lttng: dynamically selectable context information

Events can be augmented with context information. This is dynamically
configurable from the command line.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/lttng/ltt-context.c

+/*
+ * ltt-context.c
+ *
+ * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng trace/channel/event context management.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include "wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
+#include "ltt-events.h"
+#include "ltt-tracer.h"
+
+int lttng_find_context(struct lttng_ctx *ctx, const char *name)
+{
+	unsigned int i;
+
+	for (i = 0; i < ctx->nr_fields; i++) {
+		/* Skip allocated (but non-initialized) contexts */
+		if (!ctx->fields[i].event_field.name)
+			continue;
+		if (!strcmp(ctx->fields[i].event_field.name, name))
+			return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_find_context);
+
+/*
+ * Note: as we append context information, the pointer location may change.
+ */
+struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
+{
+	struct lttng_ctx_field *field;
+	struct lttng_ctx *ctx;
+
+	if (!*ctx_p) {
+		*ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
+		if (!*ctx_p)
+			return NULL;
+	}
+	ctx = *ctx_p;
+	if (ctx->nr_fields + 1 > ctx->allocated_fields) {
+		struct lttng_ctx_field *new_fields;
+
+		ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
+		new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
+		if (!new_fields)
+			return NULL;
+		if (ctx->fields)
+			memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
+		kfree(ctx->fields);
+		ctx->fields = new_fields;
+	}
+	field = &ctx->fields[ctx->nr_fields];
+	ctx->nr_fields++;
+	return field;
+}
+EXPORT_SYMBOL_GPL(lttng_append_context);
+
+/*
+ * Remove last context field.
+ */
+void lttng_remove_context_field(struct lttng_ctx **ctx_p,
+				struct lttng_ctx_field *field)
+{
+	struct lttng_ctx *ctx;
+
+	ctx = *ctx_p;
+	ctx->nr_fields--;
+	WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
+	memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
+}
+EXPORT_SYMBOL_GPL(lttng_remove_context_field);
+
+void lttng_destroy_context(struct lttng_ctx *ctx)
+{
+	int i;
+
+	if (!ctx)
+		return;
+	for (i = 0; i < ctx->nr_fields; i++) {
+		if (ctx->fields[i].destroy)
+			ctx->fields[i].destroy(&ctx->fields[i]);
+	}
+	kfree(ctx->fields);
+	kfree(ctx);
+}

drivers/staging/lttng/lttng-context-nice.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng nice context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t nice_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(int));
+	size += sizeof(int);
+	return size;
+}
+
+static
+void nice_record(struct lttng_ctx_field *field,
+		struct lib_ring_buffer_ctx *ctx,
+		struct ltt_channel *chan)
+{
+	int nice;
+
+	nice = task_nice(current);
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(nice));
+	chan->ops->event_write(ctx, &nice, sizeof(nice));
+}
+
+int lttng_add_nice_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "nice")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "nice";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(int) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(int) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(int);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = nice_get_size;
+	field->record = nice_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_nice_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Nice Context");

