rcu/sync: Kill rcu_sync_type/gp_type

Now that the RCU flavors have been consolidated, rcu_sync_type makes no
sense because none of internal update functions aside from .held() depend
on gp_type.  This commit therefore removes this field and consolidates
the relevant code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
[ paulmck: Added RCU and RCU-bh checks to rcu_sync_is_idle(). ]
[ paulmck: And applied subsequent feedback from Oleg Nesterov. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 03cb4b6f842eaa9bee0dea42a50854e42025c5f4..6887636ea1691bb4b57f1d91b1a67524aa653aca 100644 (file)
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -20,7 +20,7 @@ struct percpu_rw_semaphore {
 #define DEFINE_STATIC_PERCPU_RWSEM(name)                               \
 static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name);         \
 static struct percpu_rw_semaphore name = {                             \
-       .rss = __RCU_SYNC_INITIALIZER(name.rss, RCU_SCHED_SYNC),        \
+       .rss = __RCU_SYNC_INITIALIZER(name.rss),                        \
        .read_count = &__percpu_rwsem_rc_##name,                        \
        .rw_sem = __RWSEM_INITIALIZER(name.rw_sem),                     \
        .writer = __RCUWAIT_INITIALIZER(name.writer),                   \

diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
index 6fc53a1345b305117b566caf6a248e44cd113d6c..87971e85519c453d458ab7ef5c831d2f8075abbb 100644 (file)
--- a/include/linux/rcu_sync.h
+++ b/include/linux/rcu_sync.h
@@ -13,8 +13,6 @@
 #include <linux/wait.h>
 #include <linux/rcupdate.h>
 
-enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
-
 /* Structure to mediate between updaters and fastpath-using readers.  */
 struct rcu_sync {
        int                     gp_state;
@@ -23,52 +21,38 @@ struct rcu_sync {
 
        int                     cb_state;
        struct rcu_head         cb_head;
-
-       enum rcu_sync_type      gp_type;
 };
 
-extern void rcu_sync_lockdep_assert(struct rcu_sync *);
-
 /**
  * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
  * @rsp: Pointer to rcu_sync structure to use for synchronization
  *
- * Returns true if readers are permitted to use their fastpaths.
- * Must be invoked within an RCU read-side critical section whose
- * flavor matches that of the rcu_sync struture.
+ * Returns true if readers are permitted to use their fastpaths.  Must be
+ * invoked within some flavor of RCU read-side critical section.
  */
 static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
 {
-#ifdef CONFIG_PROVE_RCU
-       rcu_sync_lockdep_assert(rsp);
-#endif
+       RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
+                        !rcu_read_lock_bh_held() &&
+                        !rcu_read_lock_sched_held(),
+                        "suspicious rcu_sync_is_idle() usage");
        return !rsp->gp_state; /* GP_IDLE */
 }
 
-extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
+extern void rcu_sync_init(struct rcu_sync *);
 extern void rcu_sync_enter_start(struct rcu_sync *);
 extern void rcu_sync_enter(struct rcu_sync *);
 extern void rcu_sync_exit(struct rcu_sync *);
 extern void rcu_sync_dtor(struct rcu_sync *);
 
-#define __RCU_SYNC_INITIALIZER(name, type) {                           \
+#define __RCU_SYNC_INITIALIZER(name) {                                 \
                .gp_state = 0,                                          \
                .gp_count = 0,                                          \
                .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
                .cb_state = 0,                                          \
-               .gp_type = type,                                        \
        }
 
-#define        __DEFINE_RCU_SYNC(name, type)   \
-       struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)
-
-#define DEFINE_RCU_SYNC(name)          \
-       __DEFINE_RCU_SYNC(name, RCU_SYNC)
-
-#define DEFINE_RCU_SCHED_SYNC(name)    \
-       __DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)
-
-#define DEFINE_RCU_BH_SYNC(name)       \
-       __DEFINE_RCU_SYNC(name, RCU_BH_SYNC)
+#define        DEFINE_RCU_SYNC(name)   \
+       struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)
 
 #endif /* _LINUX_RCU_SYNC_H_ */

diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
index f17dad99eec8b76ca3e1b83963308ac6a4c10a7d..48cab93a47fdaba5eb0180cdc962ca331beeb62a 100644 (file)
--- a/kernel/locking/percpu-rwsem.c
+++ b/kernel/locking/percpu-rwsem.c
@@ -17,7 +17,7 @@ int __percpu_init_rwsem(struct percpu_rw_semaphore *sem,
                return -ENOMEM;
 
