Implement PID tracking for kernel tracing
[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c
index 0b97ed61a1ec54fc928b1e5a69890ede4002a162..91ea88cb7c593a5c5f8cb010016a4f5f9816b8d4 100644 (file)
@@ -18,6 +18,7 @@
 #define _GNU_SOURCE
 #define _LGPL_SOURCE
 #include <assert.h>
+#include <string.h>
 #include <inttypes.h>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
@@ -220,7 +221,9 @@ static int list_lttng_agent_events(struct agent *agt,
 
        DBG3("Listing agent events");
 
+       rcu_read_lock();
        nb_event = lttng_ht_get_count(agt->events);
+       rcu_read_unlock();
        if (nb_event == 0) {
                ret = nb_event;
                goto error;
@@ -926,6 +929,90 @@ error:
        return ret;
 }
 
+/*
+ * Command LTTNG_TRACK_PID processed by the client thread.
+ */
+int cmd_track_pid(struct ltt_session *session, int domain, int pid)
+{
+       int ret;
+
+       rcu_read_lock();
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+       {
+               struct ltt_kernel_session *ksess;
+
+               ksess = session->kernel_session;
+
+               ret = kernel_track_pid(ksess, pid);
+               if (ret != LTTNG_OK) {
+                       goto error;
+               }
+
+               kernel_wait_quiescent(kernel_tracer_fd);
+               break;
+       }
+#if 0
+       case LTTNG_DOMAIN_UST:
+       case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
+       case LTTNG_DOMAIN_UST_EXEC_NAME:
+       case LTTNG_DOMAIN_UST_PID:
+#endif
+       default:
+               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
+               goto error;
+       }
+
+       ret = LTTNG_OK;
+
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Command LTTNG_UNTRACK_PID processed by the client thread.
+ */
+int cmd_untrack_pid(struct ltt_session *session, int domain, int pid)
+{
+       int ret;
+
+       rcu_read_lock();
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+       {
+               struct ltt_kernel_session *ksess;
+
+               ksess = session->kernel_session;
+
+               ret = kernel_untrack_pid(ksess, pid);
+               if (ret != LTTNG_OK) {
+                       goto error;
+               }
+
+               kernel_wait_quiescent(kernel_tracer_fd);
+               break;
+       }
+#if 0
+       case LTTNG_DOMAIN_UST:
+       case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
+       case LTTNG_DOMAIN_UST_EXEC_NAME:
+       case LTTNG_DOMAIN_UST_PID:
+#endif
+       default:
+               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
+               goto error;
+       }
+
+       ret = LTTNG_OK;
+
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
 /*
  * Command LTTNG_ENABLE_CHANNEL processed by the client thread.
  *
@@ -937,11 +1024,21 @@ int cmd_enable_channel(struct ltt_session *session,
        int ret;
        struct ltt_ust_session *usess = session->ust_session;
        struct lttng_ht *chan_ht;
+       size_t len;
 
        assert(session);
        assert(attr);
        assert(domain);
 
+       len = strnlen(attr->name, sizeof(attr->name));
+
+       /* Validate channel name */
+       if (attr->name[0] == '.' ||
+               memchr(attr->name, '/', len) != NULL) {
+               ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
+               goto end;
+       }
+
        DBG("Enabling channel %s for session %s", attr->name, session->name);
 
        rcu_read_lock();
@@ -1022,6 +1119,7 @@ int cmd_enable_channel(struct ltt_session *session,
 
 error:
        rcu_read_unlock();
+end:
        return ret;
 }
 
@@ -1040,7 +1138,8 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
        event_name = event->name;
 
-       if (event->loglevel_type || event->loglevel || event->enabled
+       /* Error out on unhandled search criteria */
+       if (event->loglevel_type || event->loglevel != -1 || event->enabled
                        || event->pid || event->filter || event->exclusion) {
                return LTTNG_ERR_UNK;
        }
@@ -2004,13 +2103,12 @@ error:
 /*
  * Command LTTNG_SET_CONSUMER_URI processed by the client thread.
  */
-int cmd_set_consumer_uri(int domain, struct ltt_session *session,
-               size_t nb_uri, struct lttng_uri *uris)
+int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
+               struct lttng_uri *uris)
 {
        int ret, i;
        struct ltt_kernel_session *ksess = session->kernel_session;
        struct ltt_ust_session *usess = session->ust_session;
-       struct consumer_output *consumer = NULL;
 
        assert(session);
        assert(uris);
@@ -2022,41 +2120,41 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
                goto error;
        }
 