drivers/staging/lttng/lttng-context-perf-counters.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng performance monitoring counters (perf-counters) integration module.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/perf_event.h>
+#include <linux/list.h>
+#include <linux/string.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "wrapper/perf.h"
+#include "ltt-tracer.h"
+
+static
+size_t perf_counter_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
+	size += sizeof(uint64_t);
+	return size;
+}
+
+static
+void perf_counter_record(struct lttng_ctx_field *field,
+			 struct lib_ring_buffer_ctx *ctx,
+			 struct ltt_channel *chan)
+{
+	struct perf_event *event;
+	uint64_t value;
+
+	event = field->u.perf_counter->e[ctx->cpu];
+	if (likely(event)) {
+		if (unlikely(event->state == PERF_EVENT_STATE_ERROR)) {
+			value = 0;
+		} else {
+			event->pmu->read(event);
+			value = local64_read(&event->count);
+		}
+	} else {
+		/*
+		 * Perf chooses not to be clever and not to support enabling a
+		 * perf counter before the cpu is brought up. Therefore, we need
+		 * to support having events coming (e.g. scheduler events)
+		 * before the counter is setup. Write an arbitrary 0 in this
+		 * case.
+		 */
+		value = 0;
+	}
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(value));
+	chan->ops->event_write(ctx, &value, sizeof(value));
+}
+
+#if defined(CONFIG_PERF_EVENTS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,0,99))
+static
+void overflow_callback(struct perf_event *event,
+		       struct perf_sample_data *data,
+		       struct pt_regs *regs)
+{
+}
+#else
+static
+void overflow_callback(struct perf_event *event, int nmi,
+		       struct perf_sample_data *data,
+		       struct pt_regs *regs)
+{
+}
+#endif
+
+static
+void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field)
+{
+	struct perf_event **events = field->u.perf_counter->e;
+	int cpu;
+
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		perf_event_release_kernel(events[cpu]);
+	put_online_cpus();
+#ifdef CONFIG_HOTPLUG_CPU
+	unregister_cpu_notifier(&field->u.perf_counter->nb);
+#endif
+	kfree(field->event_field.name);
+	kfree(field->u.perf_counter->attr);
+	kfree(events);
+	kfree(field->u.perf_counter);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/**
+ *	lttng_perf_counter_hp_callback - CPU hotplug callback
+ *	@nb: notifier block
+ *	@action: hotplug action to take
+ *	@hcpu: CPU number
+ *
+ *	Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
+ *
+ * We can setup perf counters when the cpu is online (up prepare seems to be too
+ * soon).
+ */
+static
+int __cpuinit lttng_perf_counter_cpu_hp_callback(struct notifier_block *nb,
+						 unsigned long action,
+						 void *hcpu)
+{
+	unsigned int cpu = (unsigned long) hcpu;
+	struct lttng_perf_counter_field *perf_field =
+		container_of(nb, struct lttng_perf_counter_field, nb);
+	struct perf_event **events = perf_field->e;
+	struct perf_event_attr *attr = perf_field->attr;
+	struct perf_event *pevent;
+
+	if (!perf_field->hp_enable)
+		return NOTIFY_OK;
+
+	switch (action) {
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		pevent = wrapper_perf_event_create_kernel_counter(attr,
+				cpu, NULL, overflow_callback);
+		if (!pevent || IS_ERR(pevent))
+			return NOTIFY_BAD;
+		if (pevent->state == PERF_EVENT_STATE_ERROR) {
+			perf_event_release_kernel(pevent);
+			return NOTIFY_BAD;
+		}
+		barrier();	/* Create perf counter before setting event */
+		events[cpu] = pevent;
+		break;
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		pevent = events[cpu];
+		events[cpu] = NULL;
+		barrier();	/* NULLify event before perf counter teardown */
+		perf_event_release_kernel(pevent);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+#endif
+
+int lttng_add_perf_counter_to_ctx(uint32_t type,
+				  uint64_t config,
+				  const char *name,
+				  struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+	struct lttng_perf_counter_field *perf_field;
+	struct perf_event **events;
+	struct perf_event_attr *attr;
+	int ret;
+	int cpu;
+	char *name_alloc;
+
+	events = kzalloc(num_possible_cpus() * sizeof(*events), GFP_KERNEL);
+	if (!events)
+		return -ENOMEM;
+
+	attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL);
+	if (!attr) {
+		ret = -ENOMEM;
+		goto error_attr;
+	}
+
+	attr->type = type;
+	attr->config = config;
+	attr->size = sizeof(struct perf_event_attr);
+	attr->pinned = 1;
+	attr->disabled = 0;
+
+	perf_field = kzalloc(sizeof(struct lttng_perf_counter_field), GFP_KERNEL);
+	if (!perf_field) {
+		ret = -ENOMEM;
+		goto error_alloc_perf_field;
+	}
+	perf_field->e = events;
+	perf_field->attr = attr;
+
+	name_alloc = kstrdup(name, GFP_KERNEL);
+	if (!name_alloc) {
+		ret = -ENOMEM;
+		goto name_alloc_error;
+	}
+
+	field = lttng_append_context(ctx);
+	if (!field) {
+		ret = -ENOMEM;
+		goto append_context_error;
+	}
+	if (lttng_find_context(*ctx, name_alloc)) {
+		ret = -EEXIST;
+		goto find_error;
+	}
+
+#ifdef CONFIG_HOTPLUG_CPU
+	perf_field->nb.notifier_call =
+		lttng_perf_counter_cpu_hp_callback;
+	perf_field->nb.priority = 0;
+	register_cpu_notifier(&perf_field->nb);
+#endif
+
+	get_online_cpus();
+	for_each_online_cpu(cpu) {
+		events[cpu] = wrapper_perf_event_create_kernel_counter(attr,
+					cpu, NULL, overflow_callback);
+		if (!events[cpu] || IS_ERR(events[cpu])) {
+			ret = -EINVAL;
+			goto counter_error;
+		}
+		if (events[cpu]->state == PERF_EVENT_STATE_ERROR) {
+			ret = -EBUSY;
+			goto counter_busy;
+		}
+	}
+	put_online_cpus();
+
+	field->destroy = lttng_destroy_perf_counter_field;
+
+	field->event_field.name = name_alloc;
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(uint64_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(uint64_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(uint64_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = perf_counter_get_size;
+	field->record = perf_counter_record;
+	field->u.perf_counter = perf_field;
+	perf_field->hp_enable = 1;
+
+	wrapper_vmalloc_sync_all();
+	return 0;
+
+counter_busy:
+counter_error:
+	for_each_online_cpu(cpu) {
+		if (events[cpu] && !IS_ERR(events[cpu]))
+			perf_event_release_kernel(events[cpu]);
+	}
+	put_online_cpus();
+#ifdef CONFIG_HOTPLUG_CPU
+	unregister_cpu_notifier(&perf_field->nb);
+#endif
+find_error:
+	lttng_remove_context_field(ctx, field);
+append_context_error:
+	kfree(name_alloc);
+name_alloc_error:
+	kfree(perf_field);
+error_alloc_perf_field:
+	kfree(attr);
+error_attr:
+	kfree(events);
+	return ret;
+}
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support");

