*/
#include <side/trace.h>
-#include "tracer.h"
+#include <string.h>
+#include <assert.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <poll.h>
-#define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x80000000
+#include "compiler.h"
+#include "rcu.h"
+#include "list.h"
+#include "rculist.h"
-void side_call(const struct side_event_description *desc, const struct side_arg_vec_description *sav_desc)
+/* Top 8 bits reserved for shared tracer use. */
+#if SIDE_BITS_PER_LONG == 64
+# define SIDE_EVENT_ENABLED_SHARED_MASK 0xFF00000000000000ULL
+# define SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK 0x8000000000000000ULL
+# define SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK 0x4000000000000000ULL
+
+/* Allow 2^56 private tracer references on an event. */
+# define SIDE_EVENT_ENABLED_PRIVATE_MASK 0x00FFFFFFFFFFFFFFULL
+#else
+# define SIDE_EVENT_ENABLED_SHARED_MASK 0xFF000000UL
+# define SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK 0x80000000UL
+# define SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK 0x40000000UL
+
+/* Allow 2^24 private tracer references on an event. */
+# define SIDE_EVENT_ENABLED_PRIVATE_MASK 0x00FFFFFFUL
+#endif
+
+#define SIDE_KEY_RESERVED_RANGE_END 0x8
+
+/* Key 0x0 is reserved to match all. */
+#define SIDE_KEY_MATCH_ALL 0x0
+/* Key 0x1 is reserved for user event. */
+#define SIDE_KEY_USER_EVENT 0x1
+/* Key 0x2 is reserved for ptrace. */
+#define SIDE_KEY_PTRACE 0x2
+
+#define SIDE_RETRY_BUSY_LOOP_ATTEMPTS 100
+#define SIDE_RETRY_DELAY_MS 1
+
+struct side_events_register_handle {
+ struct side_list_node node;
+ struct side_event_description **events;
+ uint32_t nr_events;
+};
+
+struct side_tracer_handle {
+ struct side_list_node node;
+ void (*cb)(enum side_tracer_notification notif,
+ struct side_event_description **events, uint32_t nr_events, void *priv);
+ void *priv;
+};
+
+struct side_statedump_notification {
+ struct side_list_node node;
+ uint64_t key;
+};
+
+struct side_statedump_request_handle {
+ struct side_list_node node; /* Statedump request RCU list node. */
+ struct side_list_head notification_queue; /* Queue of struct side_statedump_notification */
+ void (*cb)(void);
+ char *name;
+ enum side_statedump_mode mode;
+};
+
+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;
+ uint64_t key;
+};
+
+enum agent_thread_state {
+ AGENT_THREAD_STATE_BLOCKED = 0,
+ AGENT_THREAD_STATE_HANDLE_REQUEST = (1 << 0),
+ AGENT_THREAD_STATE_EXIT = (1 << 1),
+ AGENT_THREAD_STATE_PAUSE = (1 << 2),
+ AGENT_THREAD_STATE_PAUSE_ACK = (1 << 3),
+};
+
+struct statedump_agent_thread {
+ long ref;
+ pthread_t id;
+ enum agent_thread_state state;
+ pthread_cond_t worker_cond;
+ pthread_cond_t waiter_cond;
+};
+
+static struct side_rcu_gp_state event_rcu_gp, statedump_rcu_gp;
+
+/*
+ * Lazy initialization for early use within library constructors.
+ */
+static bool initialized;
+/*
+ * Do not register/unregister any more events after destructor.
+ */
+static bool finalized;
+
+/*
+ * Recursive mutex to allow tracer callbacks to use the side API.
+ */
+static pthread_mutex_t side_event_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+static pthread_mutex_t side_statedump_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+static pthread_mutex_t side_key_lock = PTHREAD_MUTEX_INITIALIZER;
+/*
+ * The side_agent_thread_lock protects the life-time of the agent
+ * thread: reference counting, creation, join. It is not taken by
+ * the agent thread per se so it does not have a circular dependency
+ * with pthread join.
