2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
5 * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
7 * LTTng UST net namespace context.
13 #include <sys/types.h>
16 #include <lttng/ust-events.h>
17 #include <lttng/ust-tracer.h>
18 #include <lttng/ringbuffer-context.h>
20 #include <urcu/tls-compat.h>
22 #include "context-internal.h"
23 #include "lttng-tracer-core.h"
27 * We cache the result to ensure we don't stat(2) the proc filesystem on
30 static DEFINE_URCU_TLS_INIT(ino_t
, cached_net_ns
, NS_INO_UNINITIALIZED
);
33 ino_t
get_net_ns(void)
38 net_ns
= CMM_LOAD_SHARED(URCU_TLS(cached_net_ns
));
41 * If the cache is populated, do nothing and return the
42 * cached inode number.
44 if (caa_likely(net_ns
!= NS_INO_UNINITIALIZED
))
48 * At this point we have to populate the cache, set the initial
49 * value to NS_INO_UNAVAILABLE (0), if we fail to get the inode
50 * number from the proc filesystem, this is the value we will
53 net_ns
= NS_INO_UNAVAILABLE
;
56 * /proc/thread-self was introduced in kernel v3.17
58 if (stat("/proc/thread-self/ns/net", &sb
) == 0) {
61 char proc_ns_path
[LTTNG_PROC_NS_PATH_MAX
];
63 if (snprintf(proc_ns_path
, LTTNG_PROC_NS_PATH_MAX
,
64 "/proc/self/task/%d/ns/net",
65 lttng_gettid()) >= 0) {
67 if (stat(proc_ns_path
, &sb
) == 0) {
74 * And finally, store the inode number in the cache.
76 CMM_STORE_SHARED(URCU_TLS(cached_net_ns
), net_ns
);
82 * The net namespace can change for 3 reasons
83 * * clone(2) called with CLONE_NEWNET
84 * * setns(2) called with the fd of a different net ns
85 * * unshare(2) called with CLONE_NEWNET
87 void lttng_context_net_ns_reset(void)
89 CMM_STORE_SHARED(URCU_TLS(cached_net_ns
), NS_INO_UNINITIALIZED
);
93 size_t net_ns_get_size(struct lttng_ust_ctx_field
*field
, size_t offset
)
97 size
+= lttng_ust_lib_ring_buffer_align(offset
, lttng_alignof(ino_t
));
98 size
+= sizeof(ino_t
);
103 void net_ns_record(struct lttng_ust_ctx_field
*field
,
104 struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
105 struct lttng_ust_channel_buffer
*chan
)
109 net_ns
= get_net_ns();
110 lttng_ust_lib_ring_buffer_align_ctx(ctx
, lttng_alignof(net_ns
));
111 chan
->ops
->event_write(ctx
, &net_ns
, sizeof(net_ns
));
115 void net_ns_get_value(struct lttng_ust_ctx_field
*field
,
116 struct lttng_ust_ctx_value
*value
)
118 value
->u
.s64
= get_net_ns();
121 int lttng_add_net_ns_to_ctx(struct lttng_ust_ctx
**ctx
)
123 struct lttng_ust_ctx_field
*field
;
124 struct lttng_ust_type_common
*type
;
127 type
= lttng_ust_create_type_integer(sizeof(ino_t
) * CHAR_BIT
,
128 lttng_alignof(ino_t
) * CHAR_BIT
,
129 lttng_ust_is_signed_type(ino_t
),
133 field
= lttng_append_context(ctx
);
138 if (lttng_find_context(*ctx
, "net_ns")) {
140 goto error_find_context
;
142 field
->event_field
->name
= strdup("net_ns");
143 if (!field
->event_field
->name
) {
147 field
->event_field
->type
= type
;
148 field
->get_size
= net_ns_get_size
;
149 field
->record
= net_ns_record
;
150 field
->get_value
= net_ns_get_value
;
151 lttng_context_update(*ctx
);
156 lttng_remove_context_field(ctx
, field
);
158 lttng_ust_destroy_type(type
);
163 * * Force a read (imply TLS fixup for dlopen) of TLS variables.
165 void lttng_fixup_net_ns_tls(void)
167 asm volatile ("" : : "m" (URCU_TLS(cached_net_ns
)));