1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * lttng-context-vppid.c
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/syscalls.h>
14 #include <lttng-events.h>
15 #include <wrapper/ringbuffer/frontend_types.h>
16 #include <lttng-tracer.h>
19 size_t vppid_get_size(size_t offset
)
23 size
+= lib_ring_buffer_align(offset
, lttng_alignof(pid_t
));
24 size
+= sizeof(pid_t
);
29 void vppid_record(struct lttng_ctx_field
*field
,
30 struct lib_ring_buffer_ctx
*ctx
,
31 struct lttng_channel
*chan
)
33 struct task_struct
*parent
;
37 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
38 * the current thread nsproxy to perform the lookup.
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.
50 parent
= rcu_dereference(current
->real_parent
);
51 if (!current
->nsproxy
)
54 vppid
= task_tgid_vnr(parent
);
56 lib_ring_buffer_align_ctx(ctx
, lttng_alignof(vppid
));
57 chan
->ops
->event_write(ctx
, &vppid
, sizeof(vppid
));
61 void vppid_get_value(struct lttng_ctx_field
*field
,
62 struct lttng_probe_ctx
*lttng_probe_ctx
,
63 union lttng_ctx_value
*value
)
65 struct task_struct
*parent
;
69 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
70 * the current thread nsproxy to perform the lookup.
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.
82 parent
= rcu_dereference(current
->real_parent
);
83 if (!current
->nsproxy
)
86 vppid
= task_tgid_vnr(parent
);
91 int lttng_add_vppid_to_ctx(struct lttng_ctx
**ctx
)
93 struct lttng_ctx_field
*field
;
95 field
= lttng_append_context(ctx
);
98 if (lttng_find_context(*ctx
, "vppid")) {
99 lttng_remove_context_field(ctx
, field
);
102 field
->event_field
.name
= "vppid";
103 field
->event_field
.type
.atype
= atype_integer
;
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
;
110 field
->get_size
= vppid_get_size
;
111 field
->record
= vppid_record
;
112 field
->get_value
= vppid_get_value
;
113 lttng_context_update(*ctx
);
116 EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx
);
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