bitops: protect variables in set_mask_bits() macro

[linux-2.6-block.git] / kernel / tracepoint.c

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 6dc6356c3327c8a1d4958d686f84d5fb804f02d2..bf2c06ef9afc3d5c2a5eecb620aa9acb07a7bba5 100644 (file)
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -31,6 +31,9 @@
 extern struct tracepoint * const __start___tracepoints_ptrs[];
 extern struct tracepoint * const __stop___tracepoints_ptrs[];
 
+DEFINE_SRCU(tracepoint_srcu);
+EXPORT_SYMBOL_GPL(tracepoint_srcu);
+
 /* Set to 1 to enable tracepoint debug output */
 static const int tracepoint_debug;
 
@@ -50,6 +53,9 @@ static LIST_HEAD(tracepoint_module_list);
  */
 static DEFINE_MUTEX(tracepoints_mutex);
 
+static struct rcu_head *early_probes;
+static bool ok_to_free_tracepoints;
+
 /*
  * Note about RCU :
  * It is used to delay the free of multiple probes array until a quiescent
@@ -67,16 +73,56 @@ static inline void *allocate_probes(int count)
        return p == NULL ? NULL : p->probes;
 }
 
-static void rcu_free_old_probes(struct rcu_head *head)
+static void srcu_free_old_probes(struct rcu_head *head)
 {
        kfree(container_of(head, struct tp_probes, rcu));
 }
 
+static void rcu_free_old_probes(struct rcu_head *head)
+{
+       call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
+}
+
+static __init int release_early_probes(void)
+{
+       struct rcu_head *tmp;
+
+       ok_to_free_tracepoints = true;
+
+       while (early_probes) {
+               tmp = early_probes;
+               early_probes = tmp->next;
+               call_rcu_sched(tmp, rcu_free_old_probes);
+       }
+
+       return 0;
+}
+
+/* SRCU is initialized at core_initcall */
+postcore_initcall(release_early_probes);
+
 static inline void release_probes(struct tracepoint_func *old)
 {
        if (old) {
                struct tp_probes *tp_probes = container_of(old,
                        struct tp_probes, probes[0]);
+
+               /*
+                * We can't free probes if SRCU is not initialized yet.
+                * Postpone the freeing till after SRCU is initialized.
+                */
+               if (unlikely(!ok_to_free_tracepoints)) {
+                       tp_probes->rcu.next = early_probes;
+                       early_probes = &tp_probes->rcu;
+                       return;
+               }
+
+               /*
+                * Tracepoint probes are protected by both sched RCU and SRCU,
+                * by calling the SRCU callback in the sched RCU callback we
+                * cover both cases. So let us chain the SRCU and sched RCU
+                * callbacks to wait for both grace periods.
+                */
                call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
        }
 }
@@ -325,6 +371,27 @@ int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
 }
 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
 
+static void for_each_tracepoint_range(struct tracepoint * const *begin,
+               struct tracepoint * const *end,
+               void (*fct)(struct tracepoint *tp, void *priv),
+               void *priv)
+{
+       if (!begin)
+               return;
+
+       if (IS_ENABLED(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)) {
+               const int *iter;
+
+               for (iter = (const int *)begin; iter < (const int *)end; iter++)
+                       fct(offset_to_ptr(iter), priv);
+       } else {
+               struct tracepoint * const *iter;
+
+               for (iter = begin; iter < end; iter++)
+                       fct(*iter, priv);
+       }
+}
+
 #ifdef CONFIG_MODULES
 bool trace_module_has_bad_taint(struct module *mod)
 {
@@ -389,15 +456,9 @@ EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
  * Ensure the tracer unregistered the module's probes before the module
  * teardown is performed. Prevents leaks of probe and data pointers.
  */
-static void tp_module_going_check_quiescent(struct tracepoint * const *begin,
-               struct tracepoint * const *end)
+static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)
 {
-       struct tracepoint * const *iter;
-
-       if (!begin)
-               return;
-       for (iter = begin; iter < end; iter++)
-               WARN_ON_ONCE((*iter)->funcs);
+       WARN_ON_ONCE(tp->funcs);
 }
 
 static int tracepoint_module_coming(struct module *mod)
@@ -448,8 +509,9 @@ static void tracepoint_module_going(struct module *mod)
                         * Called the going notifier before checking for
                         * quiescence.
                         */
-                       tp_module_going_check_quiescent(mod->tracepoints_ptrs,
-                               mod->tracepoints_ptrs + mod->num_tracepoints);
+                       for_each_tracepoint_range(mod->tracepoints_ptrs,
+                               mod->tracepoints_ptrs + mod->num_tracepoints,
+                               tp_module_going_check_quiescent, NULL);
                        break;
                }
        }
@@ -501,19 +563,6 @@ static __init int init_tracepoints(void)
 __initcall(init_tracepoints);
 #endif /* CONFIG_MODULES */
 
-static void for_each_tracepoint_range(struct tracepoint * const *begin,
-               struct tracepoint * const *end,
-               void (*fct)(struct tracepoint *tp, void *priv),
-               void *priv)
-{
-       struct tracepoint * const *iter;
-
-       if (!begin)
-               return;
-       for (iter = begin; iter < end; iter++)
-               fct(*iter, priv);
-}
-
 /**
  * for_each_kernel_tracepoint - iteration on all kernel tracepoints
  * @fct: callback