diff options
| -rw-r--r-- | include/linux/rcupdate.h | 126 | ||||
| -rw-r--r-- | include/linux/srcu.h | 87 | ||||
| -rw-r--r-- | kernel/rcupdate.c | 10 | ||||
| -rw-r--r-- | kernel/rcutorture.c | 12 | ||||
| -rw-r--r-- | kernel/srcu.c | 50 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 12 | ||||
| -rw-r--r-- | lib/debug_locks.c | 1 |
7 files changed, 267 insertions, 31 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 24440f4bf476..e3d37efe2703 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 4765d97dcafb..adbe1670b366 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 9b7fd4723878..033cb55c26df 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 adda92bfafac..5f43f30fcd1d 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 31b275b9c112..bde4295774c8 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 6bf97d176326..6af20a8a0a54 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 bc3b11731b9c..5bf0020b9248 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 |