> > + spin_lock_irqsave(&per_cpu(pi_blocked_vcpu_lock, pi_block_cpu), > flags); > > + > > + /* > > + * v->arch.hvm_vmx.pi_block_cpu == NR_CPUS here means the vCPU > was > > + * removed from the blocking list while we are acquiring the lock. > > + */ > > + if ( v->arch.hvm_vmx.pi_block_cpu == NR_CPUS ) > > With you wanting to deal with changes behind your back here, > isn't there come kind of barrier needed between reading and using > pi_block_cpu, such that the compiler won't convert the local > variable accesses into multiple reads of > v->arch.hvm_vmx.pi_block_cpu (which iiuc it is allowed to do)? >
Thinking about this more. Seems we call spin_lock_irqsave() before using ' v->arch.hvm_vmx.pi_block_cpu ', can spin_lock_irqsave() used as the serializing instruction here? IIRIC, spin lock operations can be used for this purpose, right? Thanks, Feng _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
