X-Git-Url: http://git.lttng.org/?p=lttng-ust.git;a=blobdiff_plain;f=liblttng-ust%2Flttng-context-perf-counters.c;h=9d57a23345787b7199cca543ed26448e2a633ed7;hp=4816f89b5a4a536e4cc2741e6e5d658379692baf;hb=c0c0989ab70574e09b2f7e8b48c2da6af664a849;hpb=6e9ac4ae894690c95df4566289422c4c05ab472a diff --git a/liblttng-ust/lttng-context-perf-counters.c b/liblttng-ust/lttng-context-perf-counters.c index 4816f89b..9d57a233 100644 --- a/liblttng-ust/lttng-context-perf-counters.c +++ b/liblttng-ust/lttng-context-perf-counters.c @@ -1,23 +1,9 @@ /* - * 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 * - * 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 @@ -27,6 +13,8 @@ #include #include #include +#include +#include #include #include #include @@ -39,6 +27,7 @@ #include #include #include +#include #include "perf_event.h" #include "lttng-tracer-core.h" @@ -71,6 +60,98 @@ struct lttng_perf_counter_field { 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) { @@ -308,12 +389,12 @@ struct lttng_perf_counter_thread_field * * 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) @@ -370,7 +451,7 @@ void perf_counter_get_value(struct lttng_ctx_field *field, 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) @@ -388,11 +469,11 @@ void lttng_destroy_perf_thread_key(void *_key) 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); } @@ -408,11 +489,15 @@ void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field) /* * 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); } @@ -469,15 +554,15 @@ int lttng_add_perf_counter_to_ctx(uint32_t type, 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;