Fix RCU-related hangs: incorrect lttng_ht_destroy use
[lttng-tools.git] / src / bin / lttng-sessiond / trace-ust.c
index 81cb4db63180216b76d42ab3f628788525c06d89..7592d774177a43abb8782424084c711e371bcc5c 100644 (file)
@@ -24,6 +24,7 @@
 #include <common/common.h>
 #include <common/defaults.h>
 
+#include "buffer-registry.h"
 #include "trace-ust.h"
 
 /*
@@ -116,7 +117,8 @@ no_match:
 }
 
 /*
- * Find the channel in the hashtable.
+ * Find the channel in the hashtable and return channel pointer. RCU read side
+ * lock MUST be acquired before calling this.
  */
 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
                char *name)
@@ -124,14 +126,11 @@ struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
        struct lttng_ht_node_str *node;
        struct lttng_ht_iter iter;
 
-       rcu_read_lock();
        lttng_ht_lookup(ht, (void *)name, &iter);
        node = lttng_ht_iter_get_node_str(&iter);
        if (node == NULL) {
-               rcu_read_unlock();
                goto error;
        }
-       rcu_read_unlock();
 
        DBG2("Trace UST channel %s found by name", name);
 
@@ -143,7 +142,8 @@ error:
 }
 
 /*
- * Find the event in the hashtable.
+ * Find the event in the hashtable and return event pointer. RCU read side lock
+ * MUST be acquired before calling this.
  */
 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
                char *name, struct lttng_filter_bytecode *filter, int loglevel)
@@ -180,8 +180,7 @@ error:
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_ust_session *trace_ust_create_session(char *path,
-               unsigned int session_id)
+struct ltt_ust_session *trace_ust_create_session(unsigned int session_id)
 {
        struct ltt_ust_session *lus;
 
@@ -196,9 +195,17 @@ struct ltt_ust_session *trace_ust_create_session(char *path,
        lus->id = session_id;
        lus->start_trace = 0;
 
-       /* Alloc UST domain hash tables */
-       lus->domain_pid = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
-       lus->domain_exec = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+       /*
+        * Default buffer type. This can be changed through an enable channel
+        * requesting a different type. Note that this can only be changed once
+        * during the session lifetime which is at the first enable channel and
+        * only before start. The flag buffer_type_changed indicates the status.
+        */
+       lus->buffer_type = LTTNG_BUFFER_PER_PID;
+       /* Once set to 1, the buffer_type is immutable for the session. */
+       lus->buffer_type_changed = 0;
+       /* Init it in case it get used after allocation. */
+       CDS_INIT_LIST_HEAD(&lus->buffer_reg_uid_list);
 
        /* Alloc UST global domain channels' HT */
        lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
@@ -216,36 +223,12 @@ struct ltt_ust_session *trace_ust_create_session(char *path,
         */
        lus->tmp_consumer = NULL;
 
-       /* Use the default consumer output which is the tracing session path. */
-       if (path && strlen(path) > 0) {
-               int ret;
-
-               ret = snprintf(lus->consumer->dst.trace_path, PATH_MAX,
-                               "%s" DEFAULT_UST_TRACE_DIR, path);
-               if (ret < 0) {
-                       PERROR("snprintf UST consumer trace path");
-                       goto error_path;
-               }
-
-               /* Set session path */
-               ret = snprintf(lus->pathname, PATH_MAX, "%s" DEFAULT_UST_TRACE_DIR,
-                               path);
-               if (ret < 0) {
-                       PERROR("snprintf kernel traces path");
-                       goto error_path;
-               }
-       }
-
        DBG2("UST trace session create successful");
 
        return lus;
 
-error_path:
-       consumer_destroy_output(lus->consumer);
 error_consumer:
        lttng_ht_destroy(lus->domain_global.channels);
-       lttng_ht_destroy(lus->domain_exec);
-       lttng_ht_destroy(lus->domain_pid);
        free(lus);
 error:
        return NULL;
@@ -256,14 +239,11 @@ error:
  *
  * Return pointer to structure or NULL.
  */
-struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan,
-               char *path)
+struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan)
 {
-       int ret;
        struct ltt_ust_channel *luc;
 
        assert(chan);
-       assert(path);
 
        luc = zmalloc(sizeof(struct ltt_ust_channel));
        if (luc == NULL) {
@@ -296,23 +276,14 @@ struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan,
        luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
        luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 
-       /* Set trace output path */
-       ret = snprintf(luc->pathname, PATH_MAX, "%s", path);
-       if (ret < 0) {
-               PERROR("asprintf ust create channel");
-               goto error_free_channel;
-       }
+       /* On-disk circular buffer parameters */
+       luc->tracefile_size = chan->attr.tracefile_size;
+       luc->tracefile_count = chan->attr.tracefile_count;
 
        DBG2("Trace UST channel %s created", luc->name);
 
-       return luc;
-
-error_free_channel:
-       lttng_ht_destroy(luc->ctx);
-       lttng_ht_destroy(luc->events);
-       free(luc);
 error:
-       return NULL;
+       return luc;
 }
 
