1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
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 <wrapper/vmalloc.h>
17 #include <lttng-tracer.h>
20 size_t vppid_get_size(size_t offset
)
24 size
+= lib_ring_buffer_align(offset
, lttng_alignof(pid_t
));
25 size
+= sizeof(pid_t
);
30 void vppid_record(struct lttng_ctx_field
*field
,
31 struct lib_ring_buffer_ctx
*ctx
,
32 struct lttng_channel
*chan
)
34 struct task_struct
*parent
;
38 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
39 * the current thread nsproxy to perform the lookup.
43 * TODO: when we eventually add RCU subsystem instrumentation,
44 * taking the rcu read lock here will trigger RCU tracing
45 * recursively. We should modify the kernel synchronization so
46 * it synchronizes both for RCU and RCU sched, and rely on
47 * rcu_read_lock_sched_notrace.
51 parent
= rcu_dereference(current
->real_parent
);
52 if (!current
->nsproxy
)
55 vppid
= task_tgid_vnr(parent
);
57 lib_ring_buffer_align_ctx(ctx
, lttng_alignof(vppid
));
58 chan
->ops
->event_write(ctx
, &vppid
, sizeof(vppid
));
62 void vppid_get_value(struct lttng_ctx_field
*field
,
63 struct lttng_probe_ctx
*lttng_probe_ctx
,
64 union lttng_ctx_value
*value
)
66 struct task_struct
*parent
;
70 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
71 * the current thread nsproxy to perform the lookup.
75 * TODO: when we eventually add RCU subsystem instrumentation,
76 * taking the rcu read lock here will trigger RCU tracing
77 * recursively. We should modify the kernel synchronization so
78 * it synchronizes both for RCU and RCU sched, and rely on
79 * rcu_read_lock_sched_notrace.
83 parent
= rcu_dereference(current
->real_parent
);
84 if (!current
->nsproxy
)
87 vppid
= task_tgid_vnr(parent
);
92 int lttng_add_vppid_to_ctx(struct lttng_ctx
**ctx
)
94 struct lttng_ctx_field
*field
;
96 field
= lttng_append_context(ctx
);
99 if (lttng_find_context(*ctx
, "vppid")) {
100 lttng_remove_context_field(ctx
, field
);
103 field
->event_field
.name
= "vppid";
104 field
->event_field
.type
.atype
= atype_integer
;
105 field
->event_field
.type
.u
.basic
.integer
.size
= sizeof(pid_t
) * CHAR_BIT
;
106 field
->event_field
.type
.u
.basic
.integer
.alignment
= lttng_alignof(pid_t
) * CHAR_BIT
;
107 field
->event_field
.type
.u
.basic
.integer
.signedness
= lttng_is_signed_type(pid_t
);
108 field
->event_field
.type
.u
.basic
.integer
.reverse_byte_order
= 0;
109 field
->event_field
.type
.u
.basic
.integer
.base
= 10;
110 field
->event_field
.type
.u
.basic
.integer
.encoding
= lttng_encode_none
;
111 field
->get_size
= vppid_get_size
;
112 field
->record
= vppid_record
;
113 field
->get_value
= vppid_get_value
;
114 lttng_context_update(*ctx
);
115 wrapper_vmalloc_sync_all();
118 EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx
);
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