X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fnotification-thread-events.c;h=6ba6a2e603d01ad3c5a2fffc116b5f006b654870;hp=e20c476f830342612721dfb0f5d93c9474b80e08;hb=2ae99f0b1ce4b1ae352a7bf179b1f040111afd46;hpb=7c2551ef99cb5b7a927373a198013601ee43fd9a diff --git a/src/bin/lttng-sessiond/notification-thread-events.c b/src/bin/lttng-sessiond/notification-thread-events.c index e20c476f8..6ba6a2e60 100644 --- a/src/bin/lttng-sessiond/notification-thread-events.c +++ b/src/bin/lttng-sessiond/notification-thread-events.c @@ -19,9 +19,6 @@ #include #include -#include "notification-thread.h" -#include "notification-thread-events.h" -#include "notification-thread-commands.h" #include #include #include @@ -36,10 +33,18 @@ #include #include #include + #include #include #include #include +#include + +#include "notification-thread.h" +#include "notification-thread-events.h" +#include "notification-thread-commands.h" +#include "lttng-sessiond.h" +#include "kernel.h" #define CLIENT_POLL_MASK_IN (LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP) #define CLIENT_POLL_MASK_IN_OUT (CLIENT_POLL_MASK_IN | LPOLLOUT) @@ -83,7 +88,7 @@ struct notification_client { uid_t uid; gid_t gid; /* - * Indicates if the credentials and versions of the client has been + * Indicates if the credentials and versions of the client have been * checked. */ bool validated; @@ -96,6 +101,11 @@ struct notification_client { struct cds_lfht_node client_socket_ht_node; struct { struct { + /* + * During the reception of a message, the reception + * buffers' "size" is set to contain the current + * message's complete payload. + */ struct lttng_dynamic_buffer buffer; /* Bytes left to receive for the current message. */ size_t bytes_to_receive; @@ -105,12 +115,13 @@ struct notification_client { * Indicates whether or not credentials are expected * from the client. */ - bool receive_creds; + bool expect_creds; /* * Indicates whether or not credentials were received * from the client. */ bool creds_received; + /* Only used during credentials reception. */ lttng_sock_cred creds; } inbound; struct { @@ -143,6 +154,20 @@ struct channel_state_sample { uint64_t lowest_usage; }; +static unsigned long hash_channel_key(struct channel_key *key); +static int evaluate_condition(struct lttng_condition *condition, + struct lttng_evaluation **evaluation, + struct notification_thread_state *state, + struct channel_state_sample *previous_sample, + struct channel_state_sample *latest_sample, + uint64_t buffer_capacity); +static +int send_evaluation_to_clients(struct lttng_trigger *trigger, + struct lttng_evaluation *evaluation, + struct notification_client_list *client_list, + struct notification_thread_state *state, + uid_t channel_uid, gid_t channel_gid); + static int match_client(struct cds_lfht_node *node, const void *key) { @@ -297,6 +322,16 @@ unsigned long lttng_condition_hash(struct lttng_condition *condition) } } +static +unsigned long hash_channel_key(struct channel_key *key) +{ + unsigned long key_hash = hash_key_u64(&key->key, lttng_ht_seed); + unsigned long domain_hash = hash_key_ulong( + (void *) (unsigned long) key->domain, lttng_ht_seed); + + return key_hash ^ domain_hash; +} + static void channel_info_destroy(struct channel_info *channel_info) { @@ -346,6 +381,126 @@ error: return NULL; } +/* This function must be called with the RCU read lock held. */ +static +int evaluate_condition_for_client(struct lttng_trigger *trigger, + struct lttng_condition *condition, + struct notification_client *client, + struct notification_thread_state *state) +{ + int ret; + struct cds_lfht_iter iter; + struct cds_lfht_node *node; + struct channel_info *channel_info = NULL; + struct channel_key *channel_key = NULL; + struct channel_state_sample *last_sample = NULL; + struct lttng_channel_trigger_list *channel_trigger_list = NULL; + struct lttng_evaluation *evaluation = NULL; + struct notification_client_list client_list = { 0 }; + struct notification_client_list_element client_list_element = { 0 }; + + assert(trigger); + assert(condition); + assert(client); + assert(state); + + /* Find the channel associated with the trigger. */ + cds_lfht_for_each_entry(state->channel_triggers_ht, &iter, + channel_trigger_list , channel_triggers_ht_node) { + struct lttng_trigger_list_element *element; + + cds_list_for_each_entry(element, &channel_trigger_list->list, node) { + struct lttng_condition *current_condition = + lttng_trigger_get_condition( + element->trigger); + + assert(current_condition); + if (!lttng_condition_is_equal(condition, + current_condition)) { + continue; + } + + /* Found the trigger, save the channel key. */ + channel_key = &channel_trigger_list->channel_key; + break; + } + if (channel_key) { + /* The channel key was found stop iteration. */ + break; + } + } + + if (!channel_key){ + /* No channel found; normal exit. */ + DBG("[notification-thread] No channel associated with newly subscribed-to condition"); + ret = 0; + goto end; + } + + /* Fetch channel info for the matching channel. */ + cds_lfht_lookup(state->channels_ht, + hash_channel_key(channel_key), + match_channel_info, + channel_key, + &iter); + node = cds_lfht_iter_get_node(&iter); + assert(node); + channel_info = caa_container_of(node, struct channel_info, + channels_ht_node); + + /* Retrieve the channel's last sample, if it exists. */ + cds_lfht_lookup(state->channel_state_ht, + hash_channel_key(channel_key), + match_channel_state_sample, + channel_key, + &iter); + node = cds_lfht_iter_get_node(&iter); + if (node) { + last_sample = caa_container_of(node, + struct channel_state_sample, + channel_state_ht_node); + } else { + /* Nothing to evaluate, no sample was ever taken. Normal exit */ + DBG("[notification-thread] No channel sample associated with newly subscribed-to condition"); + ret = 0; + goto end; + } + + ret = evaluate_condition(condition, &evaluation, state, NULL, + last_sample, channel_info->capacity); + if (ret) { + WARN("[notification-thread] Fatal error occurred while evaluating a newly subscribed-to condition"); + goto end; + } + + if (!evaluation) { + /* Evaluation yielded nothing. Normal exit. */ + DBG("[notification-thread] Newly subscribed-to condition evaluated to false, nothing to report to client"); + ret = 0; + goto end; + } + + /* + * Create a temporary client list with the client currently + * subscribing. + */ + cds_lfht_node_init(&client_list.notification_trigger_ht_node); + CDS_INIT_LIST_HEAD(&client_list.list); + client_list.trigger = trigger; + + CDS_INIT_LIST_HEAD(&client_list_element.node); + client_list_element.client = client; + cds_list_add(&client_list_element.node, &client_list.list); + + /* Send evaluation result to the newly-subscribed client. */ + DBG("[notification-thread] Newly subscribed-to condition evaluated to true, notifying client"); + ret = send_evaluation_to_clients(trigger, evaluation, &client_list, + state, channel_info->uid, channel_info->gid); + +end: + return ret; +} + static int notification_thread_client_subscribe(struct notification_client *client, struct lttng_condition *condition, @@ -393,11 +548,6 @@ int notification_thread_client_subscribe(struct notification_client *client, condition_list_element->condition = condition; cds_list_add(&condition_list_element->node, &client->condition_list); - /* - * Add the client to the list of clients interested in a given trigger - * if a "notification" trigger with a corresponding condition was - * added prior. - */ cds_lfht_lookup(state->notification_trigger_clients_ht, lttng_condition_hash(condition), match_client_list_condition, @@ -405,12 +555,34 @@ int notification_thread_client_subscribe(struct notification_client *client, &iter); node = cds_lfht_iter_get_node(&iter); if (!node) { + /* + * No notification-emiting trigger registered with this + * condition. We don't evaluate the condition right away + * since this trigger is not registered yet. + */ free(client_list_element); goto end_unlock; } client_list = caa_container_of(node, struct notification_client_list, notification_trigger_ht_node); + /* + * The condition to which the client just subscribed is evaluated + * at this point so that conditions that are already TRUE result + * in a notification being sent out. + */ + if (evaluate_condition_for_client(client_list->trigger, condition, + client, state)) { + WARN("[notification-thread] Evaluation