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

/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
 *
 * lttng-context-ppid.c
 *
 * LTTng PPID 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/syscalls.h>
#include <lttng/events.h>
#include <lttng/events-internal.h>
#include <ringbuffer/frontend_types.h>
#include <wrapper/vmalloc.h>
#include <lttng/tracer.h>

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

	size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
	size += sizeof(pid_t);
	return size;
}

static
void ppid_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx,
		 struct lttng_kernel_ring_buffer_ctx *ctx,
		 struct lttng_channel *chan)
{
	pid_t ppid;

	/*
	 * TODO: when we eventually add RCU subsystem instrumentation,
	 * taking the rcu read lock here will trigger RCU tracing
	 * recursively. We should modify the kernel synchronization so
	 * it synchronizes both for RCU and RCU sched, and rely on
	 * rcu_read_lock_sched_notrace.
	 */
	rcu_read_lock();
	ppid = task_tgid_nr(current->real_parent);
	rcu_read_unlock();
	lib_ring_buffer_align_ctx(ctx, lttng_alignof(ppid));
	chan->ops->event_write(ctx, &ppid, sizeof(ppid));
}

static
void ppid_get_value(void *priv,
		struct lttng_kernel_probe_ctx *lttng_probe_ctx,
		struct lttng_ctx_value *value)
{
	pid_t ppid;

	/*
	 * TODO: when we eventually add RCU subsystem instrumentation,
	 * taking the rcu read lock here will trigger RCU tracing
	 * recursively. We should modify the kernel synchronization so
	 * it synchronizes both for RCU and RCU sched, and rely on
	 * rcu_read_lock_sched_notrace.
	 */
	rcu_read_lock();
	ppid = task_tgid_nr(current->real_parent);
	rcu_read_unlock();
	value->u.s64 = ppid;
}

static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	lttng_kernel_static_event_field("ppid",
		lttng_kernel_static_type_integer_from_type(pid_t, __BYTE_ORDER, 10),
		false, false, false),
	ppid_get_size,
	ppid_record,
	ppid_get_value,
	NULL, NULL);

int lttng_add_ppid_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_ppid_to_ctx);
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
9f36eaed	2	*
886d51a3	3	* lttng-context-ppid.c
b64bc438 MD	4	*
	5	* LTTng PPID context.
	6	*
886d51a3	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
b64bc438 MD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/sched.h>
	13	#include <linux/syscalls.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>
b64bc438 MD	19
b64bc438 MD	20	static
a92e844e	21	size_t ppid_get_size(void priv, struct lttng_kernel_probe_ctx probe_ctx, size_t offset)
b64bc438 MD	22	{
	23	size_t size = 0;
	24
a90917c3	25	size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
b64bc438 MD	26	size += sizeof(pid_t);
	27	return size;
	28	}
	29
	30	static
a92e844e	31	void ppid_record(void priv, struct lttng_kernel_probe_ctx probe_ctx,
8a57ec02	32	struct lttng_kernel_ring_buffer_ctx *ctx,
a90917c3	33	struct lttng_channel *chan)
b64bc438 MD	34	{
	35	pid_t ppid;
	36
1638c9b4 MD	37	/*
	38	* TODO: when we eventually add RCU subsystem instrumentation,
	39	* taking the rcu read lock here will trigger RCU tracing
	40	* recursively. We should modify the kernel synchronization so
	41	* it synchronizes both for RCU and RCU sched, and rely on
	42	* rcu_read_lock_sched_notrace.
	43	*/
b64bc438 MD	44	rcu_read_lock();
	45	ppid = task_tgid_nr(current->real_parent);
	46	rcu_read_unlock();
a90917c3	47	lib_ring_buffer_align_ctx(ctx, lttng_alignof(ppid));
b64bc438 MD	48	chan->ops->event_write(ctx, &ppid, sizeof(ppid));
	49	}
	50
f127e61e	51	static
2dc781e0	52	void ppid_get_value(void *priv,
a92e844e	53	struct lttng_kernel_probe_ctx *lttng_probe_ctx,
2dc781e0	54	struct lttng_ctx_value *value)
f127e61e MD	55	{
	56	pid_t ppid;
	57
	58	/*
	59	* TODO: when we eventually add RCU subsystem instrumentation,
	60	* taking the rcu read lock here will trigger RCU tracing
	61	* recursively. We should modify the kernel synchronization so
	62	* it synchronizes both for RCU and RCU sched, and rely on
	63	* rcu_read_lock_sched_notrace.
	64	*/
	65	rcu_read_lock();
	66	ppid = task_tgid_nr(current->real_parent);
	67	rcu_read_unlock();
2dc781e0	68	value->u.s64 = ppid;
f127e61e MD	69	}
f127e61e MD	70
437d5aa5 MD	71	static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	72	lttng_kernel_static_event_field("ppid",
	73	lttng_kernel_static_type_integer_from_type(pid_t, __BYTE_ORDER, 10),
	74	false, false, false),
	75	ppid_get_size,
437d5aa5 MD	76	ppid_record,
	77	ppid_get_value,
	78	NULL, NULL);
	79
	80	int lttng_add_ppid_to_ctx(struct lttng_kernel_ctx **ctx)
b64bc438	81	{
437d5aa5	82	int ret;
b64bc438	83
437d5aa5	84	if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
44252f0f	85	return -EEXIST;
437d5aa5	86	ret = lttng_kernel_context_append(ctx, ctx_field);
263b6c88	87	wrapper_vmalloc_sync_mappings();
437d5aa5	88	return ret;
b64bc438 MD	89	}
b64bc438 MD	90	EXPORT_SYMBOL_GPL(lttng_add_ppid_to_ctx);