lapic.c         |  4 +++
 include/linux/swait.h        | 58 ++++++++++++++++++++++++++++++++++++++++++--
 virt/kvm/async_pf.c          |  6 +----
 virt/kvm/kvm_main.c          |  2 +-
 7 files changed, 66 insertions(+), 12 deletions(-)

-- 
2.12.0

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[PATCH v2 0/7] swait: Introduce and use swq_has_sleeper() Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:10 +0200
  [PATCH 7/7] kvm,mips: Fix potential swait_active() races Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:10 +0200
    Re: [PATCH 7/7] kvm,mips: Fix potential swait_active() races Paolo Bonzini <pbonzini@redhat.com> - 2017-09-13 22:40 +0200
      Re: [PATCH 7/7] kvm,mips: Fix potential swait_active() races Davidlohr Bueso <dave@stgolabs.net> - 2017-09-14 00:30 +0200
        Re: [PATCH 7/7] kvm,mips: Fix potential swait_active() races Paolo Bonzini <pbonzini@redhat.com> - 2017-09-15 13:40 +0200
  [PATCH 6/7] kvm,powerpc: Serialize wq active checks in ops->vcpu_kick Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:10 +0200
  [PATCH 4/7] kvm,x86: Fix apf_task_wake_one() wq serialization Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:20 +0200
  [PATCH 3/7] kvm,lapic: Justify use of swait_activate() Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:20 +0200
    Re: [PATCH 3/7] kvm,lapic: Justify use of swait_activate() Paolo Bonzini <pbonzini@redhat.com> - 2017-09-15 13:50 +0200
  [PATCH 2/7] kvm,async_pf: Use swq_has_sleepers() Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:20 +0200
  Re: [PATCH v2 0/7] swait: Introduce and use swq_has_sleeper() Paolo Bonzini <pbonzini@redhat.com> - 2017-09-15 14:00 +0200
    Re: [PATCH v2 0/7] swait: Introduce and use swq_has_sleeper() Christian Borntraeger <borntraeger@de.ibm.com> - 2017-09-19 10:30 +0200

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