Commit | Line | Data |
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c1ef86f0 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
c1ef86f0 | 3 | * |
e92f3e28 MD |
4 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
5 | * | |
c0c0989a | 6 | * LTTng UST vpid context. |
c1ef86f0 MD |
7 | */ |
8 | ||
3fbec7dc | 9 | #define _LGPL_SOURCE |
9af5d97a | 10 | #include <limits.h> |
b4051ad8 | 11 | #include <stddef.h> |
c1ef86f0 MD |
12 | #include <sys/types.h> |
13 | #include <unistd.h> | |
4318ae1b MD |
14 | #include <lttng/ust-events.h> |
15 | #include <lttng/ust-tracer.h> | |
0466ac28 | 16 | #include <lttng/ringbuffer-context.h> |
c1ef86f0 | 17 | |
fc80554e MJ |
18 | #include "context-internal.h" |
19 | ||
c1ef86f0 MD |
20 | /* |
21 | * We cache the result to ensure we don't trigger a system call for | |
22 | * each event. | |
23 | */ | |
24 | static pid_t cached_vpid; | |
25 | ||
26 | static inline | |
98357ffd | 27 | pid_t wrapper_getvpid(void) |
c1ef86f0 | 28 | { |
98357ffd MD |
29 | pid_t vpid; |
30 | ||
31 | vpid = CMM_LOAD_SHARED(cached_vpid); | |
32 | if (caa_unlikely(!vpid)) { | |
33 | vpid = getpid(); | |
34 | CMM_STORE_SHARED(cached_vpid, vpid); | |
35 | } | |
36 | return vpid; | |
c1ef86f0 MD |
37 | } |
38 | ||
39 | /* | |
40 | * Upon fork or clone, the PID assigned to our thread is not the same as | |
41 | * we kept in cache. | |
42 | */ | |
43 | void lttng_context_vpid_reset(void) | |
44 | { | |
98357ffd | 45 | CMM_STORE_SHARED(cached_vpid, 0); |
c1ef86f0 | 46 | } |
c1ef86f0 MD |
47 | |
48 | static | |
2208d8b5 MJ |
49 | size_t vpid_get_size(struct lttng_ust_ctx_field *field __attribute__((unused)), |
50 | size_t offset) | |
c1ef86f0 MD |
51 | { |
52 | size_t size = 0; | |
53 | ||
dc325c1d | 54 | size += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(pid_t)); |
c1ef86f0 MD |
55 | size += sizeof(pid_t); |
56 | return size; | |
57 | } | |
58 | ||
59 | static | |
2208d8b5 | 60 | void vpid_record(struct lttng_ust_ctx_field *field __attribute__((unused)), |
4cfec15c | 61 | struct lttng_ust_lib_ring_buffer_ctx *ctx, |
e7bc0ef6 | 62 | struct lttng_ust_channel_buffer *chan) |
c1ef86f0 | 63 | { |
98357ffd | 64 | pid_t vpid = wrapper_getvpid(); |
c1ef86f0 | 65 | |
8936b6c0 | 66 | chan->ops->event_write(ctx, &vpid, sizeof(vpid), lttng_ust_rb_alignof(vpid)); |
c1ef86f0 MD |
67 | } |
68 | ||
77aa5901 | 69 | static |
2208d8b5 | 70 | void vpid_get_value(struct lttng_ust_ctx_field *field __attribute__((unused)), |
daacdbfc | 71 | struct lttng_ust_ctx_value *value) |
77aa5901 | 72 | { |
98357ffd | 73 | value->u.s64 = wrapper_getvpid(); |
77aa5901 MD |
74 | } |
75 | ||
daacdbfc | 76 | int lttng_add_vpid_to_ctx(struct lttng_ust_ctx **ctx) |
c1ef86f0 | 77 | { |
daacdbfc | 78 | struct lttng_ust_ctx_field *field; |
a084756d MD |
79 | struct lttng_ust_type_common *type; |
80 | int ret; | |
c1ef86f0 | 81 | |
a084756d | 82 | type = lttng_ust_create_type_integer(sizeof(pid_t) * CHAR_BIT, |
dc325c1d | 83 | lttng_ust_rb_alignof(pid_t) * CHAR_BIT, |
eae3c729 | 84 | lttng_ust_is_signed_type(pid_t), |
a084756d MD |
85 | BYTE_ORDER, 10); |
86 | if (!type) | |
c1ef86f0 | 87 | return -ENOMEM; |
a084756d MD |
88 | field = lttng_append_context(ctx); |
89 | if (!field) { | |
90 | ret = -ENOMEM; | |
91 | goto error_context; | |
92 | } | |
c1ef86f0 | 93 | if (lttng_find_context(*ctx, "vpid")) { |
a084756d MD |
94 | ret = -EEXIST; |
95 | goto error_find_context; | |
c1ef86f0 | 96 | } |
a084756d MD |
97 | field->event_field->name = strdup("vpid"); |
98 | if (!field->event_field->name) { | |
99 | ret = -ENOMEM; | |
100 | goto error_name; | |
101 | } | |
102 | field->event_field->type = type; | |
c1ef86f0 MD |
103 | field->get_size = vpid_get_size; |
104 | field->record = vpid_record; | |
77aa5901 | 105 | field->get_value = vpid_get_value; |
b2cc986a | 106 | lttng_context_update(*ctx); |
c1ef86f0 | 107 | return 0; |
a084756d MD |
108 | |
109 | error_name: | |
110 | error_find_context: | |
111 | lttng_remove_context_field(ctx, field); | |
112 | error_context: | |
113 | lttng_ust_destroy_type(type); | |
114 | return ret; | |
c1ef86f0 | 115 | } |