1e7cdeab8b5a657c59b4b926f7ebbb09813577c3
[lttng-modules.git] / lttng-context-migratable.c
1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
2 *
3 * lttng-context-migratable.c
4 *
5 * LTTng migratable context.
6 *
7 * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 */
9
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/sched.h>
13 #include <linux/irqflags.h>
14 #include <lttng-events.h>
15 #include <ringbuffer/frontend_types.h>
16 #include <wrapper/vmalloc.h>
17 #include <lttng-tracer.h>
18
19 static
20 size_t migratable_get_size(size_t offset)
21 {
22 size_t size = 0;
23
24 size += lib_ring_buffer_align(offset, lttng_alignof(uint8_t));
25 size += sizeof(uint8_t);
26 return size;
27 }
28
29 static
30 void migratable_record(struct lttng_ctx_field *field,
31 struct lib_ring_buffer_ctx *ctx,
32 struct lttng_channel *chan)
33 {
34 uint8_t migratable = !current->migrate_disable;
35
36 lib_ring_buffer_align_ctx(ctx, lttng_alignof(migratable));
37 chan->ops->event_write(ctx, &migratable, sizeof(migratable));
38 }
39
40 static
41 void migratable_get_value(struct lttng_ctx_field *field,
42 struct lttng_probe_ctx *lttng_probe_ctx,
43 union lttng_ctx_value *value)
44 {
45 value->s64 = !current->migrate_disable;
46 }
47
48 int lttng_add_migratable_to_ctx(struct lttng_ctx **ctx)
49 {
50 struct lttng_ctx_field *field;
51
52 field = lttng_append_context(ctx);
53 if (!field)
54 return -ENOMEM;
55 if (lttng_find_context(*ctx, "migratable")) {
56 lttng_remove_context_field(ctx, field);
57 return -EEXIST;
58 }
59 field->event_field.name = "migratable";
60 field->event_field.type.atype = atype_integer;
61 field->event_field.type.u.integer.size = sizeof(uint8_t) * CHAR_BIT;
62 field->event_field.type.u.integer.alignment = lttng_alignof(uint8_t) * CHAR_BIT;
63 field->event_field.type.u.integer.signedness = lttng_is_signed_type(uint8_t);
64 field->event_field.type.u.integer.reverse_byte_order = 0;
65 field->event_field.type.u.integer.base = 10;
66 field->event_field.type.u.integer.encoding = lttng_encode_none;
67 field->get_size = migratable_get_size;
68 field->record = migratable_record;
69 field->get_value = migratable_get_value;
70 lttng_context_update(*ctx);
71 wrapper_vmalloc_sync_mappings();
72 return 0;
73 }
74 EXPORT_SYMBOL_GPL(lttng_add_migratable_to_ctx);
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