+ * The side_statedump_lock nests inside the side_agent_thread_lock.
+ */
+static pthread_mutex_t side_agent_thread_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/* Dynamic tracer key allocation. */
+static uint64_t side_key_next = SIDE_KEY_RESERVED_RANGE_END;
+
+static struct statedump_agent_thread statedump_agent_thread;
+
+static DEFINE_SIDE_LIST_HEAD(side_events_list);
+static DEFINE_SIDE_LIST_HEAD(side_tracer_list);
+
+/*
+ * The statedump request list is a RCU list to allow the agent thread to
+ * iterate over this list with a RCU read-side lock.
+ */
+static DEFINE_SIDE_LIST_HEAD(side_statedump_list);
+
+/*
+ * Callback filter key for state dump.
+ */
+static __thread uint64_t filter_key = SIDE_KEY_MATCH_ALL;
+
+/*
+ * The empty callback has a NULL function callback pointer, which stops
+ * iteration on the array of callbacks immediately.
+ */
+const char side_empty_callback[sizeof(struct side_callback)];
+
+side_static_event(side_statedump_begin, "side", "statedump_begin",
+ SIDE_LOGLEVEL_INFO, side_field_list(side_field_string("name")));
+side_static_event(side_statedump_end, "side", "statedump_end",
+ SIDE_LOGLEVEL_INFO, side_field_list(side_field_string("name")));
+
+/*
+ * side_ptrace_hook is a place holder for a debugger breakpoint.
+ * var_struct is NULL if not variadic.
+ */
+void side_ptrace_hook(const struct side_event_state *event_state __attribute__((unused)),
+ const struct side_arg_vec *side_arg_vec __attribute__((unused)),
+ const struct side_arg_dynamic_struct *var_struct __attribute__((unused)))
+ __attribute__((noinline));
+void side_ptrace_hook(const struct side_event_state *event_state __attribute__((unused)),
+ const struct side_arg_vec *side_arg_vec __attribute__((unused)),
+ const struct side_arg_dynamic_struct *var_struct __attribute__((unused)))
+{
+}
+
+static
+void _side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec, uint64_t 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;
+
+ if (side_unlikely(finalized))
+ return;
+ if (side_unlikely(!initialized))
+ side_init();
+ if (side_unlikely(event_state->version != 0))
+ abort();
+ 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_SHARED_MASK)) {
+ if ((enabled & SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK) &&
+ (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_USER_EVENT)) {
+ // TODO: call kernel write.
+ }
+ if ((enabled & SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK) &&
+ (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_PTRACE))
+ side_ptrace_hook(event_state, side_arg_vec, NULL);
+ }
+ side_rcu_read_begin(&event_rcu_gp, &rcu_read_state);
+ for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++) {
+ if (key != SIDE_KEY_MATCH_ALL && side_cb->key != SIDE_KEY_MATCH_ALL && side_cb->key != key)
+ continue;
+ side_cb->u.call(es0->desc, side_arg_vec, side_cb->priv);
+ }
+ side_rcu_read_end(&event_rcu_gp, &rcu_read_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, SIDE_KEY_MATCH_ALL);
+}
+
+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,
+ uint64_t 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;
+
+ if (side_unlikely(finalized))
+ return;
+ if (side_unlikely(!initialized))
+ side_init();
+ if (side_unlikely(event_state->version != 0))
+ abort();
+ 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_SHARED_MASK)) {
+ if ((enabled & SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK) &&
+ (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_USER_EVENT)) {
+ // TODO: call kernel write.
