1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * lttng-context-procname.c
5 * LTTng procname 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 <lttng-events.h>
14 #include <wrapper/ringbuffer/frontend_types.h>
15 #include <lttng-tracer.h>
16 #include <lttng-endian.h>
19 size_t procname_get_size(size_t offset
)
23 size
+= sizeof(current
->comm
);
28 * Racy read of procname. We simply copy its whole array size.
29 * Races with /proc/<task>/procname write only.
30 * Otherwise having to take a mutex for each event is cumbersome and
31 * could lead to crash in IRQ context and deadlock of the lockdep tracer.
34 void procname_record(struct lttng_ctx_field
*field
,
35 struct lib_ring_buffer_ctx
*ctx
,
36 struct lttng_channel
*chan
)
38 chan
->ops
->event_write(ctx
, current
->comm
, sizeof(current
->comm
));
42 void procname_get_value(struct lttng_ctx_field
*field
,
43 struct lttng_probe_ctx
*lttng_probe_ctx
,
44 union lttng_ctx_value
*value
)
46 value
->str
= current
->comm
;
49 static const struct lttng_type procname_array_elem_type
=
50 __type_integer(char, 0, 0, -1, __BYTE_ORDER
, 10, UTF8
);
52 int lttng_add_procname_to_ctx(struct lttng_ctx
**ctx
)
54 struct lttng_ctx_field
*field
;
56 field
= lttng_append_context(ctx
);
59 if (lttng_find_context(*ctx
, "procname")) {
60 lttng_remove_context_field(ctx
, field
);
63 field
->event_field
.name
= "procname";
64 field
->event_field
.type
.atype
= atype_array_nestable
;
65 field
->event_field
.type
.u
.array_nestable
.elem_type
= &procname_array_elem_type
;
66 field
->event_field
.type
.u
.array_nestable
.length
= sizeof(current
->comm
);
67 field
->event_field
.type
.u
.array_nestable
.alignment
= 0;
69 field
->get_size
= procname_get_size
;
70 field
->record
= procname_record
;
71 field
->get_value
= procname_get_value
;
72 lttng_context_update(*ctx
);
75 EXPORT_SYMBOL_GPL(lttng_add_procname_to_ctx
);