/*
- * lttng-context-perf-counters.c
- *
- * LTTng UST performance monitoring counters (perf-counters) integration.
+ * SPDX-License-Identifier: LGPL-2.1-only
*
* Copyright (C) 2009-2014 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
+ * LTTng UST performance monitoring counters (perf-counters) integration.
*/
#define _LGPL_SOURCE
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <lttng/ust-events.h>
#include <urcu/ref.h>
#include <usterr-signal-safe.h>
#include <signal.h>
+#include <urcu/tls-compat.h>
#include "perf_event.h"
#include "lttng-tracer-core.h"
static pthread_key_t perf_counter_key;
+/*
+ * lttng_perf_lock - Protect lttng-ust perf counter data structures
+ *
+ * Nests within the ust_lock, and therefore within the libc dl lock.
+ * Therefore, we need to fixup the TLS before nesting into this lock.
+ * Nests inside RCU bp read-side lock. Protects against concurrent
+ * fork.
+ */
+static pthread_mutex_t ust_perf_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * Cancel state when grabbing the ust_perf_mutex. Saved when locking,
+ * restored on unlock. Protected by ust_perf_mutex.
+ */
+static int ust_perf_saved_cancelstate;
+
+/*
+ * Track whether we are tracing from a signal handler nested on an
+ * application thread.
+ */
+static DEFINE_URCU_TLS(int, ust_perf_mutex_nest);
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+void lttng_ust_fixup_perf_counter_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(ust_perf_mutex_nest)));
+}
+
+void lttng_perf_lock(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret, oldstate;
+
+ ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
+ if (ret) {
+ ERR("pthread_setcancelstate: %s", strerror(ret));
+ }
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (!URCU_TLS(ust_perf_mutex_nest)++) {
+ /*
+ * Ensure the compiler don't move the store after the close()
+ * call in case close() would be marked as leaf.
+ */
+ cmm_barrier();
+ pthread_mutex_lock(&ust_perf_mutex);
+ ust_perf_saved_cancelstate = oldstate;
+ }
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+}
+
+void lttng_perf_unlock(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret, newstate, oldstate;
+ bool restore_cancel = false;
+
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ /*
+ * Ensure the compiler don't move the store before the close()
+ * call, in case close() would be marked as leaf.
+ */
+ cmm_barrier();
+ if (!--URCU_TLS(ust_perf_mutex_nest)) {
+ newstate = ust_perf_saved_cancelstate;
+ restore_cancel = true;
+ pthread_mutex_unlock(&ust_perf_mutex);
+ }
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (restore_cancel) {
+ ret = pthread_setcancelstate(newstate, &oldstate);
+ if (ret) {
+ ERR("pthread_setcancelstate: %s", strerror(ret));
+ }
+ }
+}
+
static
size_t perf_counter_get_size(struct lttng_ctx_field *field, size_t offset)
{
* Note: thread_field->pc can be NULL if setup_perf() fails.
* Also, thread_field->fd can be -1 if open_perf_fd() fails.
*/
- ust_lock_nocheck();
+ lttng_perf_lock();
cds_list_add_rcu(&thread_field->rcu_field_node,
&perf_thread->rcu_field_list);
cds_list_add(&thread_field->thread_field_node,
&perf_field->thread_field_list);
- ust_unlock();
+ lttng_perf_unlock();
skip:
ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
if (ret)
void perf_counter_get_value(struct lttng_ctx_field *field,
struct lttng_ctx_value *value)
{
- uint64_t v;
-
- v = wrapper_perf_counter_read(field);
- value->u.s64 = v;
+ value->u.s64 = wrapper_perf_counter_read(field);
}
-/* Called with UST lock held */
+/* Called with perf lock held */
static
void lttng_destroy_perf_thread_field(
struct lttng_perf_counter_thread_field *thread_field)
struct lttng_perf_counter_thread *perf_thread = _key;
struct lttng_perf_counter_thread_field *pos, *p;
- ust_lock_nocheck();
+ lttng_perf_lock();
cds_list_for_each_entry_safe(pos, p, &perf_thread->rcu_field_list,
rcu_field_node)
lttng_destroy_perf_thread_field(pos);
- ust_unlock();
+ lttng_perf_unlock();
free(perf_thread);
}
/*
* This put is performed when no threads can concurrently
* perform a "get" concurrently, thanks to urcu-bp grace
- * period.
+ * period. Holding the lttng perf lock protects against
+ * concurrent modification of the per-thread thread field
+ * list.
*/
+ lttng_perf_lock();
cds_list_for_each_entry_safe(pos, p, &perf_field->thread_field_list,
thread_field_node)
lttng_destroy_perf_thread_field(pos);
+ lttng_perf_unlock();
free(perf_field);
}
field->event_field.name = name_alloc;
field->event_field.type.atype = atype_integer;
- field->event_field.type.u.basic.integer.size =
+ field->event_field.type.u.integer.size =
sizeof(uint64_t) * CHAR_BIT;
- field->event_field.type.u.basic.integer.alignment =
+ field->event_field.type.u.integer.alignment =
lttng_alignof(uint64_t) * CHAR_BIT;
- field->event_field.type.u.basic.integer.signedness =
+ field->event_field.type.u.integer.signedness =
lttng_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->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 = perf_counter_get_size;
field->record = perf_counter_record;
field->get_value = perf_counter_get_value;
projects / lttng-ust.git / blobdiff