+ }
+ if ((enabled & SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK) &&
+ (key == SIDE_KEY_MATCH_ALL || key == SIDE_KEY_PTRACE))
+ side_ptrace_hook(event_state, side_arg_vec, var_struct);
+ }
+ side_rcu_read_begin(&event_rcu_gp, &rcu_read_state);
+ for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++) {
+ if (key != SIDE_KEY_MATCH_ALL && side_cb->key != SIDE_KEY_MATCH_ALL && side_cb->key != key)
+ continue;
+ side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv);
+ }
+ side_rcu_read_end(&event_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, SIDE_KEY_MATCH_ALL);
+}
+
+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, uint64_t key)
+{
+ struct side_event_state *event_state = side_ptr_get(desc->state);
+ const struct side_event_state_0 *es0;
+ const struct side_callback *cb;
+
+ 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;
+}
+
+static
+int _side_tracer_callback_register(struct side_event_description *desc,
+ void *call, void *priv, uint64_t 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;
+
+ if (!call)
+ return SIDE_ERROR_INVAL;
+ if (finalized)
+ return SIDE_ERROR_EXITING;
+ if (!initialized)
+ side_init();
+ pthread_mutex_lock(&side_event_lock);
+ event_state = side_ptr_get(desc->state);
+ 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, key)) {
+ ret = SIDE_ERROR_EXIST;
+ goto unlock;
+ }
+ 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) {
+ ret = SIDE_ERROR_NOMEM;
+ goto unlock;
+ }
+ memcpy(new_cb, old_cb, old_nr_cb);
+ if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
+ new_cb[old_nr_cb].u.call_variadic =
+ (side_tracer_callback_variadic_func) call;
+ else
+ new_cb[old_nr_cb].u.call =
+ (side_tracer_callback_func) call;
+ new_cb[old_nr_cb].priv = priv;
+ 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(&event_rcu_gp);
+ if (old_nr_cb)
+ free(old_cb);
+ es0->nr_callbacks++;
+ /* Increment concurrently with kernel setting the top bits. */
+ if (!old_nr_cb)
+ (void) __atomic_add_fetch(&es0->enabled, 1, __ATOMIC_RELAXED);
+unlock:
+ pthread_mutex_unlock(&side_event_lock);
+ return ret;
+}
+
+int side_tracer_callback_register(struct side_event_description *desc,
+ side_tracer_callback_func call,
+ void *priv, uint64_t key)
+{
+ if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
+ return SIDE_ERROR_INVAL;
+ 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, uint64_t key)
+{
+ if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
+ return SIDE_ERROR_INVAL;
+ 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, uint64_t 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;
+
+ if (!call)
+ return SIDE_ERROR_INVAL;
+ if (finalized)
+ return SIDE_ERROR_EXITING;
+ if (!initialized)
+ side_init();
+ pthread_mutex_lock(&side_event_lock);
+ event_state = side_ptr_get(desc->state);
+ 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 = 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 - 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));
+ if (!new_cb) {
+ ret = SIDE_ERROR_NOMEM;
+ goto unlock;
+ }
+ memcpy(new_cb, old_cb, pos_idx);
+ memcpy(&new_cb[pos_idx], &old_cb[pos_idx + 1], old_nr_cb - pos_idx - 1);
+ }
+ /* High order bits are already zeroed. */
+ side_rcu_assign_pointer(es0->callbacks, new_cb);
+ side_rcu_wait_grace_period(&event_rcu_gp);
+ free(old_cb);
+ es0->nr_callbacks--;
+ /* Decrement concurrently with kernel setting the top bits. */
+ if (old_nr_cb == 1)
+ (void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
+unlock:
+ pthread_mutex_unlock(&side_event_lock);
+ return ret;
+}
+
+int side_tracer_callback_unregister(struct side_event_description *desc,
+ side_tracer_callback_func call,
+ void *priv, uint64_t key)
+{
+ if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
+ return SIDE_ERROR_INVAL;
+ 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, uint64_t key)
+{
+ if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
+ return SIDE_ERROR_INVAL;
+ 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)
+{
+ struct side_events_register_handle *events_handle = NULL;
+ struct side_tracer_handle *tracer_handle;
+
+ if (finalized)
+ return NULL;
+ if (!initialized)
+ side_init();
+ events_handle = (struct side_events_register_handle *)
+ calloc(1, sizeof(struct side_events_register_handle));
+ if (!events_handle)
+ return NULL;
+ events_handle->events = events;
+ events_handle->nr_events = nr_events;
+
+ pthread_mutex_lock(&side_event_lock);
+ side_list_insert_node_tail(&side_events_list, &events_handle->node);
+ side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
+ tracer_handle->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
+ events, nr_events, tracer_handle->priv);
+ }
+ pthread_mutex_unlock(&side_event_lock);
+ //TODO: call event batch register ioctl
+ return events_handle;
+}
+
+static
+void side_event_remove_callbacks(struct side_event_description *desc)
+{
+ struct side_event_state *event_state = side_ptr_get(desc->state);
+ 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 *) 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.