-       /*
-        * This case switch makes sure the domain session has a temporary consumer
-        * so the URL can be set.
-        */
-       switch (domain) {
-       case 0:
-               /* Code flow error. A session MUST always have a consumer object */
-               assert(session->consumer);
-               /*
-                * The URL will be added to the tracing session consumer instead of a
-                * specific domain consumer.
-                */
-               consumer = session->consumer;
-               break;
-       case LTTNG_DOMAIN_KERNEL:
-               /* Code flow error if we don't have a kernel session here. */
-               assert(ksess);
-               assert(ksess->consumer);
-               consumer = ksess->consumer;
-               break;
-       case LTTNG_DOMAIN_UST:
-               /* Code flow error if we don't have a kernel session here. */
-               assert(usess);
-               assert(usess->consumer);
-               consumer = usess->consumer;
-               break;
-       }
-
+       /* Set the "global" consumer URIs */
        for (i = 0; i < nb_uri; i++) {
-               ret = add_uri_to_consumer(consumer, &uris[i], domain, session->name);
+               ret = add_uri_to_consumer(session->consumer,
+                               &uris[i], 0, session->name);
                if (ret != LTTNG_OK) {
                        goto error;
                }
        }
 
+       /* Set UST session URIs */
+       if (session->ust_session) {
+               for (i = 0; i < nb_uri; i++) {
+                       ret = add_uri_to_consumer(
+                                       session->ust_session->consumer,
+                                       &uris[i], LTTNG_DOMAIN_UST,
+                                       session->name);
+                       if (ret != LTTNG_OK) {
+                               goto error;
+                       }
+               }
+       }
+
+       /* Set kernel session URIs */
+       if (session->kernel_session) {
+               for (i = 0; i < nb_uri; i++) {
+                       ret = add_uri_to_consumer(
+                                       session->kernel_session->consumer,
+                                       &uris[i], LTTNG_DOMAIN_KERNEL,
+                                       session->name);
+                       if (ret != LTTNG_OK) {
+                               goto error;
+                       }
+               }
+       }
+
        /*
         * Make sure to set the session in output mode after we set URI since a
         * session can be created without URL (thus flagged in no output mode).
@@ -2064,7 +2162,9 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
        session->output_traces = 1;
        if (ksess) {
                ksess->output_traces = 1;
-       } else if (usess) {
+       }
+
+       if (usess) {
                usess->output_traces = 1;
        }
 
@@ -2126,7 +2226,7 @@ int cmd_create_session_uri(char *name, struct lttng_uri *uris,
        }
 
        if (uris) {
-               ret = cmd_set_consumer_uri(0, session, nb_uri, uris);
+               ret = cmd_set_consumer_uri(session, nb_uri, uris);
                if (ret != LTTNG_OK) {
                        goto consumer_error;
                }
@@ -2415,12 +2515,14 @@ ssize_t cmd_list_domains(struct ltt_session *session,
                DBG3("Listing domains found UST global domain");
                nb_dom++;
 
+               rcu_read_lock();
                cds_lfht_for_each_entry(session->ust_session->agents->ht, &iter.iter,
                                agt, node.node) {
                        if (agt->being_used) {
                                nb_dom++;
                        }
                }
+               rcu_read_unlock();
        }
 
        if (!nb_dom) {
@@ -2443,6 +2545,7 @@ ssize_t cmd_list_domains(struct ltt_session *session,
                (*domains)[index].buf_type = session->ust_session->buffer_type;
                index++;
 
+               rcu_read_lock();
                cds_lfht_for_each_entry(session->ust_session->agents->ht, &iter.iter,
                                agt, node.node) {
                        if (agt->being_used) {
@@ -2451,6 +2554,7 @@ ssize_t cmd_list_domains(struct ltt_session *session,
                                index++;
                        }
                }
+               rcu_read_unlock();
        }
 end:
        return nb_dom;
@@ -2482,8 +2586,10 @@ ssize_t cmd_list_channels(int domain, struct ltt_session *session,
                break;
        case LTTNG_DOMAIN_UST:
                if (session->ust_session != NULL) {
+                       rcu_read_lock();
                        nb_chan = lttng_ht_get_count(
-                                       session->ust_session->domain_global.channels);
+                               session->ust_session->domain_global.channels);
+                       rcu_read_unlock();
                }
                DBG3("Number of UST global channels %zd", nb_chan);
                if (nb_chan < 0) {
@@ -2544,10 +2650,12 @@ ssize_t cmd_list_events(int domain, struct ltt_session *session,
                        struct lttng_ht_iter iter;
                        struct agent *agt;
 
