X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-context-perf-counters.c;h=12839305f5d59acdcc4599587605b98d5bfeb143;hb=218deb69baab57ee2f6728eef18e84697f21197b;hp=7e87be94cfa5a5f7c19d63fe449b8c3ae70d5a76;hpb=77d7fa989f79f3c2cb14d26576cbbb54b0637594;p=lttng-ust.git diff --git a/liblttng-ust/lttng-context-perf-counters.c b/liblttng-ust/lttng-context-perf-counters.c index 7e87be94..12839305 100644 --- a/liblttng-ust/lttng-context-perf-counters.c +++ b/liblttng-ust/lttng-context-perf-counters.c @@ -20,12 +20,15 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ +#define _LGPL_SOURCE #include #include #include #include #include #include +#include +#include #include #include #include @@ -38,6 +41,7 @@ #include #include #include +#include #include "perf_event.h" #include "lttng-tracer-core.h" @@ -70,6 +74,98 @@ 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) { @@ -307,12 +403,12 @@ 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) @@ -366,13 +462,10 @@ static 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) @@ -390,11 +483,11 @@ 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); } @@ -410,11 +503,15 @@ 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); } @@ -471,15 +568,15 @@ 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;