On 11/13/14 3:41, Christoffer Dall wrote: > On Wed, Nov 12, 2014 at 11:04:23PM +0800, Chen Gang wrote: >> When mutex_trylock() fails, kvm_vgic_create() will not create 'vgic', so >> it need return failure code '-EBUSY' instead of '0' to let outside know >> about it. > > I already sent a patch for the -EBUSY: > https://lists.cs.columbia.edu/pipermail/kvmarm/2014-November/011936.html > Yeah, really it is. >> >> Also simplify the code within kvm_vgic_create(): >> >> - kvm_for_each_vcpu() scanning once is enough for current case. >> >> - Remove redundant variable 'vcpu_lock_idx'. > > I don't like using the iterator variable for this kind of thing because > it can really break in languages where i is out-of-scope after the loop > and it is too easy to reuse the iterator variable in later versions of > the code. > For me, what you said is OK, we can still keep it no touch. > That being said, the scanning once is slightly prettier I guess, > but I'd rather not introduce the churn unless others (Marc) think this > is a big win. > If only merge the 2 scanning loops, it will not change much. And also can let code simpler and clearer for readers (both are for processing and checking '-EBUSY'). If possible, after your patch merges into linux next tree, I will send the related improving patch for it. Thanks. > -Christoffer > >> >> >> Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx> >> --- >> virt/kvm/arm/vgic.c | 15 +++++++-------- >> 1 file changed, 7 insertions(+), 8 deletions(-) >> >> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c >> index 3aaca49..5846725 100644 >> --- a/virt/kvm/arm/vgic.c >> +++ b/virt/kvm/arm/vgic.c >> @@ -1933,7 +1933,7 @@ out: >> >> int kvm_vgic_create(struct kvm *kvm) >> { >> - int i, vcpu_lock_idx = -1, ret = 0; >> + int i, ret = 0; >> struct kvm_vcpu *vcpu; >> >> mutex_lock(&kvm->lock); >> @@ -1949,13 +1949,12 @@ int kvm_vgic_create(struct kvm *kvm) >> * that no other VCPUs are run while we create the vgic. >> */ >> kvm_for_each_vcpu(i, vcpu, kvm) { >> - if (!mutex_trylock(&vcpu->mutex)) >> + if (!mutex_trylock(&vcpu->mutex)) { >> + ret = -EBUSY; >> goto out_unlock; >> - vcpu_lock_idx = i; >> - } >> - >> - kvm_for_each_vcpu(i, vcpu, kvm) { >> + } >> if (vcpu->arch.has_run_once) { >> + mutex_unlock(&vcpu->mutex); >> ret = -EBUSY; >> goto out_unlock; >> } >> @@ -1968,8 +1967,8 @@ int kvm_vgic_create(struct kvm *kvm) >> kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF; >> >> out_unlock: >> - for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) { >> - vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx); >> + while (i-- > 0) { >> + vcpu = kvm_get_vcpu(kvm, i); >> mutex_unlock(&vcpu->mutex); >> } >> >> -- >> 1.9.3 -- Chen Gang Open, share, and attitude like air, water, and life which God blessed -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