drivers/staging/lttng/lttng-context-pid.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng PID context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t pid_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+	size += sizeof(pid_t);
+	return size;
+}
+
+static
+void pid_record(struct lttng_ctx_field *field,
+		struct lib_ring_buffer_ctx *ctx,
+		struct ltt_channel *chan)
+{
+	pid_t pid;
+
+	pid = task_tgid_nr(current);
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(pid));
+	chan->ops->event_write(ctx, &pid, sizeof(pid));
+}
+
+int lttng_add_pid_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "pid")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "pid";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = pid_get_size;
+	field->record = pid_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_pid_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit PID Context");

drivers/staging/lttng/lttng-context-ppid.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng PPID context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t ppid_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+	size += sizeof(pid_t);
+	return size;
+}
+
+static
+void ppid_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	pid_t ppid;
+
+	rcu_read_lock();
+	ppid = task_tgid_nr(current->real_parent);
+	rcu_read_unlock();
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(ppid));
+	chan->ops->event_write(ctx, &ppid, sizeof(ppid));
+}
+
+int lttng_add_ppid_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "ppid")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "ppid";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = ppid_get_size;
+	field->record = ppid_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_ppid_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit PPID Context");

drivers/staging/lttng/lttng-context-prio.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng priority context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "wrapper/kallsyms.h"
+#include "ltt-tracer.h"
+
+static
+int (*wrapper_task_prio_sym)(struct task_struct *t);
+
+int wrapper_task_prio_init(void)
+{
+	wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio");
+	if (!wrapper_task_prio_sym) {
+		printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static
+size_t prio_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(int));
+	size += sizeof(int);
+	return size;
+}
+
+static
+void prio_record(struct lttng_ctx_field *field,
+		struct lib_ring_buffer_ctx *ctx,
+		struct ltt_channel *chan)
+{
+	int prio;
+
+	prio = wrapper_task_prio_sym(current);
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(prio));
+	chan->ops->event_write(ctx, &prio, sizeof(prio));
+}
+
+int lttng_add_prio_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+	int ret;
+
+	if (!wrapper_task_prio_sym) {
+		ret = wrapper_task_prio_init();
+		if (ret)
+			return ret;
+	}
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "prio")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "prio";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(int) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(int) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(int);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = prio_get_size;
+	field->record = prio_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Priority Context");