+                       rcu_read_lock();
                        cds_lfht_for_each_entry(session->ust_session->agents->ht,
                                        &iter.iter, agt, node.node) {
                                nb_event = list_lttng_agent_events(agt, events);
                        }
+                       rcu_read_unlock();
                }
                break;
        default:
@@ -2918,7 +3026,7 @@ error:
  */
 static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
                struct snapshot_output *output, struct ltt_session *session,
-               int wait, uint64_t max_stream_size)
+               int wait, uint64_t nb_packets_per_stream)
 {
        int ret;
 
@@ -2949,17 +3057,19 @@ static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
                goto error_snapshot;
        }
 
-       ret = kernel_snapshot_record(ksess, output, wait, max_stream_size);
+       ret = kernel_snapshot_record(ksess, output, wait, nb_packets_per_stream);
        if (ret != LTTNG_OK) {
                goto error_snapshot;
        }
 
        ret = LTTNG_OK;
+       goto end;
 
 error_snapshot:
        /* Clean up copied sockets so this output can use some other later on. */
        consumer_destroy_output_sockets(output->consumer);
 error:
+end:
        return ret;
 }
 
@@ -2970,7 +3080,7 @@ error:
  */
 static int record_ust_snapshot(struct ltt_ust_session *usess,
                struct snapshot_output *output, struct ltt_session *session,
-               int wait, uint64_t max_stream_size)
+               int wait, uint64_t nb_packets_per_stream)
 {
        int ret;
 
@@ -3001,7 +3111,7 @@ static int record_ust_snapshot(struct ltt_ust_session *usess,
                goto error_snapshot;
        }
 
-       ret = ust_app_snapshot_record(usess, output, wait, max_stream_size);
+       ret = ust_app_snapshot_record(usess, output, wait, nb_packets_per_stream);
        if (ret < 0) {
                switch (-ret) {
                case EINVAL:
@@ -3026,69 +3136,90 @@ error:
        return ret;
 }
 
-/*
- * Return the biggest subbuffer size of all channels in the given session.
- */
-static uint64_t get_session_max_subbuf_size(struct ltt_session *session)
+static
+uint64_t get_session_size_one_more_packet_per_stream(struct ltt_session *session,
+       uint64_t cur_nr_packets)
 {
-       uint64_t max_size = 0;
-
-       assert(session);
+       uint64_t tot_size = 0;
 
        if (session->kernel_session) {
                struct ltt_kernel_channel *chan;
                struct ltt_kernel_session *ksess = session->kernel_session;
 
-               /*
-                * For each channel, add to the max size the size of each subbuffer
-                * multiplied by their sized.
-                */
                cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
-                       if (chan->channel->attr.subbuf_size > max_size) {
-                               max_size = chan->channel->attr.subbuf_size;
+                       if (cur_nr_packets >= chan->channel->attr.num_subbuf) {
+                               /*
+                                * Don't take channel into account if we
+                                * already grab all its packets.
+                                */
+                               continue;
                        }
+                       tot_size += chan->channel->attr.subbuf_size
+                               * chan->stream_count;
                }
        }
 
        if (session->ust_session) {
-               struct lttng_ht_iter iter;
-               struct ltt_ust_channel *uchan;
                struct ltt_ust_session *usess = session->ust_session;
 
-               rcu_read_lock();
-               cds_lfht_for_each_entry(usess->domain_global.channels->ht, &iter.iter,
-                               uchan, node.node) {
-                       if (uchan->attr.subbuf_size > max_size) {
-                               max_size = uchan->attr.subbuf_size;
-                       }
-               }
-               rcu_read_unlock();
+               tot_size += ust_app_get_size_one_more_packet_per_stream(usess,
+                               cur_nr_packets);
        }
 
