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-rw-r--r--include/linux/rcupdate.h126
-rw-r--r--include/linux/srcu.h87
-rw-r--r--kernel/rcupdate.c10
-rw-r--r--kernel/rcutorture.c12
-rw-r--r--kernel/srcu.c50
-rw-r--r--lib/Kconfig.debug12
-rw-r--r--lib/debug_locks.c1
7 files changed, 267 insertions, 31 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 24440f4bf47..e3d37efe270 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -78,14 +78,120 @@ extern void rcu_init(void);
} while (0)
#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
extern struct lockdep_map rcu_lock_map;
-# define rcu_read_acquire() \
- lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_acquire() \
+ lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
# define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
-#else
-# define rcu_read_acquire() do { } while (0)
-# define rcu_read_release() do { } while (0)
-#endif
+
+extern struct lockdep_map rcu_bh_lock_map;
+# define rcu_read_acquire_bh() \
+ lock_acquire(&rcu_bh_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_release_bh() lock_release(&rcu_bh_lock_map, 1, _THIS_IP_)
+
+extern struct lockdep_map rcu_sched_lock_map;
+# define rcu_read_acquire_sched() \
+ lock_acquire(&rcu_sched_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_release_sched() \
+ lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
+
+/**
+ * rcu_read_lock_held - might we be in RCU read-side critical section?
+ *
+ * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
+ * an RCU read-side critical section. In absence of CONFIG_PROVE_LOCKING,
+ * this assumes we are in an RCU read-side critical section unless it can
+ * prove otherwise.
+ */
+static inline int rcu_read_lock_held(void)
+{
+ if (debug_locks)
+ return lock_is_held(&rcu_lock_map);
+ return 1;
+}
+
+/**
+ * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
+ *
+ * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
+ * an RCU-bh read-side critical section. In absence of CONFIG_PROVE_LOCKING,
+ * this assumes we are in an RCU-bh read-side critical section unless it can
+ * prove otherwise.
+ */
+static inline int rcu_read_lock_bh_held(void)
+{
+ if (debug_locks)
+ return lock_is_held(&rcu_bh_lock_map);
+ return 1;
+}
+
+/**
+ * rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
+ *
+ * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in an
+ * RCU-sched read-side critical section. In absence of CONFIG_PROVE_LOCKING,
+ * this assumes we are in an RCU-sched read-side critical section unless it
+ * can prove otherwise. Note that disabling of preemption (including
+ * disabling irqs) counts as an RCU-sched read-side critical section.
+ */
+static inline int rcu_read_lock_sched_held(void)
+{
+ int lockdep_opinion = 0;
+
+ if (debug_locks)
+ lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
+ return lockdep_opinion || preempt_count() != 0;
+}
+
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+# define rcu_read_acquire() do { } while (0)
+# define rcu_read_release() do { } while (0)
+# define rcu_read_acquire_bh() do { } while (0)
+# define rcu_read_release_bh() do { } while (0)
+# define rcu_read_acquire_sched() do { } while (0)
+# define rcu_read_release_sched() do { } while (0)
+
+static inline int rcu_read_lock_held(void)
+{
+ return 1;
+}
+
+static inline int rcu_read_lock_bh_held(void)
+{
+ return 1;
+}
+
+static inline int rcu_read_lock_sched_held(void)
+{
+ return preempt_count() != 0;
+}
+
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+#ifdef CONFIG_PROVE_RCU
+
+/**
+ * rcu_dereference_check - rcu_dereference with debug checking
+ *
+ * Do an rcu_dereference(), but check that the context is correct.
+ * For example, rcu_dereference_check(gp, rcu_read_lock_held()) to
+ * ensure that the rcu_dereference_check() executes within an RCU
+ * read-side critical section. It is also possible to check for
+ * locks being held, for example, by using lockdep_is_held().
+ */
+#define rcu_dereference_check(p, c) \
+ ({ \
+ if (debug_locks) \
+ WARN_ON_ONCE(!(c)); \
+ rcu_dereference(p); \
+ })
+
+#else /* #ifdef CONFIG_PROVE_RCU */
+
+#define rcu_dereference_check(p, c) rcu_dereference(p)
+
+#endif /* #else #ifdef CONFIG_PROVE_RCU */
/**
* rcu_read_lock - mark the beginning of an RCU read-side critical section.
@@ -160,7 +266,7 @@ static inline void rcu_read_lock_bh(void)
{
__rcu_read_lock_bh();
__acquire(RCU_BH);
- rcu_read_acquire();
+ rcu_read_acquire_bh();
}
/*
@@ -170,7 +276,7 @@ static inline void rcu_read_lock_bh(void)
*/
static inline void rcu_read_unlock_bh(void)
{
- rcu_read_release();
+ rcu_read_release_bh();
__release(RCU_BH);
__rcu_read_unlock_bh();
}
@@ -188,7 +294,7 @@ static inline void rcu_read_lock_sched(void)
{
preempt_disable();
__acquire(RCU_SCHED);
- rcu_read_acquire();
+ rcu_read_acquire_sched();
}
/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */
@@ -205,7 +311,7 @@ static inline notrace void rcu_read_lock_sched_notrace(void)
*/
static inline void rcu_read_unlock_sched(void)
{
- rcu_read_release();
+ rcu_read_release_sched();
__release(RCU_SCHED);
preempt_enable();
}
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 4765d97dcaf..adbe1670b36 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -35,6 +35,9 @@ struct srcu_struct {
int completed;
struct srcu_struct_array *per_cpu_ref;
struct mutex mutex;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ struct lockdep_map dep_map;
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
};
#ifndef CONFIG_PREEMPT
@@ -43,12 +46,92 @@ struct srcu_struct {
#define srcu_barrier()
#endif /* #else #ifndef CONFIG_PREEMPT */
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+int __init_srcu_struct(struct srcu_struct *sp, const char *name,
+ struct lock_class_key *key);
+
+#define init_srcu_struct(sp) \
+({ \
+ static struct lock_class_key __srcu_key; \
+ \
+ __init_srcu_struct((sp), #sp, &__srcu_key); \
+})
+
+# define srcu_read_acquire(sp) \
+ lock_acquire(&(sp)->dep_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define srcu_read_release(sp) \
+ lock_release(&(sp)->dep_map, 1, _THIS_IP_)
+
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
int init_srcu_struct(struct srcu_struct *sp);
+
+# define srcu_read_acquire(sp) do { } while (0)
+# define srcu_read_release(sp) do { } while (0)
+
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
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
+
+/**
+ * srcu_read_lock_held - might we be in SRCU read-side critical section?
