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 e3a7324b84ab82ebb31761500d812c0c1c728f80..97d82a297b911d9ad945cc6b88e484d87d2d8fb3 100644 (file)
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -27,6 +27,7 @@
 #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"
@@ -366,18 +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++;
@@ -388,13 +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,
@@ -402,8 +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;
@@ -414,8 +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++;
@@ -432,6 +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. */
@@ -441,10 +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);
@@ -454,23 +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;
@@ -483,7 +510,7 @@ cache_error:
 exist:
 full:
        mutex_unlock(&sessions_mutex);
-       return NULL;
+       return event;
 }
 
 /*