Commit | Line | Data |
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b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
9f36eaed | 2 | * |
886d51a3 | 3 | * lttng-context-vppid.c |
b64bc438 MD |
4 | * |
5 | * LTTng vPPID context. | |
6 | * | |
886d51a3 | 7 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
b64bc438 MD |
8 | */ |
9 | ||
10 | #include <linux/module.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/sched.h> | |
13 | #include <linux/syscalls.h> | |
241ae9a8 | 14 | #include <lttng-events.h> |
5760f3f4 | 15 | #include <include/ringbuffer/frontend_types.h> |
241ae9a8 | 16 | #include <lttng-tracer.h> |
b64bc438 MD |
17 | |
18 | static | |
19 | size_t vppid_get_size(size_t offset) | |
20 | { | |
21 | size_t size = 0; | |
22 | ||
a90917c3 | 23 | size += lib_ring_buffer_align(offset, lttng_alignof(pid_t)); |
b64bc438 MD |
24 | size += sizeof(pid_t); |
25 | return size; | |
26 | } | |
27 | ||
28 | static | |
29 | void vppid_record(struct lttng_ctx_field *field, | |
30 | struct lib_ring_buffer_ctx *ctx, | |
a90917c3 | 31 | struct lttng_channel *chan) |
b64bc438 | 32 | { |
90f96adf | 33 | struct task_struct *parent; |
b64bc438 MD |
34 | pid_t vppid; |
35 | ||
90f96adf | 36 | /* |
de544ea5 MD |
37 | * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses |
38 | * the current thread nsproxy to perform the lookup. | |
90f96adf | 39 | */ |
1638c9b4 MD |
40 | |
41 | /* | |
42 | * TODO: when we eventually add RCU subsystem instrumentation, | |
43 | * taking the rcu read lock here will trigger RCU tracing | |
44 | * recursively. We should modify the kernel synchronization so | |
45 | * it synchronizes both for RCU and RCU sched, and rely on | |
46 | * rcu_read_lock_sched_notrace. | |
47 | */ | |
48 | ||
b64bc438 | 49 | rcu_read_lock(); |
90f96adf | 50 | parent = rcu_dereference(current->real_parent); |
de544ea5 | 51 | if (!current->nsproxy) |
90f96adf MD |
52 | vppid = 0; |
53 | else | |
54 | vppid = task_tgid_vnr(parent); | |
b64bc438 | 55 | rcu_read_unlock(); |
a90917c3 | 56 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid)); |
b64bc438 MD |
57 | chan->ops->event_write(ctx, &vppid, sizeof(vppid)); |
58 | } | |
59 | ||
f127e61e MD |
60 | static |
61 | void vppid_get_value(struct lttng_ctx_field *field, | |
79150a49 | 62 | struct lttng_probe_ctx *lttng_probe_ctx, |
f127e61e MD |
63 | union lttng_ctx_value *value) |
64 | { | |
65 | struct task_struct *parent; | |
66 | pid_t vppid; | |
67 | ||
68 | /* | |
69 | * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses | |
70 | * the current thread nsproxy to perform the lookup. | |
71 | */ | |
72 | ||
73 | /* | |
74 | * TODO: when we eventually add RCU subsystem instrumentation, | |
75 | * taking the rcu read lock here will trigger RCU tracing | |
76 | * recursively. We should modify the kernel synchronization so | |
77 | * it synchronizes both for RCU and RCU sched, and rely on | |
78 | * rcu_read_lock_sched_notrace. | |
79 | */ | |
80 | ||
81 | rcu_read_lock(); | |
82 | parent = rcu_dereference(current->real_parent); | |
83 | if (!current->nsproxy) | |
84 | vppid = 0; | |
85 | else | |
86 | vppid = task_tgid_vnr(parent); | |
87 | rcu_read_unlock(); | |
88 | value->s64 = vppid; | |
89 | } | |
90 | ||
b64bc438 MD |
91 | int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx) |
92 | { | |
93 | struct lttng_ctx_field *field; | |
b64bc438 MD |
94 | |
95 | field = lttng_append_context(ctx); | |
96 | if (!field) | |
09fec6b4 | 97 | return -ENOMEM; |
44252f0f MD |
98 | if (lttng_find_context(*ctx, "vppid")) { |
99 | lttng_remove_context_field(ctx, field); | |
100 | return -EEXIST; | |
101 | } | |
b64bc438 MD |
102 | field->event_field.name = "vppid"; |
103 | field->event_field.type.atype = atype_integer; | |
ceabb767 MD |
104 | field->event_field.type.u.integer.size = sizeof(pid_t) * CHAR_BIT; |
105 | field->event_field.type.u.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT; | |
106 | field->event_field.type.u.integer.signedness = lttng_is_signed_type(pid_t); | |
107 | field->event_field.type.u.integer.reverse_byte_order = 0; | |
108 | field->event_field.type.u.integer.base = 10; | |
109 | field->event_field.type.u.integer.encoding = lttng_encode_none; | |
b64bc438 MD |
110 | field->get_size = vppid_get_size; |
111 | field->record = vppid_record; | |
f127e61e | 112 | field->get_value = vppid_get_value; |
a9dd15da | 113 | lttng_context_update(*ctx); |
b64bc438 MD |
114 | return 0; |
115 | } | |
116 | EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx); |