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[RFC PATCH 04/10] preempt: use atomic_t to for preempt_count
- To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Date: Tue, 23 Feb 2021 02:34:56 +0000
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- Cc: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Ian Jackson <iwj@xxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Tue, 23 Feb 2021 02:35:15 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Thread-index: AQHXCYx5c7ga2XxajUiE7SdBv/dfFA==
- Thread-topic: [RFC PATCH 04/10] preempt: use atomic_t to for preempt_count
This ensures that preempt_count will be accounted correctly
during in-hypevisor context switches.
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
---
xen/common/preempt.c | 6 +++---
xen/include/xen/preempt.h | 9 ++++-----
2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/xen/common/preempt.c b/xen/common/preempt.c
index 3b4178fd44..ad61c8419a 100644
--- a/xen/common/preempt.c
+++ b/xen/common/preempt.c
@@ -23,17 +23,17 @@
#include <xen/irq.h>
#include <asm/system.h>
-DEFINE_PER_CPU(unsigned int, __preempt_count);
+DEFINE_PER_CPU(atomic_t, __preempt_count);
bool_t in_atomic(void)
{
- return preempt_count() || in_irq() || !local_irq_is_enabled();
+ return atomic_read(&preempt_count()) || in_irq() || local_irq_is_enabled();
}
#ifndef NDEBUG
void ASSERT_NOT_IN_ATOMIC(void)
{
- ASSERT(!preempt_count());
+ ASSERT(!atomic_read(&preempt_count()));
ASSERT(!in_irq());
ASSERT(local_irq_is_enabled());
}
diff --git a/xen/include/xen/preempt.h b/xen/include/xen/preempt.h
index bef83135a1..e217900d6e 100644
--- a/xen/include/xen/preempt.h
+++ b/xen/include/xen/preempt.h
@@ -9,21 +9,20 @@
#ifndef __XEN_PREEMPT_H__
#define __XEN_PREEMPT_H__
+#include <asm/atomic.h>
#include <xen/types.h>
#include <xen/percpu.h>
-DECLARE_PER_CPU(unsigned int, __preempt_count);
+DECLARE_PER_CPU(atomic_t, __preempt_count);
#define preempt_count() (this_cpu(__preempt_count))
#define preempt_disable() do { \
- preempt_count()++; \
- barrier(); \
+ atomic_inc(&preempt_count()); \
} while (0)
#define preempt_enable() do { \
- barrier(); \
- preempt_count()--; \
+ atomic_dec(&preempt_count()); \
} while (0)
bool_t in_atomic(void);
--
2.29.2
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