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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
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')
-rw-r--r--arch/x86/entry/common.c2
-rw-r--r--arch/x86/entry/vdso/vclock_gettime.c2
-rw-r--r--arch/x86/events/core.c2
-rw-r--r--arch/x86/include/asm/vgtod.h2
-rw-r--r--arch/x86/kernel/espfix_64.c6
-rw-r--r--arch/x86/kernel/nmi.c2
-rw-r--r--arch/x86/kvm/mmu.c4
-rw-r--r--arch/x86/kvm/page_track.c2
-rw-r--r--arch/x86/xen/p2m.c2
9 files changed, 12 insertions, 12 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 03505ffbe1b6..eaa0ba66cf96 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -75,7 +75,7 @@ static long syscall_trace_enter(struct pt_regs *regs)
if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
BUG_ON(regs != task_pt_regs(current));
- work = ACCESS_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY;
+ work = READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY;
if (unlikely(work & _TIF_SYSCALL_EMU))
emulated = true;
diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index fa8dbfcf7ed3..11b13c4b43d5 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -318,7 +318,7 @@ int gettimeofday(struct timeval *, struct timezone *)
notrace time_t __vdso_time(time_t *t)
{
/* This is atomic on x86 so we don't need any locks. */
- time_t result = ACCESS_ONCE(gtod->wall_time_sec);
+ time_t result = READ_ONCE(gtod->wall_time_sec);
if (t)
*t = result;
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 589af1eec7c1..140d33288e78 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2118,7 +2118,7 @@ static int x86_pmu_event_init(struct perf_event *event)
event->destroy(event);
}
- if (ACCESS_ONCE(x86_pmu.attr_rdpmc))
+ if (READ_ONCE(x86_pmu.attr_rdpmc))
event->hw.flags |= PERF_X86_EVENT_RDPMC_ALLOWED;
return err;
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index 022e59714562..53dd162576a8 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -48,7 +48,7 @@ static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
unsigned ret;
repeat:
- ret = ACCESS_ONCE(s->seq);
+ ret = READ_ONCE(s->seq);
if (unlikely(ret & 1)) {
cpu_relax();
goto repeat;
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index 9c4e7ba6870c..7d7715dde901 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -155,14 +155,14 @@ void init_espfix_ap(int cpu)
page = cpu/ESPFIX_STACKS_PER_PAGE;
/* Did another CPU already set this up? */
- stack_page = ACCESS_ONCE(espfix_pages[page]);
+ stack_page = READ_ONCE(espfix_pages[page]);
if (likely(stack_page))
goto done;
mutex_lock(&espfix_init_mutex);
/* Did we race on the lock? */
- stack_page = ACCESS_ONCE(espfix_pages[page]);
+ stack_page = READ_ONCE(espfix_pages[page]);
if (stack_page)
goto unlock_done;
@@ -200,7 +200,7 @@ void init_espfix_ap(int cpu)
set_pte(&pte_p[n*PTE_STRIDE], pte);
/* Job is done for this CPU and any CPU which shares this page */
- ACCESS_ONCE(espfix_pages[page]) = stack_page;
+ WRITE_ONCE(espfix_pages[page], stack_page);
unlock_done:
mutex_unlock(&espfix_init_mutex);
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 35aafc95e4b8..18bc9b51ac9b 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -105,7 +105,7 @@ static void nmi_max_handler(struct irq_work *w)
{
struct nmiaction *a = container_of(w, struct nmiaction, irq_work);
int remainder_ns, decimal_msecs;
- u64 whole_msecs = ACCESS_ONCE(a->max_duration);
+ u64 whole_msecs = READ_ONCE(a->max_duration);
remainder_ns = do_div(whole_msecs, (1000 * 1000));
decimal_msecs = remainder_ns / 1000;
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)
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 6083ba462f35..13b4f19b9131 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -547,7 +547,7 @@ int xen_alloc_p2m_entry(unsigned long pfn)
if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
topidx = p2m_top_index(pfn);
top_mfn_p = &p2m_top_mfn[topidx];
- mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
+ mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]);
BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);