/*
- * (C) Copyright 2009-2011 -
- * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * lttng-context-vtid.c
*
* LTTng UST vtid context.
*
- * Dual LGPL v2.1/GPL v2 license.
+ * Copyright (C) 2009-2012 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
*/
+#define _LGPL_SOURCE
+#include <stddef.h>
#include <sys/types.h>
#include <unistd.h>
#include <lttng/ust-events.h>
#include <lttng/ust-tracer.h>
#include <lttng/ringbuffer-config.h>
#include <lttng/ust-tid.h>
+#include <urcu/tls-compat.h>
+#include "lttng-tracer-core.h"
/*
* We cache the result to ensure we don't trigger a system call for
* each event.
*/
-static __thread pid_t cached_vtid;
+static DEFINE_URCU_TLS(pid_t, cached_vtid);
/*
* Upon fork or clone, the TID assigned to our thread is not the same as
*/
void lttng_context_vtid_reset(void)
{
- cached_vtid = 0;
+ CMM_STORE_SHARED(URCU_TLS(cached_vtid), 0);
}
static
-size_t vtid_get_size(size_t offset)
+size_t vtid_get_size(struct lttng_ctx_field *field, size_t offset)
{
size_t size = 0;
return size;
}
+static inline
+pid_t wrapper_getvtid(void)
+{
+ pid_t vtid;
+
+ vtid = CMM_LOAD_SHARED(URCU_TLS(cached_vtid));
+ if (caa_unlikely(!vtid)) {
+ vtid = lttng_gettid();
+ CMM_STORE_SHARED(URCU_TLS(cached_vtid), vtid);
+ }
+ return vtid;
+}
+
static
void vtid_record(struct lttng_ctx_field *field,
struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct ltt_channel *chan)
+ struct lttng_channel *chan)
+{
+ pid_t vtid = wrapper_getvtid();
+
+ lib_ring_buffer_align_ctx(ctx, lttng_alignof(vtid));
+ chan->ops->event_write(ctx, &vtid, sizeof(vtid));
+}
+
+static
+void vtid_get_value(struct lttng_ctx_field *field,
+ struct lttng_ctx_value *value)
{
- if (caa_unlikely(!cached_vtid))
- cached_vtid = gettid();
- lib_ring_buffer_align_ctx(ctx, lttng_alignof(cached_vtid));
- chan->ops->event_write(ctx, &cached_vtid, sizeof(cached_vtid));
+ value->u.s64 = wrapper_getvtid();
}
int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
}
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 = lttng_alignof(pid_t) * CHAR_BIT;
- field->event_field.type.u.basic.integer.signedness = lttng_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->event_field.type.u.integer.size = sizeof(pid_t) * CHAR_BIT;
+ field->event_field.type.u.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
+ field->event_field.type.u.integer.signedness = lttng_is_signed_type(pid_t);
+ field->event_field.type.u.integer.reverse_byte_order = 0;
+ field->event_field.type.u.integer.base = 10;
+ field->event_field.type.u.integer.encoding = lttng_encode_none;
field->get_size = vtid_get_size;
field->record = vtid_record;
+ field->get_value = vtid_get_value;
+ lttng_context_update(*ctx);
return 0;
}
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+void lttng_fixup_vtid_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(cached_vtid)));
+}