X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=src%2Flib%2Flttng-ust%2Flttng-ust-comm.c;h=e206456f0d98060ea20c2310c4f993c1d6494ece;hb=90d125c709f566f3663bf84677f100134cc618e0;hp=5330e5c2a0c9ed2c6e63170203cc862d80199075;hpb=92d3cba45e0f6ffd5d81bbba7b2d7011b0b18de1;p=lttng-ust.git diff --git a/src/lib/lttng-ust/lttng-ust-comm.c b/src/lib/lttng-ust/lttng-ust-comm.c index 5330e5c2..e206456f 100644 --- a/src/lib/lttng-ust/lttng-ust-comm.c +++ b/src/lib/lttng-ust/lttng-ust-comm.c @@ -1,7 +1,7 @@ /* * SPDX-License-Identifier: LGPL-2.1-only * - * Copyright (C) 2011 David Goulet + * Copyright (C) 2011 EfficiOS Inc. * Copyright (C) 2011 Mathieu Desnoyers */ @@ -38,6 +38,7 @@ #include #include #include +#include #include #include "lib/lttng-ust/futex.h" #include "common/ustcomm.h" @@ -117,6 +118,28 @@ static int lttng_ust_comm_should_quit; */ int lttng_ust_loaded __attribute__((weak)); +/* + * Notes on async-signal-safety of ust lock: a few libc functions are used + * which are not strictly async-signal-safe: + * + * - pthread_setcancelstate + * - pthread_mutex_lock + * - pthread_mutex_unlock + * + * As of glibc 2.35, the implementation of pthread_setcancelstate only + * touches TLS data, and it appears to be safe to use from signal + * handlers. If the libc implementation changes, this will need to be + * revisited, and we may ask glibc to provide an async-signal-safe + * pthread_setcancelstate. + * + * As of glibc 2.35, the implementation of pthread_mutex_lock/unlock + * for fast mutexes only relies on the pthread_mutex_t structure. + * Disabling signals around all uses of this mutex ensures + * signal-safety. If the libc implementation changes and eventually uses + * other global resources, this will need to be revisited and we may + * need to implement our own mutex. + */ + /* * Return 0 on success, -1 if should quit. * The lock is taken in both cases. @@ -125,25 +148,21 @@ int lttng_ust_loaded __attribute__((weak)); int ust_lock(void) { sigset_t sig_all_blocked, orig_mask; - int ret, oldstate; + int ret; - ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); - if (ret) { - ERR("pthread_setcancelstate: %s", strerror(ret)); - } - if (oldstate != PTHREAD_CANCEL_ENABLE) { - ERR("pthread_setcancelstate: unexpected oldstate"); + if (lttng_ust_cancelstate_disable_push()) { + ERR("lttng_ust_cancelstate_disable_push"); } sigfillset(&sig_all_blocked); ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); if (ret) { - ERR("pthread_sigmask: %s", strerror(ret)); + ERR("pthread_sigmask: ret=%d", ret); } if (!URCU_TLS(ust_mutex_nest)++) pthread_mutex_lock(&ust_mutex); ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); if (ret) { - ERR("pthread_sigmask: %s", strerror(ret)); + ERR("pthread_sigmask: ret=%d", ret); } if (lttng_ust_comm_should_quit) { return -1; @@ -161,25 +180,21 @@ int ust_lock(void) void ust_lock_nocheck(void) { sigset_t sig_all_blocked, orig_mask; - int ret, oldstate; + int ret; - ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); - if (ret) { - ERR("pthread_setcancelstate: %s", strerror(ret)); - } - if (oldstate != PTHREAD_CANCEL_ENABLE) { - ERR("pthread_setcancelstate: unexpected oldstate"); + if (lttng_ust_cancelstate_disable_push()) { + ERR("lttng_ust_cancelstate_disable_push"); } sigfillset(&sig_all_blocked); ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); if (ret) { - ERR("pthread_sigmask: %s", strerror(ret)); + ERR("pthread_sigmask: ret=%d", ret); } if (!URCU_TLS(ust_mutex_nest)++) pthread_mutex_lock(&ust_mutex); ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); if (ret) { - ERR("pthread_sigmask: %s", strerror(ret)); + ERR("pthread_sigmask: ret=%d", ret); } } @@ -189,25 +204,21 @@ void ust_lock_nocheck(void) void ust_unlock(void) { sigset_t sig_all_blocked, orig_mask; - int ret, oldstate; + int ret; sigfillset(&sig_all_blocked); ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); if (ret) { - ERR("pthread_sigmask: %s", strerror(ret)); + ERR("pthread_sigmask: ret=%d", ret); } if (!--URCU_TLS(ust_mutex_nest)) pthread_mutex_unlock(&ust_mutex); ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); if (ret) { - ERR("pthread_sigmask: %s", strerror(ret)); + ERR("pthread_sigmask: ret=%d", ret); } - ret = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate); - if (ret) { - ERR("pthread_setcancelstate: %s", strerror(ret)); - } - if (oldstate != PTHREAD_CANCEL_DISABLE) { - ERR("pthread_setcancelstate: unexpected oldstate"); + if (lttng_ust_cancelstate_disable_pop()) { + ERR("lttng_ust_cancelstate_disable_pop"); } } @@ -259,7 +270,7 @@ struct sock_info { int statedump_pending; int initial_statedump_done; /* Keep procname for statedump */ - char procname[LTTNG_UST_ABI_PROCNAME_LEN]; + char procname[LTTNG_UST_CONTEXT_PROCNAME_LEN]; }; /* Socket from app (connect) to session daemon (listen) for communication */ @@ -359,16 +370,26 @@ static char *get_map_shm(struct sock_info *sock_info); /* * Returns the HOME directory path. Caller MUST NOT free(3) the returned * pointer. + * The following env are checked in order of priority: + * 1 - LTTNG_UST_HOME + * 2 - LTTNG_HOME + * 3 - HOME */ static const char *get_lttng_home_dir(void) { const char *val; + val = (const char *) lttng_ust_getenv("LTTNG_UST_HOME"); + if (val != NULL) { + return val; + } + val = (const char *) lttng_ust_getenv("LTTNG_HOME"); if (val != NULL) { return val; } + return (const char *) lttng_ust_getenv("HOME"); } @@ -376,41 +397,41 @@ const char *get_lttng_home_dir(void) * Force a read (imply TLS allocation for dlopen) of TLS variables. */ static -void lttng_nest_count_alloc_tls(void) +void lttng_ust_nest_count_alloc_tls(void) { - asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count))); + __asm__ __volatile__ ("" : : "m" (URCU_TLS(lttng_ust_nest_count))); } static void lttng_ust_mutex_nest_alloc_tls(void) { - asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest))); + __asm__ __volatile__ ("" : : "m" (URCU_TLS(ust_mutex_nest))); } /* * Allocate lttng-ust urcu TLS. */ static -void lttng_lttng_ust_urcu_alloc_tls(void) +void lttng_ust_urcu_alloc_tls(void) { (void) lttng_ust_urcu_read_ongoing(); } -void lttng_ust_alloc_tls(void) +void lttng_ust_common_init_thread(int flags) { - lttng_lttng_ust_urcu_alloc_tls(); + lttng_ust_urcu_alloc_tls(); lttng_ringbuffer_alloc_tls(); - lttng_vtid_alloc_tls(); - lttng_nest_count_alloc_tls(); - lttng_procname_alloc_tls(); + lttng_ust_vtid_init_thread(flags); + lttng_ust_nest_count_alloc_tls(); + lttng_ust_procname_init_thread(flags); lttng_ust_mutex_nest_alloc_tls(); - lttng_ust_perf_counter_alloc_tls(); + lttng_ust_perf_counter_init_thread(flags); lttng_ust_common_alloc_tls(); - lttng_cgroup_ns_alloc_tls(); - lttng_ipc_ns_alloc_tls(); - lttng_net_ns_alloc_tls(); - lttng_time_ns_alloc_tls(); - lttng_uts_ns_alloc_tls(); + lttng_ust_cgroup_ns_init_thread(flags); + lttng_ust_ipc_ns_init_thread(flags); + lttng_ust_net_ns_init_thread(flags); + lttng_ust_time_ns_init_thread(flags); + lttng_ust_uts_ns_init_thread(flags); lttng_ust_ring_buffer_client_discard_alloc_tls(); lttng_ust_ring_buffer_client_discard_rt_alloc_tls(); lttng_ust_ring_buffer_client_overwrite_alloc_tls(); @@ -435,7 +456,9 @@ void lttng_ust_init_thread(void) * ensure those are initialized before a signal handler nesting over * this thread attempts to use them. */ - lttng_ust_alloc_tls(); + lttng_ust_common_init_thread(LTTNG_UST_INIT_THREAD_MASK); + + lttng_ust_urcu_register_thread(); } int lttng_get_notify_socket(void *owner) @@ -482,7 +505,7 @@ int setup_global_apps(void) } global_apps.allowed = 