of a condition on client subscription failed, aborting."); + ret = -1; + goto end_unlock; + } + + /* + * Add the client to the list of clients interested in a given trigger + * if a "notification" trigger with a corresponding condition was + * added prior. + */ client_list_element->client = client; CDS_INIT_LIST_HEAD(&client_list_element->node); cds_list_add(&client_list_element->node, &client_list->list); @@ -631,13 +803,6 @@ bool trigger_applies_to_client(struct lttng_trigger *trigger, return applies; } -static -unsigned long hash_channel_key(struct channel_key *key) -{ - return hash_key_u64(&key->key, lttng_ht_seed) ^ hash_key_ulong( - (void *) (unsigned long) key->domain, lttng_ht_seed); -} - static int handle_notification_thread_command_add_channel( struct notification_thread_state *state, @@ -799,15 +964,60 @@ end: return 0; } +static +int condition_is_supported(struct lttng_condition *condition) +{ + int ret; + + switch (lttng_condition_get_type(condition)) { + case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW: + case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH: + { + enum lttng_domain_type domain; + + ret = lttng_condition_buffer_usage_get_domain_type(condition, + &domain); + if (ret) { + ret = -1; + goto end; + } + + if (domain != LTTNG_DOMAIN_KERNEL) { + ret = 1; + goto end; + } + + /* + * Older kernel tracers don't expose the API to monitor their + * buffers. Therefore, we reject triggers that require that + * mechanism to be available to be evaluated. + */ + ret = kernel_supports_ring_buffer_snapshot_sample_positions( + kernel_tracer_fd); + break; + } + default: + ret = 1; + } +end: + return ret; +} + /* * FIXME A client's credentials are not checked when registering a trigger, nor * are they stored alongside with the trigger. * - * The effects of this are benign: + * The effects of this are benign since: * - The client will succeed in registering the trigger, as it is valid, * - The trigger will, internally, be bound to the channel, * - The notifications will not be sent since the client's credentials * are checked against the channel at that moment. + * + * If this function returns a non-zero value, it means something is + * fundamentally and the whole subsystem/thread will be torn down. + * + * If a non-fatal error occurs, just set the cmd_result to the appropriate + * error code. */ static int handle_notification_thread_command_register_trigger( @@ -829,6 +1039,19 @@ int handle_notification_thread_command_register_trigger( rcu_read_lock(); condition = lttng_trigger_get_condition(trigger); + assert(condition); + + ret = condition_is_supported(condition); + if (ret < 0) { + goto error; + } else if (ret == 0) { + *cmd_result = LTTNG_ERR_NOT_SUPPORTED; + goto error; + } else { + /* Feature is supported, continue. */ + ret = 0; + } + trigger_ht_element = zmalloc(sizeof(*trigger_ht_element)); if (!trigger_ht_element) { ret = -1; @@ -891,11 +1114,6 @@ int handle_notification_thread_command_register_trigger( cds_lfht_add(state->notification_trigger_clients_ht, lttng_condition_hash(condition), &client_list->notification_trigger_ht_node); - /* - * Client list ownership transferred to the - * notification_trigger_clients_ht. - */ - client_list = NULL; /* * Add the trigger to list of triggers bound to the channels currently @@ -917,7 +1135,6 @@ int handle_notification_thread_command_register_trigger( &iter); node = cds_lfht_iter_get_node(&iter); assert(node); - /* Free the list of triggers associated with this channel. */ trigger_list = caa_container_of(node, struct lttng_channel_trigger_list, channel_triggers_ht_node); @@ -930,10 +1147,52 @@ int handle_notification_thread_command_register_trigger( CDS_INIT_LIST_HEAD(&trigger_list_element->node); trigger_list_element->trigger = trigger; cds_list_add(&trigger_list_element->node, &trigger_list->list); + /* A trigger can only apply to one channel. */ break; } + /* + * Since there is nothing preventing clients from subscribing to a + * condition before the corresponding trigger is registered, we have + * to evaluate this new condition right away. + * + * At some point, we were waiting for the next "evaluation" (e.g. on + * reception