Drop support for kernels < 3.0 from skb instrumentation

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

diff --git a/lttng-context-ppid.c b/lttng-context-ppid.c
index 342aa343337b2a55a380da763651a9e22225cf96..ef84ad1109e52967c94d7e272db510765c92492c 100644 (file)
--- a/lttng-context-ppid.c
+++ b/lttng-context-ppid.c
@@ -1,27 +1,27 @@
-/*
- * (C) Copyright       2009-2011 -
- *             Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * lttng-context-ppid.c
  *
  * LTTng PPID context.
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/syscalls.h>
-#include "ltt-events.h"
-#include "wrapper/ringbuffer/frontend_types.h"
-#include "wrapper/vmalloc.h"
-#include "ltt-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)
 {
        size_t size = 0;
 
-       size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+       size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
        size += sizeof(pid_t);
        return size;
 }
@@ -29,40 +29,68 @@ size_t ppid_get_size(size_t offset)
 static
 void ppid_record(struct lttng_ctx_field *field,
                 struct lib_ring_buffer_ctx *ctx,
-                struct ltt_channel *chan)
+                struct lttng_channel *chan)
 {
        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();
-       lib_ring_buffer_align_ctx(ctx, ltt_alignof(ppid));
+       lib_ring_buffer_align_ctx(ctx, lttng_alignof(ppid));
        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;
-       int ret;
 
        field = lttng_append_context(ctx);
        if (!field)
-               return ret;
+               return -ENOMEM;
+       if (lttng_find_context(*ctx, "ppid")) {
+               lttng_remove_context_field(ctx, field);
+               return -EEXIST;
+       }
        field->event_field.name = "ppid";
        field->event_field.type.atype = atype_integer;
        field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
-       field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
-       field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+       field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
+       field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t);
        field->event_field.type.u.basic.integer.reverse_byte_order = 0;
        field->event_field.type.u.basic.integer.base = 10;
        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");