lib ring buffer must take private pointer copy before decrementing refcount
[lttng-modules.git] / lttng-context-nice.c
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1/*
2 * (C) Copyright 2009-2011 -
3 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * LTTng nice 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 nice_get_size(size_t offset)
20{
21 size_t size = 0;
22
23 size += lib_ring_buffer_align(offset, ltt_alignof(int));
24 size += sizeof(int);
25 return size;
26}
27
28static
29void nice_record(struct lttng_ctx_field *field,
30 struct lib_ring_buffer_ctx *ctx,
31 struct ltt_channel *chan)
32{
33 int nice;
34
35 nice = task_nice(current);
36 lib_ring_buffer_align_ctx(ctx, ltt_alignof(nice));
37 chan->ops->event_write(ctx, &nice, sizeof(nice));
38}
39
40int lttng_add_nice_to_ctx(struct lttng_ctx **ctx)
41{
42 struct lttng_ctx_field *field;
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43
44 field = lttng_append_context(ctx);
45 if (!field)
09fec6b4 46 return -ENOMEM;
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47 if (lttng_find_context(*ctx, "nice")) {
48 lttng_remove_context_field(ctx, field);
49 return -EEXIST;
50 }
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51 field->event_field.name = "nice";
52 field->event_field.type.atype = atype_integer;
53 field->event_field.type.u.basic.integer.size = sizeof(int) * CHAR_BIT;
54 field->event_field.type.u.basic.integer.alignment = ltt_alignof(int) * CHAR_BIT;
55 field->event_field.type.u.basic.integer.signedness = is_signed_type(int);
56 field->event_field.type.u.basic.integer.reverse_byte_order = 0;
57 field->event_field.type.u.basic.integer.base = 10;
58 field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
59 field->get_size = nice_get_size;
60 field->record = nice_record;
61 wrapper_vmalloc_sync_all();
62 return 0;
63}
64EXPORT_SYMBOL_GPL(lttng_add_nice_to_ctx);
65
66MODULE_LICENSE("GPL and additional rights");
67MODULE_AUTHOR("Mathieu Desnoyers");
68MODULE_DESCRIPTION("Linux Trace Toolkit Nice Context");
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