drivers/staging/lttng/lttng-context-procname.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng procname context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t procname_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += sizeof(current->comm);
+	return size;
+}
+
+/*
+ * Racy read of procname. We simply copy its whole array size.
+ * Races with /proc/<task>/procname write only.
+ * Otherwise having to take a mutex for each event is cumbersome and
+ * could lead to crash in IRQ context and deadlock of the lockdep tracer.
+ */
+static
+void procname_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	chan->ops->event_write(ctx, current->comm, sizeof(current->comm));
+}
+
+int lttng_add_procname_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "procname")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "procname";
+	field->event_field.type.atype = atype_array;
+	field->event_field.type.u.array.elem_type.atype = atype_integer;
+	field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT;
+	field->event_field.type.u.array.elem_type.u.basic.integer.alignment = ltt_alignof(char) * CHAR_BIT;
+	field->event_field.type.u.array.elem_type.u.basic.integer.signedness = is_signed_type(char);
+	field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.array.elem_type.u.basic.integer.base = 10;
+	field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8;
+	field->event_field.type.u.array.length = sizeof(current->comm);
+
+	field->get_size = procname_get_size;
+	field->record = procname_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_procname_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support");

drivers/staging/lttng/lttng-context-tid.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng TID context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t tid_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+	size += sizeof(pid_t);
+	return size;
+}
+
+static
+void tid_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	pid_t tid;
+
+	tid = task_pid_nr(current);
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(tid));
+	chan->ops->event_write(ctx, &tid, sizeof(tid));
+}
+
+int lttng_add_tid_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "tid")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "tid";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = tid_get_size;
+	field->record = tid_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_tid_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit TID Context");

drivers/staging/lttng/lttng-context-vpid.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng vPID context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t vpid_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+	size += sizeof(pid_t);
+	return size;
+}
+
+static
+void vpid_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	pid_t vpid;
+
+	/*
+	 * nsproxy can be NULL when scheduled out of exit.
+	 */
+	if (!current->nsproxy)
+		vpid = 0;
+	else
+		vpid = task_tgid_vnr(current);
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(vpid));
+	chan->ops->event_write(ctx, &vpid, sizeof(vpid));
+}
+
+int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "vpid")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "vpid";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = vpid_get_size;
+	field->record = vpid_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_vpid_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit vPID Context");

drivers/staging/lttng/lttng-context-vppid.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng vPPID context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t vppid_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+	size += sizeof(pid_t);
+	return size;
+}
+
+static
+void vppid_record(struct lttng_ctx_field *field,
+		  struct lib_ring_buffer_ctx *ctx,
+		  struct ltt_channel *chan)
+{
+	struct task_struct *parent;
+	pid_t vppid;
+
+	/*
+	 * nsproxy can be NULL when scheduled out of exit.
+	 */
+	rcu_read_lock();
+	parent = rcu_dereference(current->real_parent);
+	if (!parent->nsproxy)
+		vppid = 0;
+	else
+		vppid = task_tgid_vnr(parent);
+	rcu_read_unlock();
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(vppid));
+	chan->ops->event_write(ctx, &vppid, sizeof(vppid));
+}
+
+int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "vppid")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "vppid";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = vppid_get_size;
+	field->record = vppid_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit vPPID Context");

drivers/staging/lttng/lttng-context-vtid.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng vTID context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t vtid_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
+	size += sizeof(pid_t);
+	return size;
+}
+
+static
+void vtid_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	pid_t vtid;
+
+	/*
+	 * nsproxy can be NULL when scheduled out of exit.
+	 */
+	if (!current->nsproxy)
+		vtid = 0;
+	else
+		vtid = task_pid_vnr(current);
+	lib_ring_buffer_align_ctx(ctx, ltt_alignof(vtid));
+	chan->ops->event_write(ctx, &vtid, sizeof(vtid));
+}
+
+int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "vtid")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "vtid";
+	field->event_field.type.atype = atype_integer;
+	field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
+	field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
+	field->event_field.type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.basic.integer.base = 10;
+	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
+	field->get_size = vtid_get_size;
+	field->record = vtid_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_vtid_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit vTID Context");