fix: vmalloc on v5.8 without KALLSYMS

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

diff --git a/lttng-events.c b/lttng-events.c
index a1c8445a20bbf9e86a22f408af109cb0421c04a4..cfe2a3529de33efb0184409d4dbdbd105eb93b8a 100644 (file)
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -27,10 +27,10 @@
 #include <linux/jhash.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
-#include <linux/uuid.h>
 #include <linux/dmi.h>
 
-#include <wrapper/vmalloc.h>   /* for wrapper_vmalloc_sync_all() */
+#include <wrapper/uuid.h>
+#include <wrapper/vmalloc.h>   /* for wrapper_vmalloc_sync_mappings() */
 #include <wrapper/random.h>
 #include <wrapper/tracepoint.h>
 #include <wrapper/list.h>
@@ -130,7 +130,7 @@ struct lttng_session *lttng_session_create(void)
                goto err;
        INIT_LIST_HEAD(&session->chan);
        INIT_LIST_HEAD(&session->events);
-       uuid_le_gen(&session->uuid);
+       lttng_guid_gen(&session->uuid);
 
        metadata_cache = kzalloc(sizeof(struct lttng_metadata_cache),
                        GFP_KERNEL);
@@ -1622,7 +1622,7 @@ void lttng_session_lazy_sync_enablers(struct lttng_session *session)
  * was written and a negative value on error.
  */
 int lttng_metadata_output_channel(struct lttng_metadata_stream *stream,
-               struct channel *chan)
+               struct channel *chan, bool *coherent)
 {
        struct lib_ring_buffer_ctx ctx;
        int ret = 0;
@@ -1661,6 +1661,7 @@ int lttng_metadata_output_channel(struct lttng_metadata_stream *stream,
        ret = stream->transport->ops.event_reserve(&ctx, 0);
        if (ret != 0) {
                printk(KERN_WARNING "LTTng: Metadata event reservation failed\n");
+               stream->coherent = false;
                goto end;
        }
        stream->transport->ops.event_write(&ctx,
@@ -1668,18 +1669,43 @@ int lttng_metadata_output_channel(struct lttng_metadata_stream *stream,
                        reserve_len);
        stream->transport->ops.event_commit(&ctx);
        stream->metadata_in += reserve_len;
+       if (reserve_len < len || stream->metadata_cache->producing != 0)
+               stream->coherent = false;
+       else
+               stream->coherent = true;
        ret = reserve_len;
 
 end:
+       if (coherent)
+               *coherent = stream->coherent;
        mutex_unlock(&stream->metadata_cache->lock);
        return ret;
 }
 
+static
+void lttng_metadata_begin(struct lttng_session *session)
+{
+       mutex_lock(&session->metadata_cache->lock);
+       session->metadata_cache->producing++;
+       mutex_unlock(&session->metadata_cache->lock);
+}
+
+static
+void lttng_metadata_end(struct lttng_session *session)
+{
+       mutex_lock(&session->metadata_cache->lock);
+       WARN_ON_ONCE(!session->metadata_cache->producing);
+       session->metadata_cache->producing--;
+       mutex_unlock(&session->metadata_cache->lock);
+}
+
 /*
  * Write the metadata to the metadata cache.
  * Must be called with sessions_mutex held.
  * The metadata cache lock protects us from concurrent read access from
  * thread outputting metadata content to ring buffer.
+ * The content of the printf is printed as a single atomic metadata
+ * transaction.
  */
 int lttng_metadata_printf(struct lttng_session *session,
                          const char *fmt, ...)
@@ -1699,6 +1725,7 @@ int lttng_metadata_printf(struct lttng_session *session,
 
        len = strlen(str);
        mutex_lock(&session->metadata_cache->lock);
+       session->metadata_cache->producing++;
        if (session->metadata_cache->metadata_written + len >
                        session->metadata_cache->cache_alloc) {
                char *tmp_cache_realloc;
@@ -1724,6 +1751,7 @@ int lttng_metadata_printf(struct lttng_session *session,
                        session->metadata_cache->metadata_written,
                        str, len);
        session->metadata_cache->metadata_written += len;
+       session->metadata_cache->producing--;
        mutex_unlock(&session->metadata_cache->lock);
        kfree(str);
 
