Implement statedump request notifications
[libside.git] / src / side.c
index 54e0b6a9481420ada73c1d51028889d5effeea25..045ffcf643825a9439e1807a1c391b7adbc9be32 100644 (file)
@@ -5,6 +5,7 @@
 
 #include <side/trace.h>
 #include <string.h>
+#include <assert.h>
 
 #include "rcu.h"
 #include "list.h"
@@ -37,6 +38,25 @@ struct side_tracer_handle {
        void *priv;
 };
 
+struct side_statedump_request_handle {
+       struct side_list_node node;
+       void (*cb)(void);
+};
+
+struct side_callback {
+       union {
+               void (*call)(const struct side_event_description *desc,
+                       const struct side_arg_vec *side_arg_vec,
+                       void *priv);
+               void (*call_variadic)(const struct side_event_description *desc,
+                       const struct side_arg_vec *side_arg_vec,
+                       const struct side_arg_dynamic_struct *var_struct,
+                       void *priv);
+       } u;
+       void *priv;
+       void *key;
+};
+
 static struct side_rcu_gp_state rcu_gp;
 
 /*
@@ -55,16 +75,24 @@ static pthread_mutex_t side_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
 
 static DEFINE_SIDE_LIST_HEAD(side_events_list);
 static DEFINE_SIDE_LIST_HEAD(side_tracer_list);
+static DEFINE_SIDE_LIST_HEAD(side_statedump_list);
+
+/*
+ * Callback filter key for state dump.
+ */
+static __thread void *filter_key;
 
 /*
  * The empty callback has a NULL function callback pointer, which stops
  * iteration on the array of callbacks immediately.
  */
-const struct side_callback side_empty_callback = { };
+const char side_empty_callback[sizeof(struct side_callback)];
 
-void side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec)
+static
+void _side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec, void *key)
 {
        struct side_rcu_read_state rcu_read_state;
+       const struct side_event_state_0 *es0;
        const struct side_callback *side_cb;
        uintptr_t enabled;
 
@@ -72,25 +100,42 @@ void side_call(const struct side_event_state *event_state, const struct side_arg
                return;
        if (side_unlikely(!initialized))
                side_init();
-       if (side_unlikely(event_state->desc->flags & SIDE_EVENT_FLAG_VARIADIC)) {
-               printf("ERROR: unexpected variadic event description\n");
+       if (side_unlikely(event_state->version != 0))
                abort();
-       }
-       enabled = __atomic_load_n(&event_state->enabled, __ATOMIC_RELAXED);
+       es0 = side_container_of(event_state, const struct side_event_state_0, parent);
+       assert(!(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC));
+       enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
        if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
                // TODO: call kernel write.
        }
        side_rcu_read_begin(&rcu_gp, &rcu_read_state);
-       for (side_cb = side_rcu_dereference(event_state->callbacks); side_cb->u.call != NULL; side_cb++)
-               side_cb->u.call(event_state->desc, side_arg_vec, side_cb->priv);
+       for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++) {
+               /* A NULL key is always a match. */
+               if (key && side_cb->key && side_cb->key != key)
+                       continue;
+               side_cb->u.call(es0->desc, side_arg_vec, side_cb->priv);
+       }
        side_rcu_read_end(&rcu_gp, &rcu_read_state);
 }
 
-void side_call_variadic(const struct side_event_state *event_state,
+void side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec)
+{
+       _side_call(event_state, side_arg_vec, NULL);
+}
+
+void side_statedump_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec)
+{
+       _side_call(event_state, side_arg_vec, filter_key);
+}
+
+static
+void _side_call_variadic(const struct side_event_state *event_state,
        const struct side_arg_vec *side_arg_vec,
-       const struct side_arg_dynamic_struct *var_struct)
+       const struct side_arg_dynamic_struct *var_struct,
+       void *key)
 {
        struct side_rcu_read_state rcu_read_state;
+       const struct side_event_state_0 *es0;
        const struct side_callback *side_cb;
        uintptr_t enabled;
 
@@ -98,30 +143,52 @@ void side_call_variadic(const struct side_event_state *event_state,
                return;
        if (side_unlikely(!initialized))
                side_init();
-       if (side_unlikely(!(event_state->desc->flags & SIDE_EVENT_FLAG_VARIADIC))) {
-               printf("ERROR: unexpected non-variadic event description\n");
+       if (side_unlikely(event_state->version != 0))
                abort();
-       }
-       enabled = __atomic_load_n(&event_state->enabled, __ATOMIC_RELAXED);
+       es0 = side_container_of(event_state, const struct side_event_state_0, parent);
+       assert(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC);
+       enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
        if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
                // TODO: call kernel write.
        }
        side_rcu_read_begin(&rcu_gp, &rcu_read_state);
-       for (side_cb = side_rcu_dereference(event_state->callbacks); side_cb->u.call_variadic != NULL; side_cb++)
-               side_cb->u.call_variadic(event_state->desc, side_arg_vec, var_struct, side_cb->priv);
+       for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++) {
+               /* A NULL key is always a match. */
+               if (key && side_cb->key && side_cb->key != key)
+                       continue;
+               side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv);
+       }
        side_rcu_read_end(&rcu_gp, &rcu_read_state);
 }
 
+void side_call_variadic(const struct side_event_state *event_state,
+       const struct side_arg_vec *side_arg_vec,
+       const struct side_arg_dynamic_struct *var_struct)
+{
+       _side_call_variadic(event_state, side_arg_vec, var_struct, NULL);
+}
+
+void side_statedump_call_variadic(const struct side_event_state *event_state,
+       const struct side_arg_vec *side_arg_vec,
+       const struct side_arg_dynamic_struct *var_struct)
+{
+       _side_call_variadic(event_state, side_arg_vec, var_struct, filter_key);
+}
+
 static
 const struct side_callback *side_tracer_callback_lookup(
                const struct side_event_description *desc,
-               void *call, void *priv)
+               void *call, void *priv, void *key)
 {
        struct side_event_state *event_state = side_ptr_get(desc->state);
+       const struct side_event_state_0 *es0;
        const struct side_callback *cb;
 
-       for (cb = event_state->callbacks; cb->u.call != NULL; cb++) {
-               if ((void *) cb->u.call == call && cb->priv == priv)
+       if (side_unlikely(event_state->version != 0))
+               abort();
+       es0 = side_container_of(event_state, const struct side_event_state_0, parent);
+       for (cb = es0->callbacks; cb->u.call != NULL; cb++) {
+               if ((void *) cb->u.call == call && cb->priv == priv && cb->key == key)
                        return cb;
        }
        return NULL;
@@ -129,10 +196,11 @@ const struct side_callback *side_tracer_callback_lookup(
 
 static
 int _side_tracer_callback_register(struct side_event_description *desc,
-               void *call, void *priv)
+               void *call, void *priv, void *key)
 {
        struct side_event_state *event_state;
        struct side_callback *old_cb, *new_cb;
+       struct side_event_state_0 *es0;
        int ret = SIDE_ERROR_OK;
        uint32_t old_nr_cb;
 
@@ -144,17 +212,20 @@ int _side_tracer_callback_register(struct side_event_description *desc,
                side_init();
        pthread_mutex_lock(&side_lock);
        event_state = side_ptr_get(desc->state);
-       old_nr_cb = desc->nr_callbacks;
+       if (side_unlikely(event_state->version != 0))
+               abort();
+       es0 = side_container_of(event_state, struct side_event_state_0, parent);
+       old_nr_cb = es0->nr_callbacks;
        if (old_nr_cb == UINT32_MAX) {
                ret = SIDE_ERROR_INVAL;
                goto unlock;
        }
        /* Reject duplicate (call, priv) tuples. */
-       if (side_tracer_callback_lookup(desc, call, priv)) {
+       if (side_tracer_callback_lookup(desc, call, priv, key)) {
                ret = SIDE_ERROR_EXIST;
                goto unlock;
        }
-       old_cb = (struct side_callback *) event_state->callbacks;
+       old_cb = (struct side_callback *) es0->callbacks;
        /* old_nr_cb + 1 (new cb) + 1 (NULL) */
        new_cb = (struct side_callback *) calloc(old_nr_cb + 2, sizeof(struct side_callback));
        if (!new_cb) {
@@ -169,14 +240,16 @@ int _side_tracer_callback_register(struct side_event_description *desc,
                new_cb[old_nr_cb].u.call =
                        (side_tracer_callback_func) call;
        new_cb[old_nr_cb].priv = priv;
-       side_rcu_assign_pointer(event_state->callbacks, new_cb);
+       new_cb[old_nr_cb].key = key;
+       /* High order bits are already zeroed. */
+       side_rcu_assign_pointer(es0->callbacks, new_cb);
        side_rcu_wait_grace_period(&rcu_gp);
        if (old_nr_cb)
                free(old_cb);
-       desc->nr_callbacks++;
+       es0->nr_callbacks++;
        /* Increment concurrently with kernel setting the top bits. */
        if (!old_nr_cb)
-               (void) __atomic_add_fetch(&event_state->enabled, 1, __ATOMIC_RELAXED);
+               (void) __atomic_add_fetch(&es0->enabled, 1, __ATOMIC_RELAXED);
 unlock:
        pthread_mutex_unlock(&side_lock);
        return ret;
@@ -184,28 +257,29 @@ unlock:
 
 int side_tracer_callback_register(struct side_event_description *desc,
                side_tracer_callback_func call,
-               void *priv)
+               void *priv, void *key)
 {
        if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
                return SIDE_ERROR_INVAL;
-       return _side_tracer_callback_register(desc, (void *) call, priv);
+       return _side_tracer_callback_register(desc, (void *) call, priv, key);
 }
 
 int side_tracer_callback_variadic_register(struct side_event_description *desc,
                side_tracer_callback_variadic_func call_variadic,
-               void *priv)
+               void *priv, void *key)
 {
        if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
                return SIDE_ERROR_INVAL;
-       return _side_tracer_callback_register(desc, (void *) call_variadic, priv);
+       return _side_tracer_callback_register(desc, (void *) call_variadic, priv, key);
 }
 
 static int _side_tracer_callback_unregister(struct side_event_description *desc,
-               void *call, void *priv)
+               void *call, void *priv, void *key)
 {
        struct side_event_state *event_state;
        struct side_callback *old_cb, *new_cb;
        const struct side_callback *cb_pos;
+       struct side_event_state_0 *es0;
        uint32_t pos_idx;
        int ret = SIDE_ERROR_OK;
        uint32_t old_nr_cb;
@@ -218,17 +292,20 @@ static int _side_tracer_callback_unregister(struct side_event_description *desc,
                side_init();
        pthread_mutex_lock(&side_lock);
        event_state = side_ptr_get(desc->state);
-       cb_pos = side_tracer_callback_lookup(desc, call, priv);
+       if (side_unlikely(event_state->version != 0))
+               abort();
+       es0 = side_container_of(event_state, struct side_event_state_0, parent);
+       cb_pos = side_tracer_callback_lookup(desc, call, priv, key);
        if (!cb_pos) {
                ret = SIDE_ERROR_NOENT;
                goto unlock;
        }
-       old_nr_cb = desc->nr_callbacks;
-       old_cb = (struct side_callback *) event_state->callbacks;
+       old_nr_cb = es0->nr_callbacks;
+       old_cb = (struct side_callback *) es0->callbacks;
        if (old_nr_cb == 1) {
                new_cb = (struct side_callback *) &side_empty_callback;
        } else {
-               pos_idx = cb_pos - event_state->callbacks;
+               pos_idx = cb_pos - es0->callbacks;
                /* Remove entry at pos_idx. */
                /* old_nr_cb - 1 (removed cb) + 1 (NULL) */
                new_cb = (struct side_callback *) calloc(old_nr_cb, sizeof(struct side_callback));
@@ -239,13 +316,14 @@ static int _side_tracer_callback_unregister(struct side_event_description *desc,
                memcpy(new_cb, old_cb, pos_idx);
                memcpy(&new_cb[pos_idx], &old_cb[pos_idx + 1], old_nr_cb - pos_idx - 1);
        }
-       side_rcu_assign_pointer(event_state->callbacks, new_cb);
+       /* High order bits are already zeroed. */
+       side_rcu_assign_pointer(es0->callbacks, new_cb);
        side_rcu_wait_grace_period(&rcu_gp);
        free(old_cb);
-       desc->nr_callbacks--;
+       es0->nr_callbacks--;
        /* Decrement concurrently with kernel setting the top bits. */
        if (old_nr_cb == 1)
-               (void) __atomic_add_fetch(&event_state->enabled, -1, __ATOMIC_RELAXED);
+               (void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
 unlock:
        pthread_mutex_unlock(&side_lock);
        return ret;
@@ -253,20 +331,20 @@ unlock:
 