-       return max_size;
+       return tot_size;
 }
 
 /*
- * Returns the total number of streams for a session or a negative value
- * on error.
+ * Calculate the number of packets we can grab from each stream that
+ * fits within the overall snapshot max size.
+ *
+ * Returns -1 on error, 0 means infinite number of packets, else > 0 is
+ * the number of packets per stream.
+ *
+ * TODO: this approach is not perfect: we consider the worse case
+ * (packet filling the sub-buffers) as an upper bound, but we could do
+ * better if we do this calculation while we actually grab the packet
+ * content: we would know how much padding we don't actually store into
+ * the file.
+ *
+ * This algorithm is currently bounded by the number of packets per
+ * stream.
+ *
+ * Since we call this algorithm before actually grabbing the data, it's
+ * an approximation: for instance, applications could appear/disappear
+ * in between this call and actually grabbing data.
  */
-static unsigned int get_session_nb_streams(struct ltt_session *session)
+static
+int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t max_size)
 {
-       unsigned int total_streams = 0;
+       int64_t size_left;
+       uint64_t cur_nb_packets = 0;
 
-       if (session->kernel_session) {
-               struct ltt_kernel_session *ksess = session->kernel_session;
-
-               total_streams += ksess->stream_count_global;
+       if (!max_size) {
+               return 0;       /* Infinite */
        }
 
-       if (session->ust_session) {
-               struct ltt_ust_session *usess = session->ust_session;
+       size_left = max_size;
+       for (;;) {
+               uint64_t one_more_packet_tot_size;
 
-               total_streams += ust_app_get_nb_stream(usess);
+               one_more_packet_tot_size = get_session_size_one_more_packet_per_stream(session,
+                                       cur_nb_packets);
+               if (!one_more_packet_tot_size) {
+                       /* We are already grabbing all packets. */
+                       break;
+               }
+               size_left -= one_more_packet_tot_size;
+               if (size_left < 0) {
+                       break;
+               }
+               cur_nb_packets++;
        }
-
-       return total_streams;
+       if (!cur_nb_packets) {
+               /* Not enough room to grab one packet of each stream, error. */
+               return -1;
+       }
+       return cur_nb_packets;
 }
 
 /*
@@ -3105,8 +3236,7 @@ int cmd_snapshot_record(struct ltt_session *session,
        int ret = LTTNG_OK;
        unsigned int use_tmp_output = 0;
        struct snapshot_output tmp_output;
-       unsigned int nb_streams, snapshot_success = 0;
-       uint64_t session_max_size = 0, max_stream_size = 0;
+       unsigned int snapshot_success = 0;
 
        assert(session);
        assert(output);
@@ -3146,44 +3276,20 @@ int cmd_snapshot_record(struct ltt_session *session,
                use_tmp_output = 1;
        }
 
-       /*
-        * Get the session maximum size for a snapshot meaning it will compute the
-        * size of all streams from all domain.
-        */
-       max_stream_size = get_session_max_subbuf_size(session);
-
-       nb_streams = get_session_nb_streams(session);
-       if (nb_streams) {
-               /*
-                * The maximum size of the snapshot is the number of streams multiplied
-                * by the biggest subbuf size of all channels in a session which is the
-                * maximum stream size available for each stream. The session max size
-                * is now checked against the snapshot max size value given by the user
-                * and if lower, an error is returned.
-                */
-               session_max_size = max_stream_size * nb_streams;
-       }
-
-       DBG3("Snapshot max size is %" PRIu64 " for max stream size of %" PRIu64,
-                       session_max_size, max_stream_size);
-
-       /*
-        * If we use a temporary output, check right away if the max size fits else
-        * for each output the max size will be checked.
-        */
-       if (use_tmp_output &&
-                       (tmp_output.max_size != 0 &&
-                       tmp_output.max_size < session_max_size)) {
-               ret = LTTNG_ERR_MAX_SIZE_INVALID;
-               goto error;
-       }
-
        if (session->kernel_session) {
                struct ltt_kernel_session *ksess = session->kernel_session;
 
