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 <lttng/events-internal.h>
15 #include <ringbuffer/frontend_types.h>
16 #include <wrapper/vmalloc.h>
17 #include <lttng/tracer.h>
18 #include <lttng/endian.h>
21 size_t procname_get_size(void *priv
, struct lttng_kernel_probe_ctx
*probe_ctx
, size_t offset
)
25 size
+= sizeof(current
->comm
);
30 * Racy read of procname. We simply copy its whole array size.
31 * Races with /proc/<task>/procname write only.
32 * Otherwise having to take a mutex for each event is cumbersome and
33 * could lead to crash in IRQ context and deadlock of the lockdep tracer.
36 void procname_record(void *priv
, struct lttng_kernel_probe_ctx
*probe_ctx
,
37 struct lttng_kernel_ring_buffer_ctx
*ctx
,
38 struct lttng_kernel_channel_buffer
*chan
)
40 chan
->ops
->event_write(ctx
, current
->comm
, sizeof(current
->comm
), 1);
44 void procname_get_value(void *priv
,
45 struct lttng_kernel_probe_ctx
*lttng_probe_ctx
,
46 struct lttng_ctx_value
*value
)
48 value
->u
.str
= current
->comm
;
51 static const struct lttng_kernel_ctx_field
*ctx_field
= lttng_kernel_static_ctx_field(
52 lttng_kernel_static_event_field("procname",
53 lttng_kernel_static_type_array_text(sizeof(current
->comm
)),
60 int lttng_add_procname_to_ctx(struct lttng_kernel_ctx
**ctx
)
64 if (lttng_kernel_find_context(*ctx
, ctx_field
->event_field
->name
))
66 ret
= lttng_kernel_context_append(ctx
, ctx_field
);
67 wrapper_vmalloc_sync_mappings();
70 EXPORT_SYMBOL_GPL(lttng_add_procname_to_ctx
);