Fix metadata buffer wait/wakeup

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

diff --git a/ltt-events.c b/ltt-events.c
index a94e8f9a1dde6a6e315133e59c66e3659455f99d..28f7bdb44ec687e720920acc8c07e38b37dae4b6 100644 (file)
--- a/ltt-events.c
+++ b/ltt-events.c
@@ -14,7 +14,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/jiffies.h>
-#include <linux/uuid.h>
+#include "wrapper/uuid.h"
 #include "wrapper/vmalloc.h"   /* for wrapper_vmalloc_sync_all() */
 #include "ltt-events.h"
 #include "ltt-tracer.h"
@@ -34,8 +34,6 @@ int _ltt_event_metadata_statedump(struct ltt_session *session,
 static
 int _ltt_session_metadata_statedump(struct ltt_session *session);
 
-
-static
 void synchronize_trace(void)
 {
        synchronize_sched();
@@ -108,12 +106,9 @@ int ltt_session_enable(struct ltt_session *session)
 
        ACCESS_ONCE(session->active) = 1;
        ACCESS_ONCE(session->been_active) = 1;
-       synchronize_trace();    /* Wait for in-flight events to complete */
        ret = _ltt_session_metadata_statedump(session);
-       if (ret) {
+       if (ret)
                ACCESS_ONCE(session->active) = 0;
-               synchronize_trace();    /* Wait for in-flight events to complete */
-       }
 end:
        mutex_unlock(&sessions_mutex);
        return ret;
@@ -129,7 +124,6 @@ int ltt_session_disable(struct ltt_session *session)
                goto end;
        }
        ACCESS_ONCE(session->active) = 0;
-       synchronize_trace();    /* Wait for in-flight events to complete */
 end:
        mutex_unlock(&sessions_mutex);
        return ret;
@@ -139,6 +133,8 @@ int ltt_channel_enable(struct ltt_channel *channel)
 {
        int old;
 
+       if (channel == channel->session->metadata)
+               return -EPERM;
        old = xchg(&channel->enabled, 1);
        if (old)
                return -EEXIST;
@@ -149,6 +145,8 @@ int ltt_channel_disable(struct ltt_channel *channel)
 {
        int old;
 
+       if (channel == channel->session->metadata)
+               return -EPERM;
        old = xchg(&channel->enabled, 0);
        if (!old)
                return -EEXIST;
@@ -159,6 +157,8 @@ int ltt_event_enable(struct ltt_event *event)
 {
        int old;
 
+       if (event->chan == event->chan->session->metadata)
+               return -EPERM;
        old = xchg(&event->enabled, 1);
        if (old)
                return -EEXIST;
@@ -169,6 +169,8 @@ int ltt_event_disable(struct ltt_event *event)
 {
        int old;
 
+       if (event->chan == event->chan->session->metadata)
+               return -EPERM;
        old = xchg(&event->enabled, 0);
        if (!old)
                return -EEXIST;
@@ -194,7 +196,7 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                                       unsigned int read_timer_interval)
 {
        struct ltt_channel *chan;
-       struct ltt_transport *transport;
+       struct ltt_transport *transport = NULL;
 
        mutex_lock(&sessions_mutex);
        if (session->been_active)
@@ -205,6 +207,10 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                       transport_name);
                goto notransport;
        }
+       if (!try_module_get(transport->owner)) {
+               printk(KERN_WARNING "LTT : Can't lock transport module.\n");
+               goto notransport;
+       }
        chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
        if (!chan)
                goto nomem;
@@ -222,6 +228,7 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
                goto create_error;
        chan->enabled = 1;
        chan->ops = &transport->ops;
+       chan->transport = transport;
        list_add(&chan->list, &session->chan);
        mutex_unlock(&sessions_mutex);
        return chan;
@@ -229,6 +236,8 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 create_error:
        kfree(chan);
 nomem:
+       if (transport)
+               module_put(transport->owner);
 notransport:
 active:
        mutex_unlock(&sessions_mutex);
@@ -242,6 +251,7 @@ static
 void _ltt_channel_destroy(struct ltt_channel *chan)
 {
        chan->ops->channel_destroy(chan->chan);
+       module_put(chan->transport->owner);
        list_del(&chan->list);
        lttng_destroy_context(chan->ctx);
        kfree(chan);
@@ -299,6 +309,49 @@ struct ltt_event *ltt_event_create(struct ltt_channel *chan,
                ret = try_module_get(event->desc->owner);
                WARN_ON_ONCE(!ret);
                break;
+       case LTTNG_KERNEL_KRETPROBE:
+       {
+               struct ltt_event *event_return;
+
+               /* kretprobe defines 2 events */
+               event_return =
+                       kmem_cache_zalloc(event_cache, GFP_KERNEL);
+               if (!event_return)
+                       goto register_error;
+               event_return->chan = chan;
+               event_return->filter = filter;
+               event_return->id = chan->free_event_id++;
+               event_return->enabled = 1;
+               event_return->instrumentation = event_param->instrumentation;
+               /*
+                * Populate ltt_event structure before kretprobe registration.
+                */
+               smp_wmb();
+               ret = lttng_kretprobes_register(event_param->name,
+                               event_param->u.kretprobe.symbol_name,
+                               event_param->u.kretprobe.offset,
+                               event_param->u.kretprobe.addr,
+                               event, event_return);
+               if (ret) {
+                       kmem_cache_free(event_cache, event_return);
+                       goto register_error;
+               }
+               /* Take 2 refs on the module: one per event. */
+               ret = try_module_get(event->desc->owner);
+               WARN_ON_ONCE(!ret);
+               ret = try_module_get(event->desc->owner);
+               WARN_ON_ONCE(!ret);
+               ret = _ltt_event_metadata_statedump(chan->session, chan,
+                                                   event_return);
+               if (ret) {
+                       kmem_cache_free(event_cache, event_return);
+                       module_put(event->desc->owner);
+                       module_put(event->desc->owner);
+                       goto statedump_error;
+               }
+               list_add(&event_return->list, &chan->session->events);
+               break;
+       }
        case LTTNG_KERNEL_FUNCTION:
                ret = lttng_ftrace_register(event_param->name,
                                event_param->u.ftrace.symbol_name,
@@ -351,6 +404,10 @@ int _ltt_event_unregister(struct ltt_event *event)
                lttng_kprobes_unregister(event);
                ret = 0;
                break;
+       case LTTNG_KERNEL_KRETPROBE:
+               lttng_kretprobes_unregister(event);
+               ret = 0;
+               break;
        case LTTNG_KERNEL_FUNCTION:
                lttng_ftrace_unregister(event);
                ret = 0;
@@ -375,6 +432,10 @@ void _ltt_event_destroy(struct ltt_event *event)
                module_put(event->desc->owner);
                lttng_kprobes_destroy_private(event);
                break;
+       case LTTNG_KERNEL_KRETPROBE:
+               module_put(event->desc->owner);
+               lttng_kretprobes_destroy_private(event);
+               break;
        case LTTNG_KERNEL_FUNCTION:
                module_put(event->desc->owner);
                lttng_ftrace_destroy_private(event);
@@ -426,7 +487,7 @@ int lttng_metadata_printf(struct ltt_session *session,
                 * we need to bail out after timeout or being
                 * interrupted.
                 */
-               waitret = wait_event_interruptible_timeout(*chan->ops->get_reader_wait_queue(chan->chan),
+               waitret = wait_event_interruptible_timeout(*chan->ops->get_writer_buf_wait_queue(chan->chan, -1),
                        ({
                                ret = chan->ops->event_reserve(&ctx, 0);
                                ret != -ENOBUFS || !ret;