of a channel sample) to evaluate this new condition, but + * that was broken. + * + * The reason it was broken is that waiting for the next sample + * does not allow us to properly handle transitions for edge-triggered + * conditions. + * + * Consider this example: when we handle a new channel sample, we + * evaluate each conditions twice: once with the previous state, and + * again with the newest state. We then use those two results to + * determine whether a state change happened: a condition was false and + * became true. If a state change happened, we have to notify clients. + * + * Now, if a client subscribes to a given notification and registers + * a trigger *after* that subscription, we have to make sure the + * condition is evaluated at this point while considering only the + * current state. Otherwise, the next evaluation cycle may only see + * that the evaluations remain the same (true for samples n-1 and n) and + * the client will never know that the condition has been met. + */ + cds_list_for_each_entry_safe(client_list_element, tmp, + &client_list->list, node) { + ret = evaluate_condition_for_client(trigger, condition, + client_list_element->client, state); + if (ret) { + goto error_free_client_list; + } + } + + /* + * Client list ownership transferred to the + * notification_trigger_clients_ht. + */ + client_list = NULL; + *cmd_result = LTTNG_OK; error_free_client_list: if (client_list) { @@ -957,6 +1216,7 @@ error: return ret; } +static int handle_notification_thread_command_unregister_trigger( struct notification_thread_state *state, struct lttng_trigger *trigger, @@ -1007,6 +1267,8 @@ int handle_notification_thread_command_unregister_trigger( DBG("[notification-thread] Removed trigger from channel_triggers_ht"); cds_list_del(&trigger_element->node); + /* A trigger can only appear once per channel */ + break; } } @@ -1059,7 +1321,7 @@ int handle_notification_thread_command( struct notification_thread_command *cmd; /* Read event_fd to put it back into a quiescent state. */ - ret = read(handle->cmd_queue.event_fd, &counter, sizeof(counter)); + ret = read(lttng_pipe_get_readfd(handle->cmd_queue.event_pipe), &counter, sizeof(counter)); if (ret == -1) { goto error; } @@ -1108,12 +1370,12 @@ int handle_notification_thread_command( } end: cds_list_del(&cmd->cmd_list_node); - futex_nto1_wake(&cmd->reply_futex); + lttng_waiter_wake_up(&cmd->reply_waiter); pthread_mutex_unlock(&handle->cmd_queue.lock); return ret; error_unlock: /* Wake-up and return a fatal error to the calling thread. */ - futex_nto1_wake(&cmd->reply_futex); + lttng_waiter_wake_up(&cmd->reply_waiter); pthread_mutex_unlock(&handle->cmd_queue.lock); cmd->reply_code = LTTNG_ERR_FATAL; error: @@ -1151,7 +1413,7 @@ end: } static -void client_reset_inbound_state(struct notification_client *client) +int client_reset_inbound_state(struct notification_client *client) { int ret; @@ -1163,9 +1425,12 @@ void client_reset_inbound_state(struct notification_client *client) sizeof(struct lttng_notification_channel_message); client->communication.inbound.msg_type = LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNKNOWN; - client->communication.inbound.receive_creds = false; LTTNG_SOCK_SET_UID_CRED(&client->communication.inbound.creds, -1); LTTNG_SOCK_SET_GID_CRED(&client->communication.inbound.creds, -1); + ret = lttng_dynamic_buffer_set_size( + &client->communication.inbound.buffer, + client->communication.inbound.bytes_to_receive); + return ret; } int handle_notification_thread_client_connect( @@ -1185,7 +1450,13 @@ int handle_notification_thread_client_connect( CDS_INIT_LIST_HEAD(&client->condition_list); lttng_dynamic_buffer_init(&client->communication.inbound.buffer); lttng_dynamic_buffer_init(&client->communication.outbound.buffer); - client_reset_inbound_state(client); + client->communication.inbound.expect_creds = true; + ret = client_reset_inbound_state(client); + if (ret) { + ERR("[notification-thread] Failed to reset client communication's inbound state"); + ret = 0; + goto error; + } ret = lttcomm_accept_unix_sock(state->notification_channel_socket); if (ret < 0) { @@ -1220,7 +1491,6 @@ int handle_notification_thread_client_connect( DBG("[notification-thread] Added