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| author |   Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-20 16:48:59 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-20 16:48:59 -0800 |
| commit | 60815cf2e05057db5b78e398d9734c493560b11e (patch) | |
| tree | 23d7f55df13cc5a0c072cc8a6f361f8e7050b825 /arch/s390/kvm/gaccess.c | |
| parent | Merge tag 'clk-for-linus-3.19' of git://git.linaro.org/people/mike.turquette/linux (diff) | |
| parent | s390/kvm: REPLACE barrier fixup with READ_ONCE (diff) | |
| download | linux-dev-60815cf2e05057db5b78e398d9734c493560b11e.tar.xz linux-dev-60815cf2e05057db5b78e398d9734c493560b11e.zip | |
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux
Pull ACCESS_ONCE cleanup preparation from Christian Borntraeger:
"kernel: Provide READ_ONCE and ASSIGN_ONCE
As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com
ACCESS_ONCE might fail with specific compilers for non-scalar
accesses.
Here is a set of patches to tackle that problem.
The first patch introduce READ_ONCE and ASSIGN_ONCE. If the data
structure is larger than the machine word size memcpy is used and a
warning is emitted. The next patches fix up several in-tree users of
ACCESS_ONCE on non-scalar types.
This does not yet contain a patch that forces ACCESS_ONCE to work only
on scalar types. This is targetted for the next merge window as Linux
next already contains new offenders regarding ACCESS_ONCE vs.
non-scalar types"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux:
s390/kvm: REPLACE barrier fixup with READ_ONCE
arm/spinlock: Replace ACCESS_ONCE with READ_ONCE
arm64/spinlock: Replace ACCESS_ONCE READ_ONCE
mips/gup: Replace ACCESS_ONCE with READ_ONCE
x86/gup: Replace ACCESS_ONCE with READ_ONCE
x86/spinlock: Replace ACCESS_ONCE with READ_ONCE
mm: replace ACCESS_ONCE with READ_ONCE or barriers
kernel: Provide READ_ONCE and ASSIGN_ONCE
Diffstat (limited to 'arch/s390/kvm/gaccess.c')
| -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 8b9ccf02a2c5..8a1be9017730 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -227,12 +227,10 @@ 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; @@ -251,8 +249,7 @@ 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); @@ -267,12 +264,10 @@ 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; @@ -286,8 +281,7 @@ 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) |