Fix out of order channel insert in hash table

[lttng-tools.git] / lttng-sessiond / channel.c

diff --git a/lttng-sessiond/channel.c b/lttng-sessiond/channel.c
index 06b799db1d2132aab97e10ca2ad7e8970be1c10c..3dc04ccb83829ad2077dc2ced938d3ee6c40671b 100644 (file)
--- a/lttng-sessiond/channel.c
+++ b/lttng-sessiond/channel.c
@@ -20,11 +20,11 @@
 #include <unistd.h>
 
 #include <lttng/lttng.h>
+#include <lttng-ht.h>
 #include <lttng-sessiond-comm.h>
 #include <lttngerr.h>
 
 #include "channel.h"
-#include "hashtable.h"
 #include "kernel.h"
 #include "ust-ctl.h"
 #include "utils.h"
@@ -216,7 +216,7 @@ int channel_ust_create(struct ltt_ust_session *usess, int domain,
                struct lttng_channel *attr)
 {
        int ret = LTTCOMM_OK;
-       struct cds_lfht *chan_ht;
+       struct lttng_ht *chan_ht;
        struct ltt_ust_channel *uchan = NULL;
        struct lttng_channel *defattr = NULL;
 
@@ -236,11 +236,16 @@ int channel_ust_create(struct ltt_ust_session *usess, int domain,
                ret = LTTCOMM_FATAL;
                goto error;
        }
+       uchan->enabled = 1;
 
        switch (domain) {
        case LTTNG_DOMAIN_UST:
                DBG2("Channel %s being created in UST global domain", uchan->name);
-               chan_ht = usess->domain_global.channels;
+
+               /* Adding the channel to the channel hash table. */
+               rcu_read_lock();
+               lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
+               rcu_read_unlock();
 
                /* Enable channel for global domain */
                ret = ust_app_create_channel_glb(usess, uchan);
@@ -258,14 +263,16 @@ int channel_ust_create(struct ltt_ust_session *usess, int domain,
                goto error_free_chan;
        }
 
-       uchan->enabled = 1;
-       hashtable_add_unique(chan_ht, &uchan->node);
        DBG2("Channel %s created successfully", uchan->name);
 
        free(defattr);
        return LTTCOMM_OK;
 
 error_free_chan:
+       /*
+        * No need to remove the channel from the hash table because at this point
+        * it was not added hence the direct call and no call_rcu().
+        */
        trace_ust_destroy_channel(uchan);
 error:
        free(defattr);