@@ -1733,6 +1761,7 @@ int lttng_metadata_printf(struct lttng_session *session,
        return 0;
 
 err:
+       session->metadata_cache->producing--;
        mutex_unlock(&session->metadata_cache->lock);
        kfree(str);
        return -ENOMEM;
@@ -2270,6 +2299,8 @@ int _lttng_fields_metadata_statedump(struct lttng_session *session,
 
 /*
  * Must be called with sessions_mutex held.
+ * The entire event metadata is printed as a single atomic metadata
+ * transaction.
  */
 static
 int _lttng_event_metadata_statedump(struct lttng_session *session,
@@ -2283,6 +2314,8 @@ int _lttng_event_metadata_statedump(struct lttng_session *session,
        if (chan->channel_type == METADATA_CHANNEL)
                return 0;
 
+       lttng_metadata_begin(session);
+
        ret = lttng_metadata_printf(session,
                "event {\n"
                "       name = \"%s\";\n"
@@ -2332,12 +2365,15 @@ int _lttng_event_metadata_statedump(struct lttng_session *session,
 
        event->metadata_dumped = 1;
 end:
+       lttng_metadata_end(session);
        return ret;
 
 }
 
 /*
  * Must be called with sessions_mutex held.
+ * The entire channel metadata is printed as a single atomic metadata
+ * transaction.
  */
 static
 int _lttng_channel_metadata_statedump(struct lttng_session *session,
@@ -2351,6 +2387,8 @@ int _lttng_channel_metadata_statedump(struct lttng_session *session,
        if (chan->channel_type == METADATA_CHANNEL)
                return 0;
 
+       lttng_metadata_begin(session);
+
        WARN_ON_ONCE(!chan->header_type);
        ret = lttng_metadata_printf(session,
                "stream {\n"
@@ -2384,6 +2422,7 @@ int _lttng_channel_metadata_statedump(struct lttng_session *session,
 
        chan->metadata_dumped = 1;
 end:
+       lttng_metadata_end(session);
        return ret;
 }
 
@@ -2571,6 +2610,9 @@ int _lttng_session_metadata_statedump(struct lttng_session *session)
 
        if (!READ_ONCE(session->active))
                return 0;
+
+       lttng_metadata_begin(session);
+
        if (session->metadata_dumped)
                goto skip_session;
 
@@ -2743,6 +2785,7 @@ skip_session:
        }
        session->metadata_dumped = 1;
 end:
+       lttng_metadata_end(session);
        return ret;
 }
 
@@ -2753,9 +2796,9 @@ end:
  * Registers a transport which can be used as output to extract the data out of
  * LTTng. The module calling this registration function must ensure that no
  * trap-inducing code will be executed by the transport functions. E.g.
- * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
+ * vmalloc_sync_mappings() must be called between a vmalloc and the moment the memory
  * is made visible to the transport function. This registration acts as a
- * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
+ * vmalloc_sync_mappings. Therefore, only if the module allocates virtual memory
  * after its registration must it synchronize the TLBs.
  */
 void lttng_transport_register(struct lttng_transport *transport)
@@ -2763,9 +2806,9 @@ void lttng_transport_register(struct lttng_transport *transport)
        /*
         * Make sure no page fault can be triggered by the module about to be
         * registered. We deal with this here so we don't have to call
-        * vmalloc_sync_all() in each module's init.
+        * vmalloc_sync_mappings() in each module's init.
         */
-       wrapper_vmalloc_sync_all();
+       wrapper_vmalloc_sync_mappings();
 
        mutex_lock(&sessions_mutex);
        list_add_tail(&transport->node, &lttng_transport_list);