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-ppid.c |
b64bc438 MD |
4 | * |
5 | * LTTng PPID 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 | |
ea2d95e4 | 21 | size_t ppid_get_size(void *priv, struct lttng_probe_ctx *probe_ctx, size_t offset) |
b64bc438 MD |
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 | |
ea2d95e4 | 31 | void ppid_record(void *priv, struct lttng_probe_ctx *probe_ctx, |
b64bc438 | 32 | struct lib_ring_buffer_ctx *ctx, |
a90917c3 | 33 | struct lttng_channel *chan) |
b64bc438 MD |
34 | { |
35 | pid_t ppid; | |
36 | ||
1638c9b4 MD |
37 | /* |
38 | * TODO: when we eventually add RCU subsystem instrumentation, | |
39 | * taking the rcu read lock here will trigger RCU tracing | |
40 | * recursively. We should modify the kernel synchronization so | |
41 | * it synchronizes both for RCU and RCU sched, and rely on | |
42 | * rcu_read_lock_sched_notrace. | |
43 | */ | |
b64bc438 MD |
44 | rcu_read_lock(); |
45 | ppid = task_tgid_nr(current->real_parent); | |
46 | rcu_read_unlock(); | |
a90917c3 | 47 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(ppid)); |
b64bc438 MD |
48 | chan->ops->event_write(ctx, &ppid, sizeof(ppid)); |
49 | } | |
50 | ||
f127e61e | 51 | static |
ea2d95e4 | 52 | void ppid_get_value(void *priv, |
79150a49 | 53 | struct lttng_probe_ctx *lttng_probe_ctx, |
ea2d95e4 | 54 | struct lttng_ctx_value *value) |
f127e61e MD |
55 | { |
56 | pid_t ppid; | |
57 | ||
58 | /* | |
59 | * TODO: when we eventually add RCU subsystem instrumentation, | |
60 | * taking the rcu read lock here will trigger RCU tracing | |
61 | * recursively. We should modify the kernel synchronization so | |
62 | * it synchronizes both for RCU and RCU sched, and rely on | |
63 | * rcu_read_lock_sched_notrace. | |
64 | */ | |
65 | rcu_read_lock(); | |
66 | ppid = task_tgid_nr(current->real_parent); | |
67 | rcu_read_unlock(); | |
ea2d95e4 | 68 | value->u.s64 = ppid; |
f127e61e MD |
69 | } |
70 | ||
437d5aa5 MD |
71 | static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field( |
72 | lttng_kernel_static_event_field("ppid", | |
73 | lttng_kernel_static_type_integer_from_type(pid_t, __BYTE_ORDER, 10), | |
74 | false, false, false), | |
75 | ppid_get_size, | |
437d5aa5 MD |
76 | ppid_record, |
77 | ppid_get_value, | |
78 | NULL, NULL); | |
79 | ||
80 | int lttng_add_ppid_to_ctx(struct lttng_kernel_ctx **ctx) | |
b64bc438 | 81 | { |
437d5aa5 | 82 | int ret; |
b64bc438 | 83 | |
437d5aa5 | 84 | if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name)) |
44252f0f | 85 | return -EEXIST; |
437d5aa5 | 86 | ret = lttng_kernel_context_append(ctx, ctx_field); |
263b6c88 | 87 | wrapper_vmalloc_sync_mappings(); |
437d5aa5 | 88 | return ret; |
b64bc438 MD |
89 | } |
90 | EXPORT_SYMBOL_GPL(lttng_add_ppid_to_ctx); |