Fix: provide more precise error report for enable event

[lttng-modules.git] / lttng-events.c

diff --git a/lttng-events.c b/lttng-events.c
index b7e44221958d1230be181178dc3e90f5ce1990fa..97d82a297b911d9ad945cc6b88e484d87d2d8fb3 100644 (file)
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -27,10 +27,12 @@
 #include <linux/slab.h>
 #include <linux/jiffies.h>
 #include <linux/utsname.h>
+#include <linux/err.h>
 #include "wrapper/uuid.h"
 #include "wrapper/vmalloc.h"   /* for wrapper_vmalloc_sync_all() */
 #include "wrapper/random.h"
 #include "wrapper/tracepoint.h"
+#include "lttng-kernel-version.h"
 #include "lttng-events.h"
 #include "lttng-tracer.h"
 #include "lttng-abi-old.h"
@@ -60,9 +62,15 @@ void _lttng_metadata_channel_hangup(struct lttng_metadata_stream *stream);
 void synchronize_trace(void)
 {
        synchronize_sched();
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,4,0))
+#ifdef CONFIG_PREEMPT_RT_FULL
+       synchronize_rcu();
+#endif
+#else /* (LINUX_VERSION_CODE >= KERNEL_VERSION(3,4,0)) */
 #ifdef CONFIG_PREEMPT_RT
        synchronize_rcu();
 #endif
+#endif /* (LINUX_VERSION_CODE >= KERNEL_VERSION(3,4,0)) */
 }
 
 struct lttng_session *lttng_session_create(void)
@@ -359,18 +367,25 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
        int ret;
 
        mutex_lock(&sessions_mutex);
-       if (chan->free_event_id == -1U)
+       if (chan->free_event_id == -1U) {
+               event = ERR_PTR(-EMFILE);
                goto full;
+       }
        /*
         * This is O(n^2) (for each event, the loop is called at event
         * creation). Might require a hash if we have lots of events.
         */
-       list_for_each_entry(event, &chan->session->events, list)
-               if (!strcmp(event->desc->name, event_param->name))
+       list_for_each_entry(event, &chan->session->events, list) {
+               if (!strcmp(event->desc->name, event_param->name)) {
+                       event = ERR_PTR(-EEXIST);
                        goto exist;
+               }
+       }
        event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
-       if (!event)
+       if (!event) {
+               event = ERR_PTR(-ENOMEM);
                goto cache_error;
+       }
        event->chan = chan;
        event->filter = filter;
        event->id = chan->free_event_id++;
@@ -381,13 +396,17 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
        switch (event_param->instrumentation) {
        case LTTNG_KERNEL_TRACEPOINT:
                event->desc = lttng_event_get(event_param->name);
-               if (!event->desc)
+               if (!event->desc) {
+                       event = ERR_PTR(-ENOENT);
                        goto register_error;
+               }
                ret = kabi_2635_tracepoint_probe_register(event_param->name,
                                event->desc->probe_callback,
                                event);
-               if (ret)
+               if (ret) {
+                       event = ERR_PTR(-EINVAL);
                        goto register_error;
+               }
                break;
        case LTTNG_KERNEL_KPROBE:
                ret = lttng_kprobes_register(event_param->name,
@@ -395,8 +414,10 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
                                event_param->u.kprobe.offset,
                                event_param->u.kprobe.addr,
                                event);
-               if (ret)
+               if (ret) {
+                       event = ERR_PTR(-EINVAL);
                        goto register_error;
+               }
                ret = try_module_get(event->desc->owner);
                WARN_ON_ONCE(!ret);
                break;
@@ -407,8 +428,10 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
                /* kretprobe defines 2 events */
                event_return =
                        kmem_cache_zalloc(event_cache, GFP_KERNEL);
-               if (!event_return)
+               if (!event_return) {
+                       event = ERR_PTR(-ENOMEM);
                        goto register_error;
+               }
                event_return->chan = chan;
                event_return->filter = filter;
                event_return->id = chan->free_event_id++;
@@ -425,6 +448,7 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
                                event, event_return);
                if (ret) {
                        kmem_cache_free(event_cache, event_return);
+                       event = ERR_PTR(-EINVAL);
                        goto register_error;
                }
                /* Take 2 refs on the module: one per event. */
@@ -434,10 +458,12 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
                WARN_ON_ONCE(!ret);
                ret = _lttng_event_metadata_statedump(chan->session, chan,
                                                    event_return);
+               WARN_ON_ONCE(ret > 0);
                if (ret) {
                        kmem_cache_free(event_cache, event_return);
                        module_put(event->desc->owner);
                        module_put(event->desc->owner);
+                       event = ERR_PTR(ret);
                        goto statedump_error;
                }
                list_add(&event_return->list, &chan->session->events);
@@ -447,22 +473,31 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
                ret = lttng_ftrace_register(event_param->name,
                                event_param->u.ftrace.symbol_name,
                                event);
-               if (ret)
+               if (ret) {
+                       event = ERR_PTR(ret);
                        goto register_error;
+               }
                ret = try_module_get(event->desc->owner);
                WARN_ON_ONCE(!ret);
                break;
        case LTTNG_KERNEL_NOOP:
                event->desc = internal_desc;
-               if (!event->desc)
+               if (!event->desc) {
+                       event = ERR_PTR(-EINVAL);
                        goto register_error;
+               }
                break;
        default:
                WARN_ON_ONCE(1);
+               event = ERR_PTR(-EINVAL);
+               goto register_error;
        }
        ret = _lttng_event_metadata_statedump(chan->session, chan, event);
-       if (ret)
+       WARN_ON_ONCE(ret > 0);
+       if (ret) {
+               event = ERR_PTR(ret);
                goto statedump_error;
+       }
        list_add(&event->list, &chan->session->events);
        mutex_unlock(&sessions_mutex);
        return event;
@@ -475,7 +510,7 @@ cache_error:
 exist:
 full:
        mutex_unlock(&sessions_mutex);
-       return NULL;
+       return event;
 }
 
 /*
@@ -827,7 +862,7 @@ int _lttng_event_metadata_statedump(struct lttng_session *session,
 
        ret = lttng_metadata_printf(session,
                "event {\n"
-               "       name = %s;\n"
+               "       name = \"%s\";\n"
                "       id = %u;\n"
                "       stream_id = %u;\n",
                event->desc->name,
@@ -1252,3 +1287,6 @@ module_exit(lttng_events_exit);
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 MODULE_DESCRIPTION("LTTng Events");
+MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
+       __stringify(LTTNG_MODULES_MINOR_VERSION) "."
+       __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION));