Add a lock specific counter to rcu read locks in debug builds. This
allows to test for matching lock/unlock calls.
This will help to avoid cases like the one fixed by commit
98ed1f43cc2c89 where different rcu read locks were referenced in the
lock and unlock calls.
Signed-off-by: Juergen Gross
---
V5:
- updated commit message (Jan Beulich)
---
xen/include/xen/rcupdate.h | 46 +-
1 file changed, 33 insertions(+), 13 deletions(-)
diff --git a/xen/include/xen/rcupdate.h b/xen/include/xen/rcupdate.h
index d3c2b7b093..e0c3b16e7d 100644
--- a/xen/include/xen/rcupdate.h
+++ b/xen/include/xen/rcupdate.h
@@ -37,21 +37,50 @@
#include
#include
#include
+#include
#define __rcu
+#ifndef NDEBUG
+/* * Lock type for passing to rcu_read_{lock,unlock}. */
+struct _rcu_read_lock {
+atomic_t cnt;
+};
+typedef struct _rcu_read_lock rcu_read_lock_t;
+#define DEFINE_RCU_READ_LOCK(x) rcu_read_lock_t x = { .cnt = ATOMIC_INIT(0) }
+#define RCU_READ_LOCK_INIT(x) atomic_set(&(x)->cnt, 0)
+
+#else
+/*
+ * Dummy lock type for passing to rcu_read_{lock,unlock}. Currently exists
+ * only to document the reason for rcu_read_lock() critical sections.
+ */
+struct _rcu_read_lock {};
+typedef struct _rcu_read_lock rcu_read_lock_t;
+#define DEFINE_RCU_READ_LOCK(x) rcu_read_lock_t x
+#define RCU_READ_LOCK_INIT(x)
+
+#endif
+
DECLARE_PER_CPU(unsigned int, rcu_lock_cnt);
-static inline void rcu_quiesce_disable(void)
+static inline void rcu_quiesce_disable(rcu_read_lock_t *lock)
{
preempt_disable();
this_cpu(rcu_lock_cnt)++;
+#ifndef NDEBUG
+atomic_inc(>cnt);
+#endif
barrier();
}
-static inline void rcu_quiesce_enable(void)
+static inline void rcu_quiesce_enable(rcu_read_lock_t *lock)
{
barrier();
+#ifndef NDEBUG
+ASSERT(atomic_read(>cnt));
+atomic_dec(>cnt);
+#endif
this_cpu(rcu_lock_cnt)--;
preempt_enable();
}
@@ -81,15 +110,6 @@ struct rcu_head {
int rcu_pending(int cpu);
int rcu_needs_cpu(int cpu);
-/*
- * Dummy lock type for passing to rcu_read_{lock,unlock}. Currently exists
- * only to document the reason for rcu_read_lock() critical sections.
- */
-struct _rcu_read_lock {};
-typedef struct _rcu_read_lock rcu_read_lock_t;
-#define DEFINE_RCU_READ_LOCK(x) rcu_read_lock_t x
-#define RCU_READ_LOCK_INIT(x)
-
/**
* rcu_read_lock - mark the beginning of an RCU read-side critical section.
*
@@ -118,7 +138,7 @@ typedef struct _rcu_read_lock rcu_read_lock_t;
*/
static inline void rcu_read_lock(rcu_read_lock_t *lock)
{
-rcu_quiesce_disable();
+rcu_quiesce_disable(lock);
}
/**
@@ -129,7 +149,7 @@ static inline void rcu_read_lock(rcu_read_lock_t *lock)
static inline void rcu_read_unlock(rcu_read_lock_t *lock)
{
ASSERT(!rcu_quiesce_allowed());
-rcu_quiesce_enable();
+rcu_quiesce_enable(lock);
}
/*
--
2.16.4
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