+ */
+ es0->nr_callbacks = 0;
+ side_rcu_assign_pointer(es0->callbacks, &side_empty_callback);
+ /*
+ * No need to wait for grace period because instrumentation is
+ * unreachable.
+ */
+ free(old_cb);
+}
+
+/*
+ * Unregister event handle. At this point, all side events in that
+ * handle should be unreachable.
+ */
+void side_events_unregister(struct side_events_register_handle *events_handle)
+{
+ struct side_tracer_handle *tracer_handle;
+ uint32_t i;
+
+ if (!events_handle)
+ return;
+ if (finalized)
+ return;
+ if (!initialized)
+ side_init();
+ pthread_mutex_lock(&side_event_lock);
+ side_list_remove_node(&events_handle->node);
+ side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
+ tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
+ events_handle->events, events_handle->nr_events,
+ tracer_handle->priv);
+ }
+ for (i = 0; i < events_handle->nr_events; i++) {
+ struct side_event_description *event = events_handle->events[i];
+
+ /* Skip NULL pointers */
+ if (!event)
+ continue;
+ side_event_remove_callbacks(event);
+ }
+ pthread_mutex_unlock(&side_event_lock);
+ //TODO: call event batch unregister ioctl
+ free(events_handle);
+}
+
+struct side_tracer_handle *side_tracer_event_notification_register(
+ void (*cb)(enum side_tracer_notification notif,
+ struct side_event_description **events, uint32_t nr_events, void *priv),
+ void *priv)
+{
+ struct side_tracer_handle *tracer_handle;
+ struct side_events_register_handle *events_handle;
+
+ if (finalized)
+ return NULL;
+ if (!initialized)
+ side_init();
+ tracer_handle = (struct side_tracer_handle *)
+ calloc(1, sizeof(struct side_tracer_handle));
+ if (!tracer_handle)
+ return NULL;
+ pthread_mutex_lock(&side_event_lock);
+ tracer_handle->cb = cb;
+ tracer_handle->priv = priv;
+ side_list_insert_node_tail(&side_tracer_list, &tracer_handle->node);
+ side_list_for_each_entry(events_handle, &side_events_list, node) {
+ cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
+ events_handle->events, events_handle->nr_events, priv);
+ }
+ pthread_mutex_unlock(&side_event_lock);
+ return tracer_handle;
+}
+
+void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer_handle)
+{
+ struct side_events_register_handle *events_handle;
+
+ if (finalized)
+ return;
+ if (!initialized)
+ side_init();
+ pthread_mutex_lock(&side_event_lock);
+ side_list_for_each_entry(events_handle, &side_events_list, node) {
+ tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
+ events_handle->events, events_handle->nr_events,
+ tracer_handle->priv);
+ }
+ side_list_remove_node(&tracer_handle->node);
+ pthread_mutex_unlock(&side_event_lock);
+ free(tracer_handle);
+}
+
+/* Called with side_statedump_lock held. */
+static
+void queue_statedump_pending(struct side_statedump_request_handle *handle, uint64_t key)
{
- if (side_unlikely(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) {
- printf("ERROR: unexpected variadic event description\n");
+ struct side_statedump_notification *notif;
+
+ notif = (struct side_statedump_notification *) calloc(1, sizeof(struct side_statedump_notification));
+ if (!notif)
abort();
+ notif->key = key;
+ side_list_insert_node_tail(&handle->notification_queue, ¬if->node);
+ if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) {
+ (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_HANDLE_REQUEST, __ATOMIC_SEQ_CST);
+ pthread_cond_broadcast(&statedump_agent_thread.worker_cond);
+ }
+}
+
+/* Called with side_statedump_lock held. */
+static
+void unqueue_statedump_pending(struct side_statedump_request_handle *handle, uint64_t key)
+{