 int side_tracer_callback_unregister(struct side_event_description *desc,
                side_tracer_callback_func call,
-               void *priv)
+               void *priv, void *key)
 {
        if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
                return SIDE_ERROR_INVAL;
-       return _side_tracer_callback_unregister(desc, (void *) call, priv);
+       return _side_tracer_callback_unregister(desc, (void *) call, priv, key);
 }
 
 int side_tracer_callback_variadic_unregister(struct side_event_description *desc,
                side_tracer_callback_variadic_func call_variadic,
-               void *priv)
+               void *priv, void *key)
 {
        if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
                return SIDE_ERROR_INVAL;
-       return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv);
+       return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv, key);
 }
 
 struct side_events_register_handle *side_events_register(struct side_event_description **events, uint32_t nr_events)
@@ -300,20 +378,25 @@ static
 void side_event_remove_callbacks(struct side_event_description *desc)
 {
        struct side_event_state *event_state = side_ptr_get(desc->state);
-       uint32_t nr_cb = desc->nr_callbacks;
+       struct side_event_state_0 *es0;
        struct side_callback *old_cb;
+       uint32_t nr_cb;
 
+       if (side_unlikely(event_state->version != 0))
+               abort();
+       es0 = side_container_of(event_state, struct side_event_state_0, parent);
+       nr_cb = es0->nr_callbacks;
        if (!nr_cb)
                return;
-       old_cb = (struct side_callback *) event_state->callbacks;
-       (void) __atomic_add_fetch(&event_state->enabled, -1, __ATOMIC_RELAXED);
+       old_cb = (struct side_callback *) es0->callbacks;
+       (void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
        /*
         * Setting the state back to 0 cb and empty callbacks out of
         * caution. This should not matter because instrumentation is
         * unreachable.
         */
-       desc->nr_callbacks = 0;
-       side_rcu_assign_pointer(event_state->callbacks, &side_empty_callback);
+       es0->nr_callbacks = 0;
+       side_rcu_assign_pointer(es0->callbacks, &side_empty_callback);
        /*
         * No need to wait for grace period because instrumentation is
         * unreachable.
@@ -403,6 +486,58 @@ void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer
        free(tracer_handle);
 }
 
+struct side_statedump_request_handle *side_statedump_request_notification_register(void (*statedump_cb)(void))
+{
+       struct side_statedump_request_handle *handle;
+
+       if (finalized)
+               return NULL;
+       if (!initialized)
+               side_init();
+       /*
+        * The statedump request notification should not be registered
+        * from a notification callback.
+        */
+       assert(filter_key == NULL);
+       handle = (struct side_statedump_request_handle *)
+                               calloc(1, sizeof(struct side_statedump_request_handle));
+       if (!handle)
+               return NULL;
+       pthread_mutex_lock(&side_lock);
+       handle->cb = statedump_cb;
+       side_list_insert_node_tail(&side_statedump_list, &handle->node);
+       /* Invoke callback for all tracers. */
+       statedump_cb();
+       pthread_mutex_unlock(&side_lock);
+       return handle;
+}
+
+void side_statedump_request_notification_unregister(struct side_statedump_request_handle *handle)
+{
+       if (finalized)
+               return;
+       if (!initialized)
+               side_init();
+       assert(filter_key == NULL);
+       pthread_mutex_lock(&side_lock);
+       side_list_remove_node(&handle->node);
+       pthread_mutex_unlock(&side_lock);
+       free(handle);
+}
+
+void side_tracer_statedump_request(void *key)
+{
+       struct side_statedump_request_handle *handle;
+
+       /* Invoke the state dump callback specifically for the tracer key. */
+       filter_key = key;
+       pthread_mutex_lock(&side_lock);
+       side_list_for_each_entry(handle, &side_statedump_list, node)
+               handle->cb();
+       pthread_mutex_unlock(&side_lock);
+       filter_key = NULL;
+}
+
 void side_init(void)
 {
        if (initialized)
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