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| author | Davidlohr Bueso <dave@stgolabs.net> | 2017-09-13 23:08:21 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-09-15 17:57:12 +0300 |
| commit | a0cff57bb2a41cb9cbf13d3203097b4156d8c0ae (patch) | |
| tree | db128f5fac2c228a01f314174b20db01b3412316 | |
| parent | cc1b46803a671047be22f7832ef4a2bb3f63dd94 (diff) | |
| download | linux-a0cff57bb2a41cb9cbf13d3203097b4156d8c0ae.tar.xz | |
kvm,x86: Fix apf_task_wake_one() wq serialization
During code inspection, the following potential race was seen:
CPU0 CPU1
kvm_async_pf_task_wait apf_task_wake_one
[L] swait_active(&n->wq)
[S] prepare_to_swait(&n.wq)
[L] if (!hlist_unhahed(&n.link))
schedule() [S] hlist_del_init(&n->link);
Properly serialize swait_active() checks such that a wakeup is
not missed.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kernel/kvm.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 874827b0d7ca..aa60a08b65b1 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -180,7 +180,7 @@ static void apf_task_wake_one(struct kvm_task_sleep_node *n) hlist_del_init(&n->link); if (n->halted) smp_send_reschedule(n->cpu); - else if (swait_active(&n->wq)) + else if (swq_has_sleeper(&n->wq)) swake_up(&n->wq); } |