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Message-Id: <1260918161657-git-send-email->
Date: Tue, 15 Dec 2009 15:02:39 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
josh@...htriplett.org, dvhltc@...ibm.com, niv@...ibm.com,
tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
Valdis.Kletnieks@...edu, dhowells@...hat.com,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH RFC tip/core/rcu 16/18] rcu: make lockdep aware of SRCU read-side critical sections.
From: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Proposed for 2.6.34, not for inclusion.
This patch adds lockdep classes and code to make lockdep aware of
SRCU read-side critical sections.
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
include/linux/srcu.h | 44 ++++++++++++++++++++++++++++++++++++++++++--
kernel/srcu.c | 26 +++++++++++++-------------
2 files changed, 55 insertions(+), 15 deletions(-)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 4765d97..5a07b90 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -45,10 +45,50 @@ struct srcu_struct {
int init_srcu_struct(struct srcu_struct *sp);
void cleanup_srcu_struct(struct srcu_struct *sp);
-int srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
-void srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
+int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
+void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
void synchronize_srcu(struct srcu_struct *sp);
void synchronize_srcu_expedited(struct srcu_struct *sp);
long srcu_batches_completed(struct srcu_struct *sp);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern struct lockdep_map srcu_lock_map;
+# define srcu_read_acquire() \
+ lock_acquire(&srcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define srcu_read_release() \
+ lock_release(&srcu_lock_map, 1, _THIS_IP_)
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+# define srcu_read_acquire() do { } while (0)
+# define srcu_read_release() do { } while (0)
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+/**
+ * srcu_read_lock - register a new reader for an SRCU-protected structure.
+ * @sp: srcu_struct in which to register the new reader.
+ *
+ * Enter an SRCU read-side critical section. Note that SRCU read-side
+ * critical sections may be nested.
+ */
+static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
+{
+ int retval = __srcu_read_lock(sp);
+
+ srcu_read_acquire();
+ return retval;
+}
+
+/**
+ * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
+ * @sp: srcu_struct in which to unregister the old reader.
+ * @idx: return value from corresponding srcu_read_lock().
+ *
+ * Exit an SRCU read-side critical section.
+ */
+static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
+ __releases(sp)
+{
+ srcu_read_release();
+ __srcu_read_unlock(sp, idx);
+}
+
#endif
diff --git a/kernel/srcu.c b/kernel/srcu.c
index 818d7d9..4575f63 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -34,6 +34,13 @@
#include <linux/smp.h>
#include <linux/srcu.h>
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key srcu_lock_key;
+struct lockdep_map srcu_lock_map =
+ STATIC_LOCKDEP_MAP_INIT("srcu_read_lock", &srcu_lock_key);
+EXPORT_SYMBOL_GPL(srcu_lock_map);
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
/**
* init_srcu_struct - initialize a sleep-RCU structure
* @sp: structure to initialize.
@@ -100,15 +107,12 @@ void cleanup_srcu_struct(struct srcu_struct *sp)
}
EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
-/**
- * srcu_read_lock - register a new reader for an SRCU-protected structure.
- * @sp: srcu_struct in which to register the new reader.
- *
+/*
* Counts the new reader in the appropriate per-CPU element of the
* srcu_struct. Must be called from process context.
* Returns an index that must be passed to the matching srcu_read_unlock().
*/
-int srcu_read_lock(struct srcu_struct *sp)
+int __srcu_read_lock(struct srcu_struct *sp)
{
int idx;
@@ -120,26 +124,22 @@ int srcu_read_lock(struct srcu_struct *sp)
preempt_enable();
return idx;
}
-EXPORT_SYMBOL_GPL(srcu_read_lock);
+EXPORT_SYMBOL_GPL(__srcu_read_lock);
-/**
- * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
- * @sp: srcu_struct in which to unregister the old reader.
- * @idx: return value from corresponding srcu_read_lock().
- *
+/*
* Removes the count for the old reader from the appropriate per-CPU
* element of the srcu_struct. Note that this may well be a different
* CPU than that which was incremented by the corresponding srcu_read_lock().
* Must be called from process context.
*/
-void srcu_read_unlock(struct srcu_struct *sp, int idx)
+void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{
preempt_disable();
srcu_barrier(); /* ensure compiler won't misorder critical section. */
per_cpu_ptr(sp->per_cpu_ref, smp_processor_id())->c[idx]--;
preempt_enable();
}
-EXPORT_SYMBOL_GPL(srcu_read_unlock);
+EXPORT_SYMBOL_GPL(__srcu_read_unlock);
/*
* Helper function for synchronize_srcu() and synchronize_srcu_expedited().
--
1.5.2.5
--
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