+ struct side_statedump_notification *notif, *tmp;
+
+ side_list_for_each_entry_safe(notif, tmp, &handle->notification_queue, node) {
+ if (key == SIDE_KEY_MATCH_ALL || key == notif->key) {
+ side_list_remove_node(¬if->node);
+ free(notif);
+ }
+ }
+}
+
+static
+void side_statedump_run(struct side_statedump_request_handle *handle,
+ struct side_statedump_notification *notif)
+{
+ /* Invoke the state dump callback specifically for the tracer key. */
+ filter_key = notif->key;
+ side_statedump_event_call(side_statedump_begin,
+ side_arg_list(side_arg_string(handle->name)));
+ handle->cb();
+ side_statedump_event_call(side_statedump_end,
+ side_arg_list(side_arg_string(handle->name)));
+ filter_key = SIDE_KEY_MATCH_ALL;
+}
+
+static
+void _side_statedump_run_pending_requests(struct side_statedump_request_handle *handle)
+{
+ struct side_statedump_notification *notif, *tmp;
+ DEFINE_SIDE_LIST_HEAD(tmp_head);
+
+ pthread_mutex_lock(&side_statedump_lock);
+ side_list_splice(&handle->notification_queue, &tmp_head);
+ side_list_head_init(&handle->notification_queue);
+ pthread_mutex_unlock(&side_statedump_lock);
+
+ /* We are now sole owner of the tmp_head list. */
+ side_list_for_each_entry(notif, &tmp_head, node)
+ side_statedump_run(handle, notif);
+ side_list_for_each_entry_safe(notif, tmp, &tmp_head, node)
+ free(notif);
+
+ if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) {
+ pthread_mutex_lock(&side_statedump_lock);
+ pthread_cond_broadcast(&statedump_agent_thread.waiter_cond);
+ pthread_mutex_unlock(&side_statedump_lock);
+ }
+}
+
+static
+void *statedump_agent_func(void *arg __attribute__((unused)))
+{
+ for (;;) {
+ struct side_statedump_request_handle *handle;
+ struct side_rcu_read_state rcu_read_state;
+ enum agent_thread_state state;
+
+ pthread_mutex_lock(&side_statedump_lock);
+ for (;;) {
+ state = __atomic_load_n(&statedump_agent_thread.state, __ATOMIC_SEQ_CST);
+ if (state == AGENT_THREAD_STATE_BLOCKED)
+ pthread_cond_wait(&statedump_agent_thread.worker_cond, &side_statedump_lock);
+ else
+ break;
+ }
+ pthread_mutex_unlock(&side_statedump_lock);
+ if (state & AGENT_THREAD_STATE_EXIT)
+ break;
+ if (state & AGENT_THREAD_STATE_PAUSE) {
+ int attempt = 0;
+
+ (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_PAUSE_ACK, __ATOMIC_SEQ_CST);
+ for (;;) {
+ state = __atomic_load_n(&statedump_agent_thread.state, __ATOMIC_SEQ_CST);
+ if (!(state & AGENT_THREAD_STATE_PAUSE))
+ break;
+ if (attempt > SIDE_RETRY_BUSY_LOOP_ATTEMPTS) {
+ (void)poll(NULL, 0, SIDE_RETRY_DELAY_MS);
+ continue;
+ }
+ attempt++;
+ side_cpu_relax();
+ }
+ continue;
+ }
+ (void)__atomic_and_fetch(&statedump_agent_thread.state, ~AGENT_THREAD_STATE_HANDLE_REQUEST, __ATOMIC_SEQ_CST);
+ side_rcu_read_begin(&statedump_rcu_gp, &rcu_read_state);
+ side_list_for_each_entry_rcu(handle, &side_statedump_list, node)
+ _side_statedump_run_pending_requests(handle);
+ side_rcu_read_end(&statedump_rcu_gp, &rcu_read_state);
+ }
+ return NULL;
+}
+
+static
+void statedump_agent_thread_init(void)
+{
+ pthread_cond_init(&statedump_agent_thread.worker_cond, NULL);
+ pthread_cond_init(&statedump_agent_thread.waiter_cond, NULL);
+ statedump_agent_thread.state = AGENT_THREAD_STATE_BLOCKED;
+}
+
+/* Called with side_agent_thread_lock and side_statedump_lock held. */
+static
+void statedump_agent_thread_get(void)
+{
+ int ret;
+
+ if (statedump_agent_thread.ref++)
+ return;
+ statedump_agent_thread_init();
+ ret = pthread_create(&statedump_agent_thread.id, NULL,
+ statedump_agent_func, NULL);
+ if (ret) {
+ abort();
+ }
+}
+
+/*
+ * Called with side_agent_thread_lock and side_statedump_lock held.
