lkml.org 
[lkml]   [2011]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v4] kvm: make vcpu life cycle separated from kvm instance
    On 12/15/2011 02:53 PM, Liu ping fan wrote:


    >
    >>> +struct kvm_vcpu *kvm_vcpu_get(struct kvm_vcpu *vcpu)
    >>> +{
    >>> + if (vcpu == NULL)
    >>> + return NULL;
    >>> + if (atomic_add_unless(&vcpu->refcount, 1, 0))
    >>
    >>
    >> Why do not use atomic_inc()?
    >> Also, i think a memory barrier is needed after increasing refcount.
    >>
    > Because when refcout==0, we prepare to destroy vcpu, and do not to
    > disturb it by increasing the refcount.


    Oh, get it.

    > And sorry but I can not figure out the scene why memory barrier needed
    > here. Seems no risks on SMP.
    >


    If atomic_add_unless is necessary, memory barrier is not needed here.



    \
     
     \ /
      Last update: 2011-12-15 09:29    [W:0.030 / U:64.296 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site