diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/percpu-rwsem.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/lib/percpu-rwsem.c b/lib/percpu-rwsem.c index ce92ab563a08..652a8ee8efe9 100644 --- a/lib/percpu-rwsem.c +++ b/lib/percpu-rwsem.c @@ -2,18 +2,21 @@ #include <linux/rwsem.h> #include <linux/percpu.h> #include <linux/wait.h> +#include <linux/lockdep.h> #include <linux/percpu-rwsem.h> #include <linux/rcupdate.h> #include <linux/sched.h> #include <linux/errno.h> -int percpu_init_rwsem(struct percpu_rw_semaphore *brw) +int __percpu_init_rwsem(struct percpu_rw_semaphore *brw, + const char *name, struct lock_class_key *rwsem_key) { brw->fast_read_ctr = alloc_percpu(int); if (unlikely(!brw->fast_read_ctr)) return -ENOMEM; - init_rwsem(&brw->rw_sem); + /* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */ + __init_rwsem(&brw->rw_sem, name, rwsem_key); atomic_set(&brw->write_ctr, 0); atomic_set(&brw->slow_read_ctr, 0); init_waitqueue_head(&brw->write_waitq); @@ -66,19 +69,29 @@ static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val) /* * Like the normal down_read() this is not recursive, the writer can * come after the first percpu_down_read() and create the deadlock. + * + * Note: returns with lock_is_held(brw->rw_sem) == T for lockdep, + * percpu_up_read() does rwsem_release(). This pairs with the usage + * of ->rw_sem in percpu_down/up_write(). */ void percpu_down_read(struct percpu_rw_semaphore *brw) { - if (likely(update_fast_ctr(brw, +1))) + might_sleep(); + if (likely(update_fast_ctr(brw, +1))) { + rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_); return; + } down_read(&brw->rw_sem); atomic_inc(&brw->slow_read_ctr); - up_read(&brw->rw_sem); + /* avoid up_read()->rwsem_release() */ + __up_read(&brw->rw_sem); } void percpu_up_read(struct percpu_rw_semaphore *brw) { + rwsem_release(&brw->rw_sem.dep_map, 1, _RET_IP_); + if (likely(update_fast_ctr(brw, -1))) return; |