+ * Returns true if join for agent thread is needed.
+ */
+static
+bool statedump_agent_thread_put(void)
+{
+ if (--statedump_agent_thread.ref)
+ return false;
+ (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_EXIT, __ATOMIC_SEQ_CST);
+ pthread_cond_broadcast(&statedump_agent_thread.worker_cond);
+ return true;
+}
+
+static
+void statedump_agent_thread_fini(void)
+{
+ statedump_agent_thread.state = AGENT_THREAD_STATE_BLOCKED;
+ if (pthread_cond_destroy(&statedump_agent_thread.worker_cond))
+ abort();
+ if (pthread_cond_destroy(&statedump_agent_thread.waiter_cond))
+ abort();
+}
+
+/* Called with side_agent_thread_lock held. */
+static
+void statedump_agent_thread_join(void)
+{
+ int ret;
+ void *retval;
+
+ ret = pthread_join(statedump_agent_thread.id, &retval);
+ if (ret) {
+ abort();
+ }
+ statedump_agent_thread_fini();
+}
+
+struct side_statedump_request_handle *
+ side_statedump_request_notification_register(const char *state_name,
+ void (*statedump_cb)(void),
+ enum side_statedump_mode mode)
+{
+ struct side_statedump_request_handle *handle;
+ char *name;
+
+ if (finalized)
+ return NULL;
+ if (!initialized)
+ side_init();
+ /*
+ * The statedump request notification should not be registered
+ * from a notification callback.
+ */
+ assert(!filter_key);
+ handle = (struct side_statedump_request_handle *)
+ calloc(1, sizeof(struct side_statedump_request_handle));
+ if (!handle)
+ return NULL;
+ name = strdup(state_name);
+ if (!name)
+ goto name_nomem;
+ handle->cb = statedump_cb;
+ handle->name = name;
+ handle->mode = mode;
+ side_list_head_init(&handle->notification_queue);
+
+ if (mode == SIDE_STATEDUMP_MODE_AGENT_THREAD)
+ pthread_mutex_lock(&side_agent_thread_lock);
+ pthread_mutex_lock(&side_statedump_lock);
+ if (mode == SIDE_STATEDUMP_MODE_AGENT_THREAD)
+ statedump_agent_thread_get();
+ side_list_insert_node_tail_rcu(&side_statedump_list, &handle->node);
+ /* Queue statedump pending for all tracers. */
+ queue_statedump_pending(handle, SIDE_KEY_MATCH_ALL);
+ pthread_mutex_unlock(&side_statedump_lock);
+
+ if (mode == SIDE_STATEDUMP_MODE_AGENT_THREAD) {
+ pthread_mutex_unlock(&side_agent_thread_lock);
+
+ pthread_mutex_lock(&side_statedump_lock);
+ while (!side_list_empty(&handle->notification_queue))
+ pthread_cond_wait(&statedump_agent_thread.waiter_cond, &side_statedump_lock);
+ pthread_mutex_unlock(&side_statedump_lock);
}
- if (side_unlikely(*desc->enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
- // TODO: call kernel write.
