/*
- * (C) Copyright 2009-2011 -
- * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * lttng-context-procname.c
*
* LTTng UST procname 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
*/
-#include <sys/prctl.h>
#include <lttng/ust-events.h>
#include <lttng/ust-tracer.h>
#include <lttng/ringbuffer-config.h>
+#include <urcu/tls-compat.h>
#include <assert.h>
-
-#define PROCNAME_LEN 17 /* includes \0 */
+#include "compat.h"
/*
* We cache the result to ensure we don't trigger a system call for
* each event.
* Upon exec, procname changes, but exec takes care of throwing away
* this cached version.
+ * The procname can also change by calling prctl(). The procname should
+ * be set for a thread before the first event is logged within this
+ * thread.
*/
-static char cached_procname[17];
+typedef char procname_array[17];
+static DEFINE_URCU_TLS(procname_array, cached_procname);
static inline
char *wrapper_getprocname(void)
{
- int ret;
-
- if (caa_unlikely(!cached_procname[0])) {
- ret = prctl(PR_GET_NAME, (unsigned long) cached_procname,
- 0, 0, 0);
- assert(!ret);
+ if (caa_unlikely(!URCU_TLS(cached_procname)[0])) {
+ lttng_ust_getprocname(URCU_TLS(cached_procname));
+ URCU_TLS(cached_procname)[LTTNG_UST_PROCNAME_LEN - 1] = '\0';
}
- return cached_procname;
+ return URCU_TLS(cached_procname);
}
void lttng_context_procname_reset(void)
{
- cached_procname[0] = '\0';
+ URCU_TLS(cached_procname)[0] = '\0';
}
static
-size_t procname_get_size(size_t offset)
+size_t procname_get_size(struct lttng_ctx_field *field, size_t offset)
{
size_t size = 0;
- size += PROCNAME_LEN;
+ size += LTTNG_UST_PROCNAME_LEN;
return size;
}
static
void procname_record(struct lttng_ctx_field *field,
struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct ltt_channel *chan)
+ struct lttng_channel *chan)
{
char *procname;
procname = wrapper_getprocname();
- chan->ops->event_write(ctx, procname, PROCNAME_LEN);
+ chan->ops->event_write(ctx, procname, LTTNG_UST_PROCNAME_LEN);
+}
+
+static
+void procname_get_value(struct lttng_ctx_field *field,
+ struct lttng_ctx_value *value)
+{
+ char *procname;
+
+ procname = wrapper_getprocname();
+ value->u.str = procname;
}
int lttng_add_procname_to_ctx(struct lttng_ctx **ctx)
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 = PROCNAME_LEN;
+ field->event_field.type.u.array.length = LTTNG_UST_PROCNAME_LEN;
field->get_size = procname_get_size;
field->record = procname_record;
+ field->get_value = procname_get_value;
+ lttng_context_update(*ctx);
return 0;
}
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+void lttng_fixup_procname_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(cached_procname)[0]));
+}