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authorMark Rutland <mark.rutland@arm.com>2017-10-24 00:07:29 +0300
committerIngo Molnar <mingo@kernel.org>2017-10-25 12:01:08 +0300
commit6aa7de059173a986114ac43b8f50b297a86f09a8 (patch)
tree77666afe795e022914ca26433d61686c694dc4fd /arch/x86/kvm
parentb03a0fe0c5e4b46dcd400d27395b124499554a71 (diff)
downloadlinux-6aa7de059173a986114ac43b8f50b297a86f09a8.tar.xz
locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()
Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/mmu.c4
-rw-r--r--arch/x86/kvm/page_track.c2
2 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 7a69cf053711..a119b361b8b7 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -443,7 +443,7 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
static u64 __get_spte_lockless(u64 *sptep)
{
- return ACCESS_ONCE(*sptep);
+ return READ_ONCE(*sptep);
}
#else
union split_spte {
@@ -4819,7 +4819,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
* If we don't have indirect shadow pages, it means no page is
* write-protected, so we can exit simply.
*/
- if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages))
+ if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages))
return;
remote_flush = local_flush = false;
diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
index ea67dc876316..01c1371f39f8 100644
--- a/arch/x86/kvm/page_track.c
+++ b/arch/x86/kvm/page_track.c
@@ -157,7 +157,7 @@ bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
return false;
index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
- return !!ACCESS_ONCE(slot->arch.gfn_track[mode][index]);
+ return !!READ_ONCE(slot->arch.gfn_track[mode][index]);
}
void kvm_page_track_cleanup(struct kvm *kvm)