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> | |
2df37e95 | 14 | #include <lttng/events.h> |
437d5aa5 | 15 | #include <lttng/events-internal.h> |
24591303 | 16 | #include <ringbuffer/frontend_types.h> |
241ae9a8 | 17 | #include <wrapper/vmalloc.h> |
2df37e95 | 18 | #include <lttng/tracer.h> |
b64bc438 MD |
19 | |
20 | static | |
21 | size_t vppid_get_size(size_t offset) | |
22 | { | |
23 | size_t size = 0; | |
24 | ||
a90917c3 | 25 | size += lib_ring_buffer_align(offset, lttng_alignof(pid_t)); |
b64bc438 MD |
26 | size += sizeof(pid_t); |
27 | return size; | |
28 | } | |
29 | ||
30 | static | |
437d5aa5 | 31 | void vppid_record(struct lttng_kernel_ctx_field *field, |
b64bc438 | 32 | struct lib_ring_buffer_ctx *ctx, |
a90917c3 | 33 | struct lttng_channel *chan) |
b64bc438 | 34 | { |
90f96adf | 35 | struct task_struct *parent; |
b64bc438 MD |
36 | pid_t vppid; |
37 | ||
90f96adf | 38 | /* |
de544ea5 MD |
39 | * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses |
40 | * the current thread nsproxy to perform the lookup. | |
90f96adf | 41 | */ |
1638c9b4 MD |
42 | |
43 | /* | |
44 | * TODO: when we eventually add RCU subsystem instrumentation, | |
45 | * taking the rcu read lock here will trigger RCU tracing | |
46 | * recursively. We should modify the kernel synchronization so | |
47 | * it synchronizes both for RCU and RCU sched, and rely on | |
48 | * rcu_read_lock_sched_notrace. | |
49 | */ | |
50 | ||
b64bc438 | 51 | rcu_read_lock(); |
90f96adf | 52 | parent = rcu_dereference(current->real_parent); |
de544ea5 | 53 | if (!current->nsproxy) |
90f96adf MD |
54 | vppid = 0; |
55 | else | |
56 | vppid = task_tgid_vnr(parent); | |
b64bc438 | 57 | rcu_read_unlock(); |
a90917c3 | 58 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid)); |
b64bc438 MD |
59 | chan->ops->event_write(ctx, &vppid, sizeof(vppid)); |
60 | } | |
61 | ||
f127e61e | 62 | static |
437d5aa5 | 63 | void vppid_get_value(struct lttng_kernel_ctx_field *field, |
79150a49 | 64 | struct lttng_probe_ctx *lttng_probe_ctx, |
f127e61e MD |
65 | union lttng_ctx_value *value) |
66 | { | |
67 | struct task_struct *parent; | |
68 | pid_t vppid; | |
69 | ||
70 | /* | |
71 | * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses | |
72 | * the current thread nsproxy to perform the lookup. | |
73 | */ | |
74 | ||
75 | /* | |
76 | * TODO: when we eventually add RCU subsystem instrumentation, | |
77 | * taking the rcu read lock here will trigger RCU tracing | |
78 | * recursively. We should modify the kernel synchronization so | |
79 | * it synchronizes both for RCU and RCU sched, and rely on | |
80 | * rcu_read_lock_sched_notrace. | |
81 | */ | |
82 | ||
83 | rcu_read_lock(); | |
84 | parent = rcu_dereference(current->real_parent); | |
85 | if (!current->nsproxy) | |
86 | vppid = 0; | |
87 | else | |
88 | vppid = task_tgid_vnr(parent); | |
89 | rcu_read_unlock(); | |
90 | value->s64 = vppid; | |
91 | } | |
92 | ||
437d5aa5 MD |
93 | static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field( |
94 | lttng_kernel_static_event_field("vppid", | |
95 | lttng_kernel_static_type_integer_from_type(pid_t, __BYTE_ORDER, 10), | |
96 | false, false, false), | |
97 | vppid_get_size, | |
98 | NULL, | |
99 | vppid_record, | |
100 | vppid_get_value, | |
101 | NULL, NULL); | |
102 | ||
103 | int lttng_add_vppid_to_ctx(struct lttng_kernel_ctx **ctx) | |
b64bc438 | 104 | { |
437d5aa5 | 105 | int ret; |
b64bc438 | 106 | |
437d5aa5 | 107 | if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name)) |
44252f0f | 108 | return -EEXIST; |
437d5aa5 | 109 | ret = lttng_kernel_context_append(ctx, ctx_field); |
263b6c88 | 110 | wrapper_vmalloc_sync_mappings(); |
437d5aa5 | 111 | return ret; |
b64bc438 MD |
112 | } |
113 | EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx); |