                if (use_tmp_output) {
+                       int64_t nb_packets_per_stream;
+
+                       nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+                                       tmp_output.max_size);
+                       if (nb_packets_per_stream < 0) {
+                               ret = LTTNG_ERR_MAX_SIZE_INVALID;
+                               goto error;
+                       }
                        ret = record_kernel_snapshot(ksess, &tmp_output, session,
-                                       wait, max_stream_size);
+                                       wait, nb_packets_per_stream);
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
@@ -3195,6 +3301,8 @@ int cmd_snapshot_record(struct ltt_session *session,
                        rcu_read_lock();
                        cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
                                        &iter.iter, sout, node.node) {
+                               int64_t nb_packets_per_stream;
+
                                /*
                                 * Make a local copy of the output and assign the possible
                                 * temporary value given by the caller.
@@ -3202,14 +3310,13 @@ int cmd_snapshot_record(struct ltt_session *session,
                                memset(&tmp_output, 0, sizeof(tmp_output));
                                memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-                               /* Use temporary max size. */
                                if (output->max_size != (uint64_t) -1ULL) {
                                        tmp_output.max_size = output->max_size;
                                }
 
-                               if (tmp_output.max_size != 0 &&
-                                               tmp_output.max_size < session_max_size) {
-                                       rcu_read_unlock();
+                               nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+                                               tmp_output.max_size);
+                               if (nb_packets_per_stream < 0) {
                                        ret = LTTNG_ERR_MAX_SIZE_INVALID;
                                        goto error;
                                }
@@ -3223,7 +3330,7 @@ int cmd_snapshot_record(struct ltt_session *session,
                                tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
 
                                ret = record_kernel_snapshot(ksess, &tmp_output,
-                                               session, wait, max_stream_size);
+                                               session, wait, nb_packets_per_stream);
                                if (ret != LTTNG_OK) {
                                        rcu_read_unlock();
                                        goto error;
@@ -3238,8 +3345,16 @@ int cmd_snapshot_record(struct ltt_session *session,
                struct ltt_ust_session *usess = session->ust_session;
 
                if (use_tmp_output) {
+                       int64_t nb_packets_per_stream;
+
+                       nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+                                       tmp_output.max_size);
+                       if (nb_packets_per_stream < 0) {
+                               ret = LTTNG_ERR_MAX_SIZE_INVALID;
+                               goto error;
+                       }
                        ret = record_ust_snapshot(usess, &tmp_output, session,
-                                       wait, max_stream_size);
+                                       wait, nb_packets_per_stream);
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
@@ -3251,6 +3366,8 @@ int cmd_snapshot_record(struct ltt_session *session,
                        rcu_read_lock();
                        cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
                                        &iter.iter, sout, node.node) {
+                               int64_t nb_packets_per_stream;
+
                                /*
                                 * Make a local copy of the output and assign the possible
                                 * temporary value given by the caller.
@@ -3258,15 +3375,15 @@ int cmd_snapshot_record(struct ltt_session *session,
                                memset(&tmp_output, 0, sizeof(tmp_output));
                                memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-                               /* Use temporary max size. */
                                if (output->max_size != (uint64_t) -1ULL) {
                                        tmp_output.max_size = output->max_size;
                                }
 
-                               if (tmp_output.max_size != 0 &&
-                                               tmp_output.max_size < session_max_size) {
-                                       rcu_read_unlock();
+                               nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+                                               tmp_output.max_size);
+                               if (nb_packets_per_stream < 0) {
                                        ret = LTTNG_ERR_MAX_SIZE_INVALID;
+                                       rcu_read_unlock();
                                        goto error;
                                }
 
@@ -3279,7 +3396,7 @@ int cmd_snapshot_record(struct ltt_session *session,
                                tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
 
                                ret = record_ust_snapshot(usess, &tmp_output, session,
-                                               wait, max_stream_size);
+                                               wait, nb_packets_per_stream);
                                if (ret != LTTNG_OK) {
                                        rcu_read_unlock();
                                        goto error;
@@ -3300,6 +3417,29 @@ error:
        return ret;
 }
 
+/*
+ * Command LTTNG_SET_SESSION_SHM_PATH processed by the client thread.
+ */
+int cmd_set_session_shm_path(struct ltt_session *session,
+               const char *shm_path)
+{
+       /* Safety net */
+       assert(session);
+
+       /*
+        * Can only set shm path before session is started.
+        */
+       if (session->has_been_started) {
+               return LTTNG_ERR_SESSION_STARTED;
+       }
+
+       strncpy(session->shm_path, shm_path,
+               sizeof(session->shm_path));
+       session->shm_path[sizeof(session->shm_path) - 1] = '\0';
+
+       return 0;
+}
+
 /*
  * Init command subsystem.
  */
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