 /*
@@ -413,13 +384,13 @@ struct ltt_ust_metadata *trace_ust_create_metadata(char *path)
        lum->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
        lum->attr.subbuf_size = default_get_metadata_subbuf_size();
        lum->attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
-       lum->attr.switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
-       lum->attr.read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
+       lum->attr.switch_timer_interval = DEFAULT_UST_CHANNEL_SWITCH_TIMER;
+       lum->attr.read_timer_interval = DEFAULT_UST_CHANNEL_READ_TIMER;
        lum->attr.output = LTTNG_UST_MMAP;
 
        lum->handle = -1;
        /* Set metadata trace path */
-       ret = snprintf(lum->pathname, PATH_MAX, "%s/metadata", path);
+       ret = snprintf(lum->pathname, PATH_MAX, "%s/" DEFAULT_METADATA_NAME, path);
        if (ret < 0) {
                PERROR("asprintf ust metadata");
                goto error_free_metadata;
@@ -503,12 +474,14 @@ static void destroy_contexts(struct lttng_ht *ht)
 
        assert(ht);
 
+       rcu_read_lock();
        cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
                ret = lttng_ht_del(ht, &iter);
                if (!ret) {
                        call_rcu(&node->head, destroy_context_rcu);
                }
        }
+       rcu_read_unlock();
 
        lttng_ht_destroy(ht);
 }
@@ -549,34 +522,34 @@ static void destroy_events(struct lttng_ht *events)
 
        assert(events);
 
+       rcu_read_lock();
        cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
                ret = lttng_ht_del(events, &iter);
                assert(!ret);
                call_rcu(&node->head, destroy_event_rcu);
        }
+       rcu_read_unlock();
 
        lttng_ht_destroy(events);
 }
 
 /*
  * Cleanup ust channel structure.
+ *
+ * Should _NOT_ be called with RCU read lock held.
  */
-void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
+static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 {
        assert(channel);
 
        DBG2("Trace destroy UST channel %s", channel->name);
 
-       rcu_read_lock();
-
        /* Destroying all events of the channel */
        destroy_events(channel->events);
        /* Destroying all context of the channel */
        destroy_contexts(channel->ctx);
 
        free(channel);
-
-       rcu_read_unlock();
 }
 
 /*
@@ -589,7 +562,12 @@ static void destroy_channel_rcu(struct rcu_head *head)
        struct ltt_ust_channel *channel =
                caa_container_of(node, struct ltt_ust_channel, node);
 
-       trace_ust_destroy_channel(channel);
+       _trace_ust_destroy_channel(channel);
+}
+
+void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
+{
+       call_rcu(&channel->node.head, destroy_channel_rcu);
 }
 
 /*
@@ -624,50 +602,9 @@ static void destroy_channels(struct lttng_ht *channels)
                assert(!ret);
                call_rcu(&node->head, destroy_channel_rcu);
        }
-
-       lttng_ht_destroy(channels);
-
        rcu_read_unlock();
-}
 
-/*
- * Cleanup UST pid domain.
- */
-static void destroy_domain_pid(struct lttng_ht *ht)
-{
-       int ret;
-       struct lttng_ht_iter iter;
-       struct ltt_ust_domain_pid *dpid;
-
-       assert(ht);
-
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, dpid, node.node) {
-               ret = lttng_ht_del(ht , &iter);
-               assert(!ret);
-               destroy_channels(dpid->channels);
-       }
-
-       lttng_ht_destroy(ht);
-}
-
-/*
- * Cleanup UST exec name domain.
- */
-static void destroy_domain_exec(struct lttng_ht *ht)
-{
-       int ret;
-       struct lttng_ht_iter iter;
-       struct ltt_ust_domain_exec *dexec;
-
-       assert(ht);
-
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, dexec, node.node) {
-               ret = lttng_ht_del(ht , &iter);
-               assert(!ret);
-               destroy_channels(dexec->channels);
-       }
-
-       lttng_ht_destroy(ht);
+       lttng_ht_destroy(channels);
 }
 
 /*
@@ -682,24 +619,30 @@ static void destroy_domain_global(struct ltt_ust_domain_global *dom)
 
 /*
  * Cleanup ust session structure
+ *
+ * Should *NOT* be called with RCU read-side lock held.
  */
 void trace_ust_destroy_session(struct ltt_ust_session *session)
 {
-       assert(session);
+       struct buffer_reg_uid *reg, *sreg;
 
-       rcu_read_lock();
+       assert(session);
 
        DBG2("Trace UST destroy session %u", session->id);
 
        /* Cleaning up UST domain */
        destroy_domain_global(&session->domain_global);
-       destroy_domain_pid(session->domain_pid);
-       destroy_domain_exec(session->domain_exec);
+
+       /* Cleanup UID buffer registry object(s). */
+       cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
+                       lnode) {
+               cds_list_del(&reg->lnode);
+               buffer_reg_uid_remove(reg);
+               buffer_reg_uid_destroy(reg, session->consumer);
+       }
 
        consumer_destroy_output(session->consumer);
        consumer_destroy_output(session->tmp_consumer);
 
        free(session);
-
-       rcu_read_unlock();
 }
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