new notification channel client socket (%i) to poll set", client->socket); - /* Add to ht. */ rcu_read_lock(); cds_lfht_add(state->client_socket_ht, hash_client_socket(client->socket), @@ -1290,7 +1560,7 @@ int handle_notification_thread_client_disconnect_all( int handle_notification_thread_trigger_unregister_all( struct notification_thread_state *state) { - bool error_occured = false; + bool error_occurred = false; struct cds_lfht_iter iter; struct lttng_trigger_ht_element *trigger_ht_element; @@ -1299,10 +1569,10 @@ int handle_notification_thread_trigger_unregister_all( int ret = handle_notification_thread_command_unregister_trigger( state, trigger_ht_element->trigger, NULL); if (ret) { - error_occured = true; + error_occurred = true; } } - return error_occured ? -1 : 0; + return error_occurred ? -1 : 0; } static @@ -1475,12 +1745,8 @@ int client_dispatch_message(struct notification_client *client, client->communication.inbound.bytes_to_receive = msg->size; client->communication.inbound.msg_type = (enum lttng_notification_channel_message_type) msg->type; - if (client->communication.inbound.msg_type == - LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE) { - client->communication.inbound.receive_creds = true; - } ret = lttng_dynamic_buffer_set_size( - &client->communication.inbound.buffer, 0); + &client->communication.inbound.buffer, msg->size); if (ret) { goto end; } @@ -1508,7 +1774,7 @@ int client_dispatch_message(struct notification_client *client, handshake_client = (struct lttng_notification_channel_command_handshake *) client->communication.inbound.buffer.data; - client->major = handshake_client->major; + client->major = handshake_client->major; client->minor = handshake_client->minor; if (!client->communication.inbound.creds_received) { ERR("[notification-thread] No credentials received from client"); @@ -1547,7 +1813,11 @@ int client_dispatch_message(struct notification_client *client, } /* Set reception state to receive the next message header. */ - client_reset_inbound_state(client); + ret = client_reset_inbound_state(client); + if (ret) { + ERR("[notification-thread] Failed to reset client communication's inbound state"); + goto end; + } client->validated = true; break; } @@ -1594,7 +1864,11 @@ int client_dispatch_message(struct notification_client *client, } /* Set reception state to receive the next message header. */ - client_reset_inbound_state(client); + ret = client_reset_inbound_state(client); + if (ret) { + ERR("[notification-thread] Failed to reset client communication's inbound state"); + goto end; + } break; } default: @@ -1608,7 +1882,7 @@ end: int handle_notification_thread_client_in( struct notification_thread_state *state, int socket) { - int ret; + int ret = 0; struct notification_client *client; ssize_t recv_ret; size_t offset; @@ -1620,21 +1894,15 @@ int handle_notification_thread_client_in( goto end; } - offset = client->communication.inbound.buffer.size; - ret = lttng_dynamic_buffer_set_size( - &client->communication.inbound.buffer, - client->communication.inbound.bytes_to_receive); - if (ret) { - goto end; - } - - if (client->communication.inbound.receive_creds) { + offset = client->communication.inbound.buffer.size - + client->communication.inbound.bytes_to_receive; + if (client->communication.inbound.expect_creds) { recv_ret = lttcomm_recv_creds_unix_sock(socket, client->communication.inbound.buffer.data + offset, client->communication.inbound.bytes_to_receive, &client->communication.inbound.creds); if (recv_ret > 0) { - client->communication.inbound.receive_creds = false; + client->communication.inbound.expect_creds = false; client->communication.inbound.creds_received = true; } } else { @@ -1647,14 +1915,6 @@ int handle_notification_thread_client_in( } client->communication.inbound.bytes_to_receive -= recv_ret; - ret = lttng_dynamic_buffer_set_size( - &client->communication.inbound.buffer, - client->communication.inbound.buffer.size - - client->communication.inbound.bytes_to_receive); - if (ret) { - goto end; - } - if (client->communication.inbound.bytes_to_receive == 0) { ret = client_dispatch_message(client, state); if (ret) {