1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * lttng-context-hostname.c
5 * LTTng hostname context.
7 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/sched.h>
13 #include <linux/utsname.h>
14 #include <lttng-events.h>
15 #include <wrapper/ringbuffer/frontend_types.h>
16 #include <lttng-tracer.h>
18 #define LTTNG_HOSTNAME_CTX_LEN (__NEW_UTS_LEN + 1)
21 size_t hostname_get_size(size_t offset
)
25 size
+= LTTNG_HOSTNAME_CTX_LEN
;
30 void hostname_record(struct lttng_ctx_field
*field
,
31 struct lib_ring_buffer_ctx
*ctx
,
32 struct lttng_channel
*chan
)
34 struct nsproxy
*nsproxy
;
35 struct uts_namespace
*ns
;
39 * No need to take the RCU read-side lock to read current
40 * nsproxy. (documented in nsproxy.h)
42 nsproxy
= current
->nsproxy
;
45 hostname
= ns
->name
.nodename
;
46 chan
->ops
->event_write(ctx
, hostname
,
47 LTTNG_HOSTNAME_CTX_LEN
);
49 chan
->ops
->event_memset(ctx
, 0,
50 LTTNG_HOSTNAME_CTX_LEN
);
55 void hostname_get_value(struct lttng_ctx_field
*field
,
56 struct lttng_probe_ctx
*lttng_probe_ctx
,
57 union lttng_ctx_value
*value
)
59 struct nsproxy
*nsproxy
;
60 struct uts_namespace
*ns
;
64 * No need to take the RCU read-side lock to read current
65 * nsproxy. (documented in nsproxy.h)
67 nsproxy
= current
->nsproxy
;
70 hostname
= ns
->name
.nodename
;
74 value
->str
= hostname
;
77 static const struct lttng_type hostname_array_elem_type
=
78 __type_integer(char, 0, 0, -1, __BYTE_ORDER
, 10, UTF8
);
80 int lttng_add_hostname_to_ctx(struct lttng_ctx
**ctx
)
82 struct lttng_ctx_field
*field
;
84 field
= lttng_append_context(ctx
);
87 if (lttng_find_context(*ctx
, "hostname")) {
88 lttng_remove_context_field(ctx
, field
);
91 field
->event_field
.name
= "hostname";
92 field
->event_field
.type
.atype
= atype_array_nestable
;
93 field
->event_field
.type
.u
.array_nestable
.elem_type
=
94 &hostname_array_elem_type
;
95 field
->event_field
.type
.u
.array_nestable
.length
= LTTNG_HOSTNAME_CTX_LEN
;
96 field
->event_field
.type
.u
.array_nestable
.alignment
= 0;
98 field
->get_size
= hostname_get_size
;
99 field
->record
= hostname_record
;
100 field
->get_value
= hostname_get_value
;
101 lttng_context_update(*ctx
);
104 EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx
);