+
+ return handle;
+
+name_nomem:
+ free(handle);
+ return NULL;
+}
+
+void side_statedump_request_notification_unregister(struct side_statedump_request_handle *handle)
+{
+ bool join = false;
+
+ if (finalized)
+ return;
+ if (!initialized)
+ side_init();
+ assert(!filter_key);
+
+ if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD)
+ pthread_mutex_lock(&side_agent_thread_lock);
+ pthread_mutex_lock(&side_statedump_lock);
+ unqueue_statedump_pending(handle, SIDE_KEY_MATCH_ALL);
+ side_list_remove_node_rcu(&handle->node);
+ if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD)
+ join = statedump_agent_thread_put();
+ pthread_mutex_unlock(&side_statedump_lock);
+ if (join)
+ statedump_agent_thread_join();
+ if (handle->mode == SIDE_STATEDUMP_MODE_AGENT_THREAD)
+ pthread_mutex_unlock(&side_agent_thread_lock);
+
+ side_rcu_wait_grace_period(&statedump_rcu_gp);
+ free(handle->name);
+ free(handle);
+}
+
+/* Returns true if the handle has pending statedump requests. */
+bool side_statedump_poll_pending_requests(struct side_statedump_request_handle *handle)
+{
+ bool ret;
+
+ if (handle->mode != SIDE_STATEDUMP_MODE_POLLING)
+ return false;
+ pthread_mutex_lock(&side_statedump_lock);
+ ret = !side_list_empty(&handle->notification_queue);
+ pthread_mutex_unlock(&side_statedump_lock);
+ return ret;
+}
+
+/*
+ * Only polling mode state dump handles allow application to explicitly handle the
+ * pending requests.
+ */
+int side_statedump_run_pending_requests(struct side_statedump_request_handle *handle)
+{
+ if (handle->mode != SIDE_STATEDUMP_MODE_POLLING)
+ return SIDE_ERROR_INVAL;
+ _side_statedump_run_pending_requests(handle);
+ return SIDE_ERROR_OK;
+}
+
+/*
+ * Request a state dump for tracer callbacks identified with "key".
+ */
+int side_tracer_statedump_request(uint64_t key)
+{
+ struct side_statedump_request_handle *handle;
+
+ if (key == SIDE_KEY_MATCH_ALL)
+ return SIDE_ERROR_INVAL;
+ pthread_mutex_lock(&side_statedump_lock);
+ side_list_for_each_entry(handle, &side_statedump_list, node)
+ queue_statedump_pending(handle, key);
+ pthread_mutex_lock(&side_statedump_lock);
+ return SIDE_ERROR_OK;
+}
+
+/*
+ * Cancel a statedump request.
+ */
+int side_tracer_statedump_request_cancel(uint64_t key)
+{
+ struct side_statedump_request_handle *handle;
+
+ if (key == SIDE_KEY_MATCH_ALL)
+ return SIDE_ERROR_INVAL;
+ pthread_mutex_lock(&side_statedump_lock);
+ side_list_for_each_entry(handle, &side_statedump_list, node)
+ unqueue_statedump_pending(handle, key);
+ pthread_mutex_lock(&side_statedump_lock);
+ return SIDE_ERROR_OK;
+}
+
+/*
+ * Tracer keys are represented on 64-bit. Return SIDE_ERROR_NOMEM on
+ * overflow (which should never happen in practice).
+ */
+int side_tracer_request_key(uint64_t *key)
+{
+ int ret = SIDE_ERROR_OK;
+
+ pthread_mutex_lock(&side_key_lock);
+ if (side_key_next == 0) {
+ ret = SIDE_ERROR_NOMEM;
+ goto end;
}
- //TODO: replace tracer_call by rcu iteration on list of registered callbacks
- tracer_call(desc, sav_desc, NULL);
+ *key = side_key_next++;
+end:
+ pthread_mutex_unlock(&side_key_lock);
+ return ret;
+}
+
+/*
+ * Use of pthread_atfork depends on glibc 2.24 to eliminate hangs when
+ * waiting for the agent thread if the agent thread calls malloc. This
+ * is corrected by GNU libc
+ * commit 8a727af925be63aa6ea0f5f90e16751fd541626b.
+ * Ref. https://bugzilla.redhat.com/show_bug.cgi?id=906468
+ */
+static
+void side_before_fork(void)
+{
+ int attempt = 0;
+
+ pthread_mutex_lock(&side_agent_thread_lock);
+ if (!statedump_agent_thread.ref)
+ return;
+ /* Pause agent thread. */
+ pthread_mutex_lock(&side_statedump_lock);
+ (void)__atomic_or_fetch(&statedump_agent_thread.state, AGENT_THREAD_STATE_PAUSE, __ATOMIC_SEQ_CST);
+ pthread_cond_broadcast(&statedump_agent_thread.worker_cond);
+ pthread_mutex_unlock(&side_statedump_lock);
+ /* Wait for agent thread acknowledge. */
+ while (!(__atomic_load_n(&statedump_agent_thread.state, __ATOMIC_SEQ_CST) & AGENT_THREAD_STATE_PAUSE_ACK)) {
+ if (attempt > SIDE_RETRY_BUSY_LOOP_ATTEMPTS) {
+ (void)poll(NULL, 0, SIDE_RETRY_DELAY_MS);
+ continue;
+ }
+ attempt++;
+ side_cpu_relax();
+ }
+}
+
+static
+void side_after_fork_parent(void)
+{
+ if (statedump_agent_thread.ref)
+ (void)__atomic_and_fetch(&statedump_agent_thread.state,
+ ~(AGENT_THREAD_STATE_PAUSE | AGENT_THREAD_STATE_PAUSE_ACK),
+ __ATOMIC_SEQ_CST);
+ pthread_mutex_unlock(&side_agent_thread_lock);
}
-void side_call_variadic(const struct side_event_description *desc,
- const struct side_arg_vec_description *sav_desc,
- const struct side_arg_dynamic_event_struct *var_struct)
+/*
+ * The agent thread does not exist in the child process after a fork.
+ * Re-initialize its data structures and create a new agent thread.
+ */
+static
+void side_after_fork_child(void)
{
- if (side_unlikely(*desc->enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
- // TODO: call kernel write.
+ if (statedump_agent_thread.ref) {
+ int ret;
+
+ statedump_agent_thread_fini();
+ statedump_agent_thread_init();
+ ret = pthread_create(&statedump_agent_thread.id, NULL,
+ statedump_agent_func, NULL);
+ if (ret) {
+ abort();
+ }
}
- //TODO: replace tracer_call by rcu iteration on list of registered callbacks
- tracer_call_variadic(desc, sav_desc, var_struct, NULL);
+ pthread_mutex_unlock(&side_agent_thread_lock);
+}
+
+void side_init(void)
+{
+ if (initialized)
+ return;
+ side_rcu_gp_init(&event_rcu_gp);
+ side_rcu_gp_init(&statedump_rcu_gp);
+ if (pthread_atfork(side_before_fork, side_after_fork_parent, side_after_fork_child))
+ abort();
+ initialized = true;
+}
+
+/*
+ * side_exit() is executed from a library destructor. It can be called
+ * explicitly at application exit as well. Concurrent side API use is
+ * not expected at that point.
+ */
+void side_exit(void)
+{
+ struct side_events_register_handle *handle, *tmp;
+
+ if (finalized)
+ return;
+ side_list_for_each_entry_safe(handle, tmp, &side_events_list, node)
+ side_events_unregister(handle);
+ side_rcu_gp_exit(&event_rcu_gp);
+ side_rcu_gp_exit(&statedump_rcu_gp);
+ finalized = true;
}
projects / libside.git / blobdiff