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 <[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]>
Acked-by: Davidlohr Bueso <[email protected]>
