/*
* lttng-context.c
*
* LTTng UST trace/channel/event context management.
*
* Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; only
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <lttng/ust-events.h>
#include <lttng/ust-tracer.h>
#include <lttng/ust-context-provider.h>
#include <urcu-pointer.h>
#include <usterr-signal-safe.h>
#include <helper.h>
#include <string.h>
#include <assert.h>
/*
* The filter implementation requires that two consecutive "get" for the
* same context performed by the same thread return the same result.
*/
int lttng_find_context(struct lttng_ctx *ctx, const char *name)
{
unsigned int i;
const char *subname;
if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
subname = name + strlen("$ctx.");
} else {
subname = name;
}
for (i = 0; i < ctx->nr_fields; i++) {
/* Skip allocated (but non-initialized) contexts */
if (!ctx->fields[i].event_field.name)
continue;
if (!strcmp(ctx->fields[i].event_field.name, subname))
return 1;
}
return 0;
}
int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
{
unsigned int i;
const char *subname;
if (!ctx)
return -1;
if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
subname = name + strlen("$ctx.");
} else {
subname = name;
}
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, subname))
return i;
}
return -1;
}
static int lttng_find_context_provider(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 (!strncmp(ctx->fields[i].event_field.name, name,
strlen(name)))
return 1;
}
return 0;
}
/*
* 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 = zmalloc(sizeof(struct lttng_ctx));
if (!*ctx_p)
return NULL;
(*ctx_p)->largest_align = 1;
}
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 = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
if (!new_fields)
return NULL;
if (ctx->fields)
memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
free(ctx->fields);
ctx->fields = new_fields;
}
field = &ctx->fields[ctx->nr_fields];
ctx->nr_fields++;
return field;
}
int lttng_context_add_rcu(struct lttng_ctx **ctx_p,
const struct lttng_ctx_field *f)
{
struct lttng_ctx *old_ctx = *ctx_p, *new_ctx = NULL;
struct lttng_ctx_field *new_fields = NULL;
struct lttng_ctx_field *nf;
if (old_ctx) {
new_ctx = zmalloc(sizeof(struct lttng_ctx));
if (!new_ctx)
return -ENOMEM;
*new_ctx = *old_ctx;
new_fields = zmalloc(new_ctx->allocated_fields
* sizeof(struct lttng_ctx_field));
if (!new_fields) {
free(new_ctx);
return -ENOMEM;
}
memcpy(new_fields, old_ctx->fields,
sizeof(*old_ctx->fields) * old_ctx->nr_fields);
new_ctx->fields = new_fields;
}
nf = lttng_append_context(&new_ctx);
if (!nf) {
free(new_fields);
free(new_ctx);
return -ENOMEM;
}
*nf = *f;
lttng_context_update(new_ctx);
rcu_assign_pointer(*ctx_p, new_ctx);
synchronize_trace();
if (old_ctx) {
free(old_ctx->fields);
free(old_ctx);
}
return 0;
}
/*
* lttng_context_update() should be called at least once between context
* modification and trace start.
*/
void lttng_context_update(struct lttng_ctx *ctx)
{
int i;
size_t largest_align = 8; /* in bits */
for (i = 0; i < ctx->nr_fields; i++) {
struct lttng_type *type;
size_t field_align = 8;
type = &ctx->fields[i].event_field.type;
switch (type->atype) {
case atype_integer:
field_align = type->u.basic.integer.alignment;
break;
case atype_array:
{
struct lttng_basic_type *btype;
btype = &type->u.array.elem_type;
switch (btype->atype) {
case atype_integer:
field_align = btype->u.basic.integer.alignment;
break;
case atype_string:
break;
case atype_array:
case atype_sequence:
default:
WARN_ON_ONCE(1);
break;
}
break;
}
case atype_sequence:
{
struct lttng_basic_type *btype;
btype = &type->u.sequence.length_type;
switch (btype->atype) {
case atype_integer:
field_align = btype->u.basic.integer.alignment;
break;
case atype_string:
case atype_array:
case atype_sequence:
default:
WARN_ON_ONCE(1);
break;
}
btype = &type->u.sequence.elem_type;
switch (btype->atype) {
case atype_integer:
field_align = max_t(size_t,
field_align,
btype->u.basic.integer.alignment);
break;
case atype_string:
break;
case atype_array:
case atype_sequence:
default:
WARN_ON_ONCE(1);
break;
}
break;
}
case atype_string:
break;
case atype_dynamic:
break;
case atype_enum:
default:
WARN_ON_ONCE(1);
break;
}
largest_align = max_t(size_t, largest_align, field_align);
}
ctx->largest_align = largest_align >> 3; /* bits to bytes */
}
/*
* 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--;
assert(&ctx->fields[ctx->nr_fields] == field);
assert(field->field_name == NULL);
memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_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]);
free(ctx->fields[i].field_name);
}
free(ctx->fields);
free(ctx);
}
/*
* Can be safely performed concurrently with tracing using the struct
* lttng_ctx. Using RCU update. Needs to match RCU read-side handling of
* contexts.