        /* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */
-       rcu_sync_init(&sem->rss, RCU_SCHED_SYNC);
+       rcu_sync_init(&sem->rss);
        __init_rwsem(&sem->rw_sem, name, rwsem_key);
        rcuwait_init(&sem->writer);
        sem->readers_block = 0;

diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c
index a8304d90573ff6bd93ac50865dbf094df6d33755..ee427e138dad3c18ed49ccfa2744faffb21663c5 100644 (file)
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -10,65 +10,20 @@
 #include <linux/rcu_sync.h>
 #include <linux/sched.h>
 
-#ifdef CONFIG_PROVE_RCU
-#define __INIT_HELD(func)      .held = func,
-#else
-#define __INIT_HELD(func)
-#endif
-
-static const struct {
-       void (*sync)(void);
-       void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
-       void (*wait)(void);
-#ifdef CONFIG_PROVE_RCU
-       int  (*held)(void);
-#endif
-} gp_ops[] = {
-       [RCU_SYNC] = {
-               .sync = synchronize_rcu,
-               .call = call_rcu,
-               .wait = rcu_barrier,
-               __INIT_HELD(rcu_read_lock_held)
-       },
-       [RCU_SCHED_SYNC] = {
-               .sync = synchronize_rcu,
-               .call = call_rcu,
-               .wait = rcu_barrier,
-               __INIT_HELD(rcu_read_lock_sched_held)
-       },
-       [RCU_BH_SYNC] = {
-               .sync = synchronize_rcu,
-               .call = call_rcu,
-               .wait = rcu_barrier,
-               __INIT_HELD(rcu_read_lock_bh_held)
-       },
-};
-
 enum { GP_IDLE = 0, GP_PENDING, GP_PASSED };
 enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY };
 
 #define        rss_lock        gp_wait.lock
 
-#ifdef CONFIG_PROVE_RCU
-void rcu_sync_lockdep_assert(struct rcu_sync *rsp)
-{
-       RCU_LOCKDEP_WARN(!gp_ops[rsp->gp_type].held(),
-                        "suspicious rcu_sync_is_idle() usage");
-}
-
-EXPORT_SYMBOL_GPL(rcu_sync_lockdep_assert);
-#endif
-
 /**
  * rcu_sync_init() - Initialize an rcu_sync structure
  * @rsp: Pointer to rcu_sync structure to be initialized
  * @type: Flavor of RCU with which to synchronize rcu_sync structure
  */
-void rcu_sync_init(struct rcu_sync *rsp, enum rcu_sync_type type)
+void rcu_sync_init(struct rcu_sync *rsp)
 {
        memset(rsp, 0, sizeof(*rsp));
        init_waitqueue_head(&rsp->gp_wait);
-       rsp->gp_type = type;
 }
 
 /**
@@ -114,7 +69,7 @@ void rcu_sync_enter(struct rcu_sync *rsp)
 
        WARN_ON_ONCE(need_wait && need_sync);
        if (need_sync) {
-               gp_ops[rsp->gp_type].sync();
+               synchronize_rcu();
                rsp->gp_state = GP_PASSED;
                wake_up_all(&rsp->gp_wait);
        } else if (need_wait) {
@@ -167,7 +122,7 @@ static void rcu_sync_func(struct rcu_head *rhp)
                 * to catch a later GP.
                 */
                rsp->cb_state = CB_PENDING;
-               gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func);
+               call_rcu(&rsp->cb_head, rcu_sync_func);
        } else {
                /*
                 * We're at least a GP after rcu_sync_exit(); eveybody will now
@@ -195,7 +150,7 @@ void rcu_sync_exit(struct rcu_sync *rsp)
        if (!--rsp->gp_count) {
                if (rsp->cb_state == CB_IDLE) {
                        rsp->cb_state = CB_PENDING;
-                       gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func);
+                       call_rcu(&rsp->cb_head, rcu_sync_func);
                } else if (rsp->cb_state == CB_PENDING) {
                        rsp->cb_state = CB_REPLAY;
                }
@@ -220,7 +175,7 @@ void rcu_sync_dtor(struct rcu_sync *rsp)
        spin_unlock_irq(&rsp->rss_lock);
 
        if (cb_state != CB_IDLE) {
-               gp_ops[rsp->gp_type].wait();
+               rcu_barrier();
                WARN_ON_ONCE(rsp->cb_state != CB_IDLE);
        }
 }