On Mon, 18 May 2020 at 18:36, Paolo Bonzini <[email protected]> wrote: > > On 24/04/20 07:48, Davidlohr Bueso wrote: > > +/* > > + * Note: this provides no serialization and, just as with waitqueues, > > + * requires care to estimate as to whether or not the wait is active. > > + */ > > +static inline int rcuwait_active(struct rcuwait *w) > > +{ > > + return !!rcu_dereference(w->task); > > +} > > This needs to be changed to rcu_access_pointer: > > > --------------- 8< ----------------- > From: Paolo Bonzini <[email protected]> > Subject: [PATCH] rcuwait: avoid lockdep splats from rcuwait_active() > > rcuwait_active only returns whether w->task is not NULL. This is > exactly one of the usecases that are mentioned in the documentation > for rcu_access_pointer() where it is correct to bypass lockdep checks. > > This avoids a splat from kvm_vcpu_on_spin(). > > Reported-by: Wanpeng Li <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Signed-off-by: Paolo Bonzini <[email protected]>
Tested-by: Wanpeng Li <[email protected]>