*
* This does not allow adding, removing, or changing typing of the
* contexts, since this needs to stay invariant for metadata. However,
* it allows updating the handlers associated with all contexts matching
* a provider (by name) while tracing is using it, in a way that ensures
* a single RCU read-side critical section see either all old, or all
* new handlers.
*/
int lttng_ust_context_set_provider_rcu(struct lttng_ctx **_ctx,
const char *name,
size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
void (*record)(struct lttng_ctx_field *field,
struct lttng_ust_lib_ring_buffer_ctx *ctx,
struct lttng_channel *chan),
void (*get_value)(struct lttng_ctx_field *field,
struct lttng_ctx_value *value))
{
int i, ret;
struct lttng_ctx *ctx = *_ctx, *new_ctx;
struct lttng_ctx_field *new_fields;
if (!ctx || !lttng_find_context_provider(ctx, name))
return 0;
/*
* We have at least one instance of context for the provider.
*/
new_ctx = zmalloc(sizeof(*new_ctx));
if (!new_ctx)
return -ENOMEM;
*new_ctx = *ctx;
new_fields = zmalloc(sizeof(*new_fields) * ctx->allocated_fields);
if (!new_fields) {
ret = -ENOMEM;
goto field_error;
}
memcpy(new_fields, ctx->fields,
sizeof(*new_fields) * ctx->allocated_fields);
for (i = 0; i < ctx->nr_fields; i++) {
if (strncmp(new_fields[i].event_field.name,
name, strlen(name)) != 0)
continue;
new_fields[i].get_size = get_size;
new_fields[i].record = record;
new_fields[i].get_value = get_value;
}
new_ctx->fields = new_fields;
rcu_assign_pointer(*_ctx, new_ctx);
synchronize_trace();
free(ctx->fields);
free(ctx);
return 0;
field_error:
free(new_ctx);
return ret;
}
int lttng_session_context_init(struct lttng_ctx **ctx)
{
int ret;
ret = lttng_add_pthread_id_to_ctx(ctx);
if (ret) {
WARN("Cannot add context lttng_add_pthread_id_to_ctx");
goto error;
}
ret = lttng_add_vtid_to_ctx(ctx);
if (ret) {
WARN("Cannot add context lttng_add_vtid_to_ctx");
goto error;
}
ret = lttng_add_vpid_to_ctx(ctx);
if (ret) {
WARN("Cannot add context lttng_add_vpid_to_ctx");
goto error;
}
ret = lttng_add_procname_to_ctx(ctx);
if (ret) {
WARN("Cannot add context lttng_add_procname_to_ctx");
goto error;
}
ret = lttng_add_cpu_id_to_ctx(ctx);
if (ret) {
WARN("Cannot add context lttng_add_cpu_id_to_ctx");
goto error;
}
lttng_context_update(*ctx);
return 0;
error:
lttng_destroy_context(*ctx);
return ret;
}
/* For backward compatibility. Leave those exported symbols in place. */
struct lttng_ctx *lttng_static_ctx;
void lttng_context_init(void)
{
}
void lttng_context_exit(void)
{
}