Version 2.7.7

[lttng-modules.git] / lttng-context-vppid.c

diff --git a/lttng-context-vppid.c b/lttng-context-vppid.c
index f723a5c0cf78202dd2915a0217b10dcb647a4fdf..80b1f9e7a20222f3e232e1089023abb839fbee58 100644 (file)
--- a/lttng-context-vppid.c
+++ b/lttng-context-vppid.c
@@ -71,6 +71,36 @@ void vppid_record(struct lttng_ctx_field *field,
        chan->ops->event_write(ctx, &vppid, sizeof(vppid));
 }
 
+static
+void vppid_get_value(struct lttng_ctx_field *field,
+               union lttng_ctx_value *value)
+{
+       struct task_struct *parent;
+       pid_t vppid;
+
+       /*
+        * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
+        * the current thread nsproxy to perform the lookup.
+        */
+
+       /*
+        * TODO: when we eventually add RCU subsystem instrumentation,
+        * taking the rcu read lock here will trigger RCU tracing
+        * recursively. We should modify the kernel synchronization so
+        * it synchronizes both for RCU and RCU sched, and rely on
+        * rcu_read_lock_sched_notrace.
+        */
+
+       rcu_read_lock();
+       parent = rcu_dereference(current->real_parent);
+       if (!current->nsproxy)
+               vppid = 0;
+       else
+               vppid = task_tgid_vnr(parent);
+       rcu_read_unlock();
+       value->s64 = vppid;
+}
+
 int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
 {
        struct lttng_ctx_field *field;
@@ -92,15 +122,9 @@ int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
        field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
        field->get_size = vppid_get_size;
        field->record = vppid_record;
+       field->get_value = vppid_get_value;
+       lttng_context_update(*ctx);
        wrapper_vmalloc_sync_all();
        return 0;
 }
 EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);
-
-MODULE_LICENSE("GPL and additional rights");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Linux Trace Toolkit vPPID Context");
-MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
-       __stringify(LTTNG_MODULES_MINOR_VERSION) "."
-       __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
-       LTTNG_MODULES_EXTRAVERSION);