[lttng-modules.git] / src / lttng-context-hostname.c

/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
 *
 * lttng-context-hostname.c
 *
 * LTTng hostname context.
 *
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/utsname.h>
#include <lttng/events.h>
#include <lttng/events-internal.h>
#include <ringbuffer/frontend_types.h>
#include <wrapper/vmalloc.h>
#include <lttng/tracer.h>

#define LTTNG_HOSTNAME_CTX_LEN	(__NEW_UTS_LEN + 1)

static
size_t hostname_get_size(void *priv, struct lttng_kernel_probe_ctx *probe_ctx, size_t offset)
{
	size_t size = 0;

	size += LTTNG_HOSTNAME_CTX_LEN;
	return size;
}

static
void hostname_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx,
		 struct lttng_kernel_ring_buffer_ctx *ctx,
		 struct lttng_channel *chan)
{
	struct nsproxy *nsproxy;
	struct uts_namespace *ns;
	char *hostname;

	/*
	 * No need to take the RCU read-side lock to read current
	 * nsproxy. (documented in nsproxy.h)
	 */
	nsproxy = current->nsproxy;
	if (nsproxy) {
		ns = nsproxy->uts_ns;
		hostname = ns->name.nodename;
		chan->ops->event_write(ctx, hostname,
				LTTNG_HOSTNAME_CTX_LEN);
	} else {
		chan->ops->event_memset(ctx, 0,
				LTTNG_HOSTNAME_CTX_LEN);
	}
}

static
void hostname_get_value(void *priv,
		struct lttng_kernel_probe_ctx *lttng_probe_ctx,
		struct lttng_ctx_value *value)
{
	struct nsproxy *nsproxy;
	struct uts_namespace *ns;
	char *hostname;

	/*
	 * No need to take the RCU read-side lock to read current
	 * nsproxy. (documented in nsproxy.h)
	 */
	nsproxy = current->nsproxy;
	if (nsproxy) {
		ns = nsproxy->uts_ns;
		hostname = ns->name.nodename;
	} else {
		hostname = "";
	}
	value->u.str = hostname;
}

static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	lttng_kernel_static_event_field("hostname",
		lttng_kernel_static_type_array_text(LTTNG_HOSTNAME_CTX_LEN),
		false, false, false),
	hostname_get_size,
	hostname_record,
	hostname_get_value,
	NULL, NULL);

int lttng_add_hostname_to_ctx(struct lttng_kernel_ctx **ctx)
{
	int ret;

	if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
		return -EEXIST;
	ret = lttng_kernel_context_append(ctx, ctx_field);
	wrapper_vmalloc_sync_mappings();
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx);
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
9f36eaed	2	*
975da2c0 JD	3	* lttng-context-hostname.c
	4	*
	5	* LTTng hostname context.
	6	*
	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
975da2c0 JD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/sched.h>
	13	#include <linux/utsname.h>
2df37e95	14	#include <lttng/events.h>
437d5aa5	15	#include <lttng/events-internal.h>
24591303	16	#include <ringbuffer/frontend_types.h>
241ae9a8	17	#include <wrapper/vmalloc.h>
2df37e95	18	#include <lttng/tracer.h>
975da2c0 JD	19
	20	#define LTTNG_HOSTNAME_CTX_LEN (__NEW_UTS_LEN + 1)
	21
	22	static
a92e844e	23	size_t hostname_get_size(void priv, struct lttng_kernel_probe_ctx probe_ctx, size_t offset)
975da2c0 JD	24	{
	25	size_t size = 0;
	26
	27	size += LTTNG_HOSTNAME_CTX_LEN;
	28	return size;
	29	}
	30
	31	static
a92e844e	32	void hostname_record(void priv, struct lttng_kernel_probe_ctx probe_ctx,
8a57ec02	33	struct lttng_kernel_ring_buffer_ctx *ctx,
975da2c0 JD	34	struct lttng_channel *chan)
	35	{
	36	struct nsproxy *nsproxy;
	37	struct uts_namespace *ns;
	38	char *hostname;
	39
3d0d43db MD	40	/*
	41	* No need to take the RCU read-side lock to read current
	42	* nsproxy. (documented in nsproxy.h)
	43	*/
	44	nsproxy = current->nsproxy;
975da2c0 JD	45	if (nsproxy) {
	46	ns = nsproxy->uts_ns;
	47	hostname = ns->name.nodename;
	48	chan->ops->event_write(ctx, hostname,
	49	LTTNG_HOSTNAME_CTX_LEN);
	50	} else {
	51	chan->ops->event_memset(ctx, 0,
	52	LTTNG_HOSTNAME_CTX_LEN);
	53	}
975da2c0 JD	54	}
975da2c0 JD	55
f127e61e	56	static
2dc781e0	57	void hostname_get_value(void *priv,
a92e844e	58	struct lttng_kernel_probe_ctx *lttng_probe_ctx,
2dc781e0	59	struct lttng_ctx_value *value)
f127e61e MD	60	{
	61	struct nsproxy *nsproxy;
	62	struct uts_namespace *ns;
	63	char *hostname;
	64
	65	/*
	66	* No need to take the RCU read-side lock to read current
	67	* nsproxy. (documented in nsproxy.h)
	68	*/
	69	nsproxy = current->nsproxy;
	70	if (nsproxy) {
	71	ns = nsproxy->uts_ns;
	72	hostname = ns->name.nodename;
	73	} else {
	74	hostname = "";
	75	}
2dc781e0	76	value->u.str = hostname;
f127e61e MD	77	}
f127e61e MD	78
437d5aa5 MD	79	static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	80	lttng_kernel_static_event_field("hostname",
	81	lttng_kernel_static_type_array_text(LTTNG_HOSTNAME_CTX_LEN),
	82	false, false, false),
	83	hostname_get_size,
437d5aa5 MD	84	hostname_record,
	85	hostname_get_value,
	86	NULL, NULL);
ceabb767	87
437d5aa5	88	int lttng_add_hostname_to_ctx(struct lttng_kernel_ctx **ctx)
975da2c0	89	{
437d5aa5	90	int ret;
975da2c0	91
437d5aa5	92	if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
975da2c0	93	return -EEXIST;
437d5aa5	94	ret = lttng_kernel_context_append(ctx, ctx_field);
263b6c88	95	wrapper_vmalloc_sync_mappings();
437d5aa5	96	return ret;
975da2c0 JD	97	}
975da2c0 JD	98	EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx);