From ae14f8220190e23cc9d9ec6023c1813a8fb2ad32 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 23 Feb 2021 15:48:59 -0500 Subject: [PATCH] Remove backward compatibility for liburcu-bp Now that the soname is bumped, there is no backward compatibility to keep for tracepoint call sites using liburcu-bp for synchronization, so this compatibility code can be removed. Signed-off-by: Mathieu Desnoyers Change-Id: I35d84fa1ffdb033c094b1a6989cc1c3bc29ce7f8 --- include/lttng/tracepoint.h | 23 +----- liblttng-ust/lttng-ust-comm.c | 12 +--- liblttng-ust/tracepoint.c | 132 +--------------------------------- 3 files changed, 7 insertions(+), 160 deletions(-) diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h index 51eafdeb..c4668eab 100644 --- a/include/lttng/tracepoint.h +++ b/include/lttng/tracepoint.h @@ -271,7 +271,6 @@ struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr * control and check if the destructors should be executed. */ struct lttng_ust_tracepoint_destructors_syms { - int *old_tracepoint_disable_destructors; void (*tracepoint_disable_destructors)(void); int (*tracepoint_get_destructors_state)(void); }; @@ -293,7 +292,6 @@ static inline void tracepoint_disable_destructors(void) if (tracepoint_dlopen_ptr->liblttngust_handle && tracepoint_destructors_syms_ptr->tracepoint_disable_destructors) tracepoint_destructors_syms_ptr->tracepoint_disable_destructors(); - *tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors = 1; } #ifndef _LGPL_SOURCE @@ -384,19 +382,6 @@ __tracepoints__destroy(void) */ return; } - /* - * Lookup if destructors must be executed using the old method. - */ - if (tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors - && *tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors) { - /* - * The old_tracepoint_disable_destructors symbol was found with - * dlsym but its value is 1 meaning that destructors must not - * be executed. - */ - return; - } - ret = dlclose(tracepoint_dlopen_ptr->liblttngust_handle); if (ret) { fprintf(stderr, "Error (%d) in dlclose\n", ret); @@ -479,15 +464,11 @@ __tracepoints__ptrs_init(void) tracepoint_dlopen_ptr->tracepoint_register_lib = URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *, int), dlsym(tracepoint_dlopen_ptr->liblttngust_handle, - "tracepoint_register_lib2")); + "tracepoint_register_lib")); tracepoint_dlopen_ptr->tracepoint_unregister_lib = URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *), dlsym(tracepoint_dlopen_ptr->liblttngust_handle, - "tracepoint_unregister_lib2")); - tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors = - URCU_FORCE_CAST(int *, - dlsym(tracepoint_dlopen_ptr->liblttngust_handle, - "__tracepoints__disable_destructors")); + "tracepoint_unregister_lib")); tracepoint_destructors_syms_ptr->tracepoint_disable_destructors = URCU_FORCE_CAST(void (*)(void), dlsym(tracepoint_dlopen_ptr->liblttngust_handle, diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c index 8d90e2c3..81dfbc9a 100644 --- a/liblttng-ust/lttng-ust-comm.c +++ b/liblttng-ust/lttng-ust-comm.c @@ -430,17 +430,17 @@ void lttng_fixup_ust_mutex_nest_tls(void) } /* - * Fixup urcu bp TLS. + * Fixup lttng-ust urcu TLS. */ static -void lttng_fixup_urcu_bp_tls(void) +void lttng_fixup_lttng_ust_urcu_tls(void) { (void) lttng_ust_urcu_read_ongoing(); } void lttng_ust_fixup_tls(void) { - lttng_fixup_urcu_bp_tls(); + lttng_fixup_lttng_ust_urcu_tls(); lttng_fixup_ringbuffer_tls(); lttng_fixup_vtid_tls(); lttng_fixup_nest_count_tls(); @@ -2402,8 +2402,6 @@ void ust_before_fork(sigset_t *save_sigset) ust_lock_nocheck(); lttng_ust_urcu_before_fork(); - if (lttng_ust_liburcu_bp_before_fork) - lttng_ust_liburcu_bp_before_fork(); lttng_ust_lock_fd_tracker(); lttng_perf_lock(); } @@ -2432,8 +2430,6 @@ void ust_after_fork_parent(sigset_t *restore_sigset) return; DBG("process %d", getpid()); lttng_ust_urcu_after_fork_parent(); - if (lttng_ust_liburcu_bp_after_fork_parent) - lttng_ust_liburcu_bp_after_fork_parent(); /* Release mutexes and reenable signals */ ust_after_fork_common(restore_sigset); } @@ -2460,8 +2456,6 @@ void ust_after_fork_child(sigset_t *restore_sigset) DBG("process %d", getpid()); /* Release urcu mutexes */ lttng_ust_urcu_after_fork_child(); - if (lttng_ust_liburcu_bp_after_fork_child) - lttng_ust_liburcu_bp_after_fork_child(); lttng_ust_cleanup(0); /* Release mutexes and reenable signals */ ust_after_fork_common(restore_sigset); diff --git a/liblttng-ust/tracepoint.c b/liblttng-ust/tracepoint.c index ce7dbbb2..b556af89 100644 --- a/liblttng-ust/tracepoint.c +++ b/liblttng-ust/tracepoint.c @@ -60,15 +60,6 @@ static int initialized; */ static int tracepoint_destructors_state = 1; -/* - * Expose the now deprecated symbol __tracepoints__disable_destructors for - * backward compatibility of applications built against old versions of - * lttng-ust. We need to keep __tracepoints__disable_destructors up to date - * within the new destructor disabling API because old applications read this - * symbol directly. - */ -int __tracepoints__disable_destructors __attribute__((weak)); - static void (*new_tracepoint_cb)(struct lttng_ust_tracepoint *); /* @@ -151,86 +142,6 @@ struct callsite_entry { bool tp_entry_callsite_ref; /* Has a tp_entry took a ref on this callsite */ }; -static int tracepoint_v1_api_used; -static void (*lttng_ust_liburcu_bp_synchronize_rcu)(void); -static void (*lttng_ust_liburcu_bp_rcu_read_lock)(void); -static void (*lttng_ust_liburcu_bp_rcu_read_unlock)(void); -void (*lttng_ust_liburcu_bp_before_fork)(void); -void (*lttng_ust_liburcu_bp_after_fork_parent)(void); -void (*lttng_ust_liburcu_bp_after_fork_child)(void); - -static bool lttng_ust_tracepoint_v1_used(void) -{ - return uatomic_read(&tracepoint_v1_api_used); -} - -static void lttng_ust_tracepoint_set_v1_used(void) -{ - if (!lttng_ust_tracepoint_v1_used()) { - /* - * Perform dlsym here rather than lazily on first use to - * eliminate nesting of dynamic loader lock (used within - * dlsym) inside the ust lock. - */ - if (!lttng_ust_liburcu_bp_synchronize_rcu) { - lttng_ust_liburcu_bp_synchronize_rcu = URCU_FORCE_CAST(void (*)(void), - dlsym(RTLD_DEFAULT, "synchronize_rcu_bp")); - /* - * Allow legacy applications compiled without - * _LGPL_SOURCE to use v1 API. Those are not - * required to be linked against liburcu-bp, - * so in those situations the liburcu-bp symbols - * are not present in the global symbol table, - * and we do not need to call urcu-bp - * synchronize. - * - * However, nothing prevents a _LGPL_SOURCE - * instrumented library loaded afterwards to - * require liburcu-bp, so we need to check again - * in that situation. - */ - if (!lttng_ust_liburcu_bp_synchronize_rcu) - return; - } - if (!lttng_ust_liburcu_bp_before_fork) { - lttng_ust_liburcu_bp_before_fork = URCU_FORCE_CAST(void (*)(void), - dlsym(RTLD_DEFAULT, "rcu_bp_before_fork")); - if (!lttng_ust_liburcu_bp_before_fork) - abort(); - } - if (!lttng_ust_liburcu_bp_after_fork_parent) { - lttng_ust_liburcu_bp_after_fork_parent = URCU_FORCE_CAST(void (*)(void), - dlsym(RTLD_DEFAULT, "rcu_bp_after_fork_parent")); - if (!lttng_ust_liburcu_bp_after_fork_parent) - abort(); - } - if (!lttng_ust_liburcu_bp_after_fork_child) { - lttng_ust_liburcu_bp_after_fork_child = URCU_FORCE_CAST(void (*)(void), - dlsym(RTLD_DEFAULT, "rcu_bp_after_fork_child")); - if (!lttng_ust_liburcu_bp_after_fork_child) - abort(); - } - if (!lttng_ust_liburcu_bp_rcu_read_lock) { - lttng_ust_liburcu_bp_rcu_read_lock = URCU_FORCE_CAST(void (*)(void), - dlsym(RTLD_DEFAULT, "rcu_read_lock_bp")); - if (!lttng_ust_liburcu_bp_rcu_read_lock) - abort(); - } - if (!lttng_ust_liburcu_bp_rcu_read_unlock) { - lttng_ust_liburcu_bp_rcu_read_unlock = URCU_FORCE_CAST(void (*)(void), - dlsym(RTLD_DEFAULT, "rcu_read_unlock_bp")); - if (!lttng_ust_liburcu_bp_rcu_read_unlock) - abort(); - } - - /* Fixup URCU bp TLS. */ - lttng_ust_liburcu_bp_rcu_read_lock(); - lttng_ust_liburcu_bp_rcu_read_unlock(); - - uatomic_set(&tracepoint_v1_api_used, 1); - } -} - /* coverity[+alloc] */ static void *allocate_probes(int count) { @@ -960,7 +871,7 @@ static void new_tracepoints(struct lttng_ust_tracepoint * const *start, * against recent liblttng-ust headers require a recent liblttng-ust * runtime for those tracepoints to be taken into account. */ -int tracepoint_register_lib2(struct lttng_ust_tracepoint * const *tracepoints_start, +int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start, int tracepoints_count) { struct tracepoint_lib *pl, *iter; @@ -1009,15 +920,7 @@ lib_added: return 0; } -/* Exposed for backward compatibility with old instrumented applications. */ -int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start, - int tracepoints_count) -{ - lttng_ust_tracepoint_set_v1_used(); - return tracepoint_register_lib2(tracepoints_start, tracepoints_count); -} - -int tracepoint_unregister_lib2(struct lttng_ust_tracepoint * const *tracepoints_start) +int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start) { struct tracepoint_lib *lib; @@ -1043,13 +946,6 @@ int tracepoint_unregister_lib2(struct lttng_ust_tracepoint * const *tracepoints_ return 0; } -/* Exposed for backward compatibility with old instrumented applications. */ -int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start) -{ - lttng_ust_tracepoint_set_v1_used(); - return tracepoint_unregister_lib2(tracepoints_start); -} - /* * Report in debug message whether the compiler correctly supports weak * hidden symbols. This test checks that the address associated with two @@ -1135,28 +1031,4 @@ int tp_get_destructors_state(void) void lttng_ust_synchronize_trace(void) { lttng_ust_urcu_synchronize_rcu(); - /* - * For legacy tracepoint instrumentation, also wait for urcu-bp - * grace period. - */ - if (lttng_ust_liburcu_bp_synchronize_rcu) - lttng_ust_liburcu_bp_synchronize_rcu(); -} - -/* - * Create the wrapper symbols for legacy v1 API. - */ -void tp_rcu_read_lock_bp(void) -{ - lttng_ust_urcu_read_lock(); -} - -void tp_rcu_read_unlock_bp(void) -{ - lttng_ust_urcu_read_unlock(); -} - -void *tp_rcu_dereference_sym_bp(void *p) -{ - return lttng_ust_rcu_dereference(p); } -- 2.34.1