lib ring buffer must take private pointer copy before decrementing refcount
[lttng-modules.git] / lttng-context-vpid.c
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1/*
2 * (C) Copyright 2009-2011 -
3 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * LTTng vPID context.
6 *
7 * Dual LGPL v2.1/GPL v2 license.
8 */
9
10#include <linux/module.h>
11#include <linux/slab.h>
12#include <linux/sched.h>
13#include "ltt-events.h"
14#include "wrapper/ringbuffer/frontend_types.h"
15#include "wrapper/vmalloc.h"
16#include "ltt-tracer.h"
17
18static
19size_t vpid_get_size(size_t offset)
20{
21 size_t size = 0;
22
23 size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
24 size += sizeof(pid_t);
25 return size;
26}
27
28static
29void vpid_record(struct lttng_ctx_field *field,
30 struct lib_ring_buffer_ctx *ctx,
31 struct ltt_channel *chan)
32{
33 pid_t vpid;
34
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35 /*
36 * nsproxy can be NULL when scheduled out of exit.
37 */
38 if (!current->nsproxy)
39 vpid = 0;
40 else
41 vpid = task_tgid_vnr(current);
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42 lib_ring_buffer_align_ctx(ctx, ltt_alignof(vpid));
43 chan->ops->event_write(ctx, &vpid, sizeof(vpid));
44}
45
46int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx)
47{
48 struct lttng_ctx_field *field;
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49
50 field = lttng_append_context(ctx);
51 if (!field)
09fec6b4 52 return -ENOMEM;
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53 if (lttng_find_context(*ctx, "vpid")) {
54 lttng_remove_context_field(ctx, field);
55 return -EEXIST;
56 }
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57 field->event_field.name = "vpid";
58 field->event_field.type.atype = atype_integer;
59 field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
60 field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
61 field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
62 field->event_field.type.u.basic.integer.reverse_byte_order = 0;
63 field->event_field.type.u.basic.integer.base = 10;
64 field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
65 field->get_size = vpid_get_size;
66 field->record = vpid_record;
67 wrapper_vmalloc_sync_all();
68 return 0;
69}
70EXPORT_SYMBOL_GPL(lttng_add_vpid_to_ctx);
71
72MODULE_LICENSE("GPL and additional rights");
73MODULE_AUTHOR("Mathieu Desnoyers");
74MODULE_DESCRIPTION("Linux Trace Toolkit vPID Context");
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