diff options
| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2014-11-25 13:17:34 +0100 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2014-12-18 09:54:41 +0100 |
| commit | 5de72a2247ac05bde7c89039631b3d0c6186fafb (patch) | |
| tree | 8ba7addcad7793f8e5ce0034c7f0a41a9039e222 | |
| parent | 488beef1440e845751365202faace2465840ea98 (diff) | |
s390/kvm: REPLACE barrier fixup with READ_ONCE
ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)
Commit 1365039d0cb3 ("KVM: s390: Fix ipte locking") replace
ACCESS_ONCE with barriers. Lets use READ_ONCE instead.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | arch/s390/kvm/gaccess.c | 18 |
1 files changed, 6 insertions, 12 deletions
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index 6dc0ad9c705..8f195fa904a 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -229,12 +229,10 @@ static void ipte_lock_simple(struct kvm_vcpu *vcpu) goto out; ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); while (old.k) { cond_resched(); - old = *ic; - barrier(); + old = READ_ONCE(*ic); } new = old; new.k = 1; @@ -253,8 +251,7 @@ static void ipte_unlock_simple(struct kvm_vcpu *vcpu) goto out; ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); new = old; new.k = 0; } while (cmpxchg(&ic->val, old.val, new.val) != old.val); @@ -269,12 +266,10 @@ static void ipte_lock_siif(struct kvm_vcpu *vcpu) ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); while (old.kg) { cond_resched(); - old = *ic; - barrier(); + old = READ_ONCE(*ic); } new = old; new.k = 1; @@ -288,8 +283,7 @@ static void ipte_unlock_siif(struct kvm_vcpu *vcpu) ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); new = old; new.kh--; if (!new.kh) |