Allow channel mode override in snapshot sessions

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

diff --git a/src/bin/lttng-sessiond/channel.c b/src/bin/lttng-sessiond/channel.c
index 7c95a0d2194d4e6de2e43e726b98ee05fcb2d2cd..88480c4b4e7b78fd63a2edc744618eadba0c36bc 100644 (file)
--- a/src/bin/lttng-sessiond/channel.c
+++ b/src/bin/lttng-sessiond/channel.c
@@ -31,6 +31,7 @@
 #include "ust-ctl.h"
 #include "utils.h"
 #include "ust-app.h"
+#include "agent.h"
 
 /*
  * Return allocated channel attributes.
@@ -178,6 +179,19 @@ error:
        return ret;
 }
 
+static int channel_validate(struct lttng_channel *attr)
+{
+       /*
+        * The ringbuffer (both in user space and kernel) behaves badly
+        * in overwrite mode and with less than 2 subbuffers so block it
+        * right away and send back an invalid attribute error.
+        */
+       if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
+               return -1;
+       }
+       return 0;
+}
+
 /*
  * Create kernel channel of the kernel session and notify kernel thread.
  */
@@ -200,12 +214,25 @@ int channel_kernel_create(struct ltt_kernel_session *ksession,
                attr = defattr;
        }
 
+       /*
+        * Set the overwrite mode for this channel based on the session
+        * type unless the client explicitly overrides the channel mode.
+        */
+       if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
+               attr->attr.overwrite = !!ksession->snapshot_mode;
+       }
+
+       /* Enforce mmap output for snapshot sessions. */
        if (ksession->snapshot_mode) {
-               /* Force channel attribute for snapshot mode. */
-               attr->attr.overwrite = 1;
                attr->attr.output = LTTNG_EVENT_MMAP;
        }
 
+       /* Validate common channel properties. */
+       if (channel_validate(attr) < 0) {
+               ret = LTTNG_ERR_INVALID;
+               goto error;
+       }
+
        /* Channel not found, creating it */
        ret = kernel_create_channel(ksession, attr);
        if (ret < 0) {
@@ -272,6 +299,7 @@ int channel_ust_create(struct ltt_ust_session *usess,
        int ret = LTTNG_OK;
        struct ltt_ust_channel *uchan = NULL;
        struct lttng_channel *defattr = NULL;
+       enum lttng_domain_type domain = LTTNG_DOMAIN_UST;
 
        assert(usess);
 
@@ -283,14 +311,39 @@ int channel_ust_create(struct ltt_ust_session *usess,
                        goto error;
                }
                attr = defattr;
+       } else {
+               /*
+                * HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
+                * based on the default name.
+                */
+               if (!strcmp(attr->name, DEFAULT_JUL_CHANNEL_NAME)) {
+                       domain = LTTNG_DOMAIN_JUL;
+               } else if (!strcmp(attr->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
+                       domain = LTTNG_DOMAIN_LOG4J;
+               } else if (!strcmp(attr->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
+                       domain = LTTNG_DOMAIN_PYTHON;
+               }
+       }
+
+       /*
+        * Set the overwrite mode for this channel based on the session
+        * type unless the client explicitly overrides the channel mode.
+        */
+       if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
+               attr->attr.overwrite = !!usess->snapshot_mode;
        }
 
+       /* Enforce mmap output for snapshot sessions. */
        if (usess->snapshot_mode) {
-               /* Force channel attribute for snapshot mode. */
-               attr->attr.overwrite = 1;
                attr->attr.output = LTTNG_EVENT_MMAP;
        }
 
+       /* Validate common channel properties. */
+       if (channel_validate(attr) < 0) {
+               ret = LTTNG_ERR_INVALID;
+               goto error;
+       }
+
        /*
         * Validate UST buffer size and number of buffers: must both be power of 2
         * and nonzero. We validate right here for UST, because applications will
@@ -343,24 +396,12 @@ int channel_ust_create(struct ltt_ust_session *usess,
        }
 
        /* Create UST channel */
-       uchan = trace_ust_create_channel(attr, LTTNG_DOMAIN_UST);
+       uchan = trace_ust_create_channel(attr, domain);
        if (uchan == NULL) {
                ret = LTTNG_ERR_FATAL;
                goto error;
        }
 
-       /*
-        * HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
-        * based on the default name.
-        */
-       if (!strcmp(uchan->name, DEFAULT_JUL_CHANNEL_NAME)) {
-               uchan->domain = LTTNG_DOMAIN_JUL;
-       } else if (!strcmp(uchan->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
-               uchan->domain = LTTNG_DOMAIN_LOG4J;
-       } else if (!strcmp(uchan->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
-               uchan->domain = LTTNG_DOMAIN_PYTHON;
-       }
-
        uchan->enabled = 1;
        if (trace_ust_is_max_id(usess->used_channel_id)) {
                ret = LTTNG_ERR_UST_CHAN_FAIL;
@@ -405,6 +446,18 @@ int channel_ust_create(struct ltt_ust_session *usess,
        rcu_read_unlock();
 
        DBG2("Channel %s created successfully", uchan->name);
+       if (domain != LTTNG_DOMAIN_UST) {
+               struct agent *agt = trace_ust_find_agent(usess, domain);
+
+               if (!agt) {
+                       agt = agent_create(domain);
+                       if (!agt) {
+                               ret = LTTNG_ERR_NOMEM;
+                               goto error_free_chan;
+                       }
+                       agent_add(agt, usess->agents);
+               }
+       }
 
        free(defattr);
        return LTTNG_OK;