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3b402b40 MD |
1 | /* |
2 | * (C) Copyright 2009-2011 - | |
3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | * | |
5 | * LTTng UST vtid context. | |
6 | * | |
7 | * Dual LGPL v2.1/GPL v2 license. | |
8 | */ | |
9 | ||
10 | #include <sys/types.h> | |
11 | #include <unistd.h> | |
12 | #include <ust/lttng-events.h> | |
13 | #include <ust/lttng-tracer.h> | |
14 | #include <ust/ringbuffer-config.h> | |
15 | ||
16 | #ifdef __linux__ | |
17 | #include <syscall.h> | |
18 | #endif | |
19 | ||
20 | #if defined(_syscall0) | |
21 | _syscall0(pid_t, gettid) | |
22 | #elif defined(__NR_gettid) | |
23 | static inline pid_t gettid(void) | |
24 | { | |
25 | return syscall(__NR_gettid); | |
26 | } | |
27 | #else | |
28 | #warning "use pid as tid" | |
29 | static inline pid_t gettid(void) | |
30 | { | |
31 | return getpid(); | |
32 | } | |
33 | #endif | |
34 | ||
35 | /* | |
36 | * We cache the result to ensure we don't trigger a system call for | |
37 | * each event. | |
38 | */ | |
39 | static __thread pid_t cached_vtid; | |
40 | ||
41 | static | |
42 | size_t vtid_get_size(size_t offset) | |
43 | { | |
44 | size_t size = 0; | |
45 | ||
46 | size += lib_ring_buffer_align(offset, lttng_alignof(pid_t)); | |
47 | size += sizeof(pid_t); | |
48 | return size; | |
49 | } | |
50 | ||
51 | static | |
52 | void vtid_record(struct lttng_ctx_field *field, | |
53 | struct lib_ring_buffer_ctx *ctx, | |
54 | struct ltt_channel *chan) | |
55 | { | |
56 | if (unlikely(!cached_vtid)) | |
57 | cached_vtid = gettid(); | |
58 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(cached_vtid)); | |
59 | chan->ops->event_write(ctx, &cached_vtid, sizeof(cached_vtid)); | |
60 | } | |
61 | ||
62 | int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx) | |
63 | { | |
64 | struct lttng_ctx_field *field; | |
65 | ||
66 | field = lttng_append_context(ctx); | |
67 | if (!field) | |
68 | return -ENOMEM; | |
69 | if (lttng_find_context(*ctx, "vtid")) { | |
70 | lttng_remove_context_field(ctx, field); | |
71 | return -EEXIST; | |
72 | } | |
73 | field->event_field.name = "vtid"; | |
74 | field->event_field.type.atype = atype_integer; | |
75 | field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT; | |
76 | field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT; | |
77 | field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t); | |
78 | field->event_field.type.u.basic.integer.reverse_byte_order = 0; | |
79 | field->event_field.type.u.basic.integer.base = 10; | |
80 | field->event_field.type.u.basic.integer.encoding = lttng_encode_none; | |
81 | field->get_size = vtid_get_size; | |
82 | field->record = vtid_record; | |
83 | return 0; | |
84 | } |