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