2 * lttng-context-vppid.c
6 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; only
11 * version 2.1 of the License.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/sched.h>
26 #include <linux/syscalls.h>
27 #include "lttng-events.h"
28 #include "wrapper/ringbuffer/frontend_types.h"
29 #include "wrapper/vmalloc.h"
30 #include "lttng-tracer.h"
33 size_t vppid_get_size(size_t offset)
37 size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
38 size += sizeof(pid_t);
43 void vppid_record(struct lttng_ctx_field *field,
44 struct lib_ring_buffer_ctx *ctx,
45 struct lttng_channel *chan)
47 struct task_struct *parent;
51 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
52 * the current thread nsproxy to perform the lookup.
56 * TODO: when we eventually add RCU subsystem instrumentation,
57 * taking the rcu read lock here will trigger RCU tracing
58 * recursively. We should modify the kernel synchronization so
59 * it synchronizes both for RCU and RCU sched, and rely on
60 * rcu_read_lock_sched_notrace.
64 parent = rcu_dereference(current->real_parent);
65 if (!current->nsproxy)
68 vppid = task_tgid_vnr(parent);
70 lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid));
71 chan->ops->event_write(ctx, &vppid, sizeof(vppid));
74 int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
76 struct lttng_ctx_field *field;
78 field = lttng_append_context(ctx);
81 if (lttng_find_context(*ctx, "vppid")) {
82 lttng_remove_context_field(ctx, field);
85 field->event_field.name = "vppid";
86 field->event_field.type.atype = atype_integer;
87 field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
88 field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
89 field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t);
90 field->event_field.type.u.basic.integer.reverse_byte_order = 0;
91 field->event_field.type.u.basic.integer.base = 10;
92 field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
93 field->get_size = vppid_get_size;
94 field->record = vppid_record;
95 wrapper_vmalloc_sync_all();
98 EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);
100 MODULE_LICENSE("GPL and additional rights");
101 MODULE_AUTHOR("Mathieu Desnoyers");
102 MODULE_DESCRIPTION("Linux Trace Toolkit vPPID Context");