On Mon, 18 May 2020, Paolo Bonzini 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 <pbonzini@xxxxxxxxxx> 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 <kernellwp@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Acked-by: Davidlohr Bueso <dbueso@xxxxxxx>
