path: root/virt
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authorDavid Woodhouse <>2020-10-27 14:39:43 +0000
committerPaolo Bonzini <>2020-11-15 09:49:09 -0500
commitc4d51a52c67a1e3a0fa3006e5ec21cdc07649cd6 (patch)
tree8197d1c61f4fe778e4cc86e1c7715bdcd9116d17 /virt
parentbf0cd88ce363a2de3684baaa48d3f194acdc516c (diff)
sched/wait: Add add_wait_queue_priority()
This allows an exclusive wait_queue_entry to be added at the head of the queue, instead of the tail as normal. Thus, it gets to consume events first without allowing non-exclusive waiters to be woken at all. The (first) intended use is for KVM IRQFD, which currently has inconsistent behaviour depending on whether posted interrupts are available or not. If they are, KVM will bypass the eventfd completely and deliver interrupts directly to the appropriate vCPU. If not, events are delivered through the eventfd and userspace will receive them when polling on the eventfd. By using add_wait_queue_priority(), KVM will be able to consistently consume events within the kernel without accidentally exposing them to userspace when they're supposed to be bypassed. This, in turn, means that userspace doesn't have to jump through hoops to avoid listening on the erroneously noisy eventfd and injecting duplicate interrupts. Signed-off-by: David Woodhouse <> Message-Id: <> Signed-off-by: Paolo Bonzini <>
Diffstat (limited to 'virt')
0 files changed, 0 insertions, 0 deletions