Fix: update writeback instrumentation for kernel 4.14

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

diff --git a/lttng-context-ppid.c b/lttng-context-ppid.c
index 878c6886ccf45c8858dd7eb1b40094a4c029a847..8b7c8ed7604c02166f3cd200506a40811a9e5f3a 100644 (file)
--- a/lttng-context-ppid.c
+++ b/lttng-context-ppid.c
@@ -24,10 +24,10 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/syscalls.h>
-#include "lttng-events.h"
-#include "wrapper/ringbuffer/frontend_types.h"
-#include "wrapper/vmalloc.h"
-#include "lttng-tracer.h"
+#include <lttng-events.h>
+#include <wrapper/ringbuffer/frontend_types.h>
+#include <wrapper/vmalloc.h>
+#include <lttng-tracer.h>
 
 static
 size_t ppid_get_size(size_t offset)
@@ -46,7 +46,6 @@ void ppid_record(struct lttng_ctx_field *field,
 {
        pid_t ppid;
 
-
        /*
         * TODO: when we eventually add RCU subsystem instrumentation,
         * taking the rcu read lock here will trigger RCU tracing
@@ -54,7 +53,6 @@ void ppid_record(struct lttng_ctx_field *field,
         * it synchronizes both for RCU and RCU sched, and rely on
         * rcu_read_lock_sched_notrace.
         */
-
        rcu_read_lock();
        ppid = task_tgid_nr(current->real_parent);
        rcu_read_unlock();
@@ -62,6 +60,26 @@ void ppid_record(struct lttng_ctx_field *field,
        chan->ops->event_write(ctx, &ppid, sizeof(ppid));
 }
 
+static
+void ppid_get_value(struct lttng_ctx_field *field,
+               struct lttng_probe_ctx *lttng_probe_ctx,
+               union lttng_ctx_value *value)
+{
+       pid_t ppid;
+
+       /*
+        * 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();
+       ppid = task_tgid_nr(current->real_parent);
+       rcu_read_unlock();
+       value->s64 = ppid;
+}
+
 int lttng_add_ppid_to_ctx(struct lttng_ctx **ctx)
 {
        struct lttng_ctx_field *field;
@@ -83,11 +101,9 @@ int lttng_add_ppid_to_ctx(struct lttng_ctx **ctx)
        field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
        field->get_size = ppid_get_size;
        field->record = ppid_record;
+       field->get_value = ppid_get_value;
+       lttng_context_update(*ctx);
        wrapper_vmalloc_sync_all();
        return 0;
 }
 EXPORT_SYMBOL_GPL(lttng_add_ppid_to_ctx);
-
-MODULE_LICENSE("GPL and additional rights");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Linux Trace Toolkit PPID Context");