+ *
+ * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
+ * an SRCU read-side critical section. In absence of CONFIG_PROVE_LOCKING,
+ * this assumes we are in an SRCU read-side critical section unless it can
+ * prove otherwise.
+ */
+static inline int srcu_read_lock_held(struct srcu_struct *sp)
+{
+ if (debug_locks)
+ return lock_is_held(&sp->dep_map);
+ return 1;
+}
+
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+static inline int srcu_read_lock_held(struct srcu_struct *sp)
+{
+ return 1;
+}
+
+#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(sp);
+ 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(sp);
+ __srcu_read_unlock(sp, idx);
+}
+
#endif
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 9b7fd472387..033cb55c26d 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -50,6 +50,16 @@ static struct lock_class_key rcu_lock_key;
struct lockdep_map rcu_lock_map =
STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
EXPORT_SYMBOL_GPL(rcu_lock_map);
+
+static struct lock_class_key rcu_bh_lock_key;
+struct lockdep_map rcu_bh_lock_map =
+ STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
+EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
+
+static struct lock_class_key rcu_sched_lock_key;
+struct lockdep_map rcu_sched_lock_map =
+ STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
+EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
#endif
/*
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index adda92bfafa..5f43f30fcd1 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -796,7 +796,11 @@ static void rcu_torture_timer(unsigned long unused)
idx = cur_ops->readlock();
completed = cur_ops->completed();
- p = rcu_dereference(rcu_torture_current);
+ p = rcu_dereference_check(rcu_torture_current,
+ rcu_read_lock_held() ||
+ rcu_read_lock_bh_held() ||
+ rcu_read_lock_sched_held() ||
+ srcu_read_lock_held(&srcu_ctl));
if (p == NULL) {
/* Leave because rcu_torture_writer is not yet underway */
cur_ops->readunlock(idx);
@@ -853,7 +857,11 @@ rcu_torture_reader(void *arg)
}
idx = cur_ops->readlock();
completed = cur_ops->completed();
- p = rcu_dereference(rcu_torture_current);
+ p = rcu_dereference_check(rcu_torture_current,
+ rcu_read_lock_held() ||
+ rcu_read_lock_bh_held() ||
+ rcu_read_lock_sched_held() ||
+ srcu_read_lock_held(&srcu_ctl));
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
cur_ops->readunlock(idx);
diff --git a/kernel/srcu.c b/kernel/srcu.c
index 31b275b9c11..bde4295774c 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -34,6 +34,30 @@
#include <linux/smp.h>
#include <linux/srcu.h>
+static int init_srcu_struct_fields(struct srcu_struct *sp)
+{
+ sp->completed = 0;
+ mutex_init(&sp->mutex);
+ sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
+ return sp->per_cpu_ref ? 0 : -ENOMEM;
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+int __init_srcu_struct(struct srcu_struct *sp, const char *name,
+ struct lock_class_key *key)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ /* Don't re-initialize a lock while it is held. */
+ debug_check_no_locks_freed((void *)sp, sizeof(*sp));
+ lockdep_init_map(&sp->dep_map, name, key, 0);
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+ return init_srcu_struct_fields(sp);
+}
+EXPORT_SYMBOL_GPL(__init_srcu_struct);
+
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
/**
* init_srcu_struct - initialize a sleep-RCU structure
* @sp: structure to initialize.
@@ -44,13 +68,12 @@
*/
int init_srcu_struct(struct srcu_struct *sp)
{
- sp->completed = 0;
- mutex_init(&sp->mutex);
- sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
- return (sp->per_cpu_ref ? 0 : -ENOMEM);
+ return init_srcu_struct_fields(sp);
}
EXPORT_SYMBOL_GPL(init_srcu_struct);
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
/*
* srcu_readers_active_idx -- returns approximate number of readers
* active on the specified rank of per-CPU counters.
@@ -100,15 +123,12 @@ 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 +140,22 @@ 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().
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 6bf97d17632..6af20a8a0a5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -499,6 +499,18 @@ config PROVE_LOCKING
For more details, see Documentation/lockdep-design.txt.
+config PROVE_RCU
+ bool "RCU debugging: prove RCU correctness"
+ depends on PROVE_LOCKING
+ default n
+ help
+ This feature enables lockdep extensions that check for correct
+ use of RCU APIs. This is currently under development. Say Y
+ if you want to debug RCU usage or help work on the PROVE_RCU
+ feature.
+
+ Say N if you are unsure.
+
config LOCKDEP
bool
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
diff --git a/lib/debug_locks.c b/lib/debug_locks.c
index bc3b11731b9..5bf0020b924 100644
--- a/lib/debug_locks.c
+++ b/lib/debug_locks.c
@@ -23,6 +23,7 @@
* shut up after that.
*/
int debug_locks = 1;
+EXPORT_SYMBOL_GPL(debug_locks);
/*
* The locking-testsuite uses <debug_locks_silent> to get a