1; - lttng_pthread_getname_np(global_apps.procname, LTTNG_UST_ABI_PROCNAME_LEN); + lttng_pthread_getname_np(global_apps.procname, LTTNG_UST_CONTEXT_PROCNAME_LEN); error: return ret; } @@ -528,7 +551,7 @@ int setup_local_apps(void) goto end; } - lttng_pthread_getname_np(local_apps.procname, LTTNG_UST_ABI_PROCNAME_LEN); + lttng_pthread_getname_np(local_apps.procname, LTTNG_UST_CONTEXT_PROCNAME_LEN); end: return ret; } @@ -620,7 +643,8 @@ void get_allow_blocking(void) } static -int register_to_sessiond(int socket, enum lttng_ust_ctl_socket_type type) +int register_to_sessiond(int socket, enum lttng_ust_ctl_socket_type type, + const char *procname) { return ustcomm_send_reg_msg(socket, type, @@ -629,7 +653,8 @@ int register_to_sessiond(int socket, enum lttng_ust_ctl_socket_type type) lttng_ust_rb_alignof(uint16_t) * CHAR_BIT, lttng_ust_rb_alignof(uint32_t) * CHAR_BIT, lttng_ust_rb_alignof(uint64_t) * CHAR_BIT, - lttng_ust_rb_alignof(unsigned long) * CHAR_BIT); + lttng_ust_rb_alignof(unsigned long) * CHAR_BIT, + procname); } static @@ -1457,8 +1482,7 @@ void cleanup_sock_info(struct sock_info *sock_info, int exiting) } sock_info->root_handle = -1; } - sock_info->registration_done = 0; - sock_info->initial_statedump_done = 0; + /* * wait_shm_mmap, socket and notify socket are used by listener @@ -1470,6 +1494,9 @@ void cleanup_sock_info(struct sock_info *sock_info, int exiting) if (exiting) return; + sock_info->registration_done = 0; + sock_info->initial_statedump_done = 0; + if (sock_info->socket != -1) { ret = ustcomm_close_unix_sock(sock_info->socket); if (ret) { @@ -1567,14 +1594,14 @@ open_write: pid = fork(); URCU_TLS(lttng_ust_nest_count)--; if (pid > 0) { - int status; + int status, wait_ret; /* * Parent: wait for child to return, in which case the * shared memory map will have been created. */ - pid = wait(&status); - if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { + wait_ret = waitpid(pid, &status, 0); + if (wait_ret < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { wait_shm_fd = -1; goto end; } @@ -1742,18 +1769,25 @@ void wait_for_sessiond(struct sock_info *sock_info) DBG("Waiting for %s apps sessiond", sock_info->name); /* Wait for futex wakeup */ - if (uatomic_read((int32_t *) sock_info->wait_shm_mmap)) - goto end_wait; - - while (lttng_ust_futex_async((int32_t *) sock_info->wait_shm_mmap, - FUTEX_WAIT, 0, NULL, NULL, 0)) { + while (!uatomic_read((int32_t *) sock_info->wait_shm_mmap)) { + if (!lttng_ust_futex_async((int32_t *) sock_info->wait_shm_mmap, FUTEX_WAIT, 0, NULL, NULL, 0)) { + /* + * Prior queued wakeups queued by unrelated code + * using the same address can cause futex wait to + * return 0 even through the futex value is still + * 0 (spurious wakeups). Check the value again + * in user-space to validate whether it really + * differs from 0. + */ + continue; + } switch (errno) { - case EWOULDBLOCK: + case EAGAIN: /* Value already changed. */ goto end_wait; case EINTR: /* Retry if interrupted by signal. */ - break; /* Get out of switch. */ + break; /* Get out of switch. Check again. */ case EFAULT: wait_poll_fallback = 1; DBG( @@ -1793,7 +1827,7 @@ void *ust_listener_thread(void *arg) int sock, ret, prev_connect_failed = 0, has_waited = 0, fd; long timeout; - lttng_ust_alloc_tls(); + lttng_ust_common_init_thread(0); /* * If available, add '-ust' to the end of this thread's * process name @@ -1911,7 +1945,8 @@ restart: sock_info->root_handle = ret; } - ret = register_to_sessiond(sock_info->socket, LTTNG_UST_CTL_SOCKET_CMD); + ret = register_to_sessiond(sock_info->socket, LTTNG_UST_CTL_SOCKET_CMD, + sock_info->procname); if (ret < 0) { ERR("Error registering to %s ust cmd socket", sock_info->name); @@ -2004,7 +2039,7 @@ restart: } ret = register_to_sessiond(sock_info->notify_socket, - LTTNG_UST_CTL_SOCKET_NOTIFY); + LTTNG_UST_CTL_SOCKET_NOTIFY, sock_info->procname); if (ret < 0) { ERR("Error registering to %s ust notify socket", sock_info->name); @@ -2100,6 +2135,41 @@ void lttng_ust_libc_wrapper_malloc_ctor(void) { } +/* + * Use a symbol of the previous ABI to detect if liblttng-ust.so.0 is loaded in + * the current process. + */ +#define LTTNG_UST_SONAME_0_SYM "ltt_probe_register" + +static +void lttng_ust_check_soname_0(void) +{ + if (!dlsym(RTLD_DEFAULT, LTTNG_UST_SONAME_0_SYM)) + return; + + CRIT("Incompatible library ABIs detected within the same process. " + "The process is likely linked against different major soname of LTTng-UST which is unsupported. " + "The detection was triggered by lookup of ABI 0 symbol \"%s\" in the Global Symbol Table\n", + LTTNG_UST_SONAME_0_SYM); +} + +/* + * Expose a canary symbol of the previous ABI to ensure we catch uses of a + * liblttng-ust.so.0 dlopen'd after .so.1 has been loaded. Use a different + * symbol than the detection code to ensure we don't detect ourself. + * + * This scheme will only work on systems where the global symbol table has + * priority when resolving the symbols of a dlopened shared object, which is + * the case on Linux but not on FreeBSD. + */ +void init_usterr(void); +void init_usterr(void) +{ + CRIT("Incompatible library ABIs detected within the same process. " + "The process is likely linked against different major soname of LTTng-UST which is unsupported. " + "The detection was triggered by canary symbol \"%s\"\n", __func__); +} + /* * sessiond monitoring thread: monitor presence of global and per-user * sessiond by polling the application common named pipe. @@ -2125,10 +2195,18 @@ void lttng_ust_ctor(void) * to be the dynamic linker mutex) and ust_lock, taken within * the ust lock. */ - lttng_ust_alloc_tls(); + lttng_ust_common_init_thread(0); lttng_ust_loaded = 1; + /* + * Check if we find a symbol of the previous ABI in the current process + * as different ABIs of liblttng-ust can't co-exist in a process. If we + * do so, emit a critical log message which will also abort if the + * LTTNG_UST_ABORT_ON_CRITICAL environment variable is set. + */ + lttng_ust_check_soname_0(); + /* * We need to ensure that the liblttng-ust library is not unloaded to avoid * the unloading of code used by the ust_listener_threads as we can not @@ -2137,7 +2215,7 @@ void lttng_ust_ctor(void) * this library so it never becomes zero, thus never gets unloaded from the * address space of the process. Since we are already running in the * constructor of the LTTNG_UST_LIB_SONAME library, calling dlopen will - * simply increment the refcount and no additionnal work is needed by the + * simply increment the refcount and no additional work is needed by the * dynamic loader as the shared library is already loaded in the address * space. As a safe guard, we use the RTLD_NODELETE flag to prevent * unloading of the UST library if its refcount becomes zero (which should @@ -2147,6 +2225,8 @@ void lttng_ust_ctor(void) handle = dlopen(LTTNG_UST_LIB_SONAME, RTLD_LAZY | RTLD_NODELETE); if (!handle) { ERR("dlopen of liblttng-ust shared library (%s).", LTTNG_UST_LIB_SONAME); + } else { + DBG("dlopened liblttng-ust shared library (%s).", LTTNG_UST_LIB_SONAME); } /* @@ -2429,7 +2509,7 @@ void lttng_ust_before_fork(sigset_t *save_sigset) int ret; /* Allocate lttng-ust TLS. */ - lttng_ust_alloc_tls(); + lttng_ust_common_init_thread(0); if (URCU_TLS(lttng_ust_nest_count)) return; @@ -2472,7 +2552,7 @@ void lttng_ust_after_fork_parent(sigset_t *restore_sigset) return; DBG("process %d", getpid()); lttng_ust_urcu_after_fork_parent(); - /* Release mutexes and reenable signals */ + /* Release mutexes and re-enable signals */ ust_after_fork_common(restore_sigset); } @@ -2499,7 +2579,7 @@ void lttng_ust_after_fork_child(sigset_t *restore_sigset) /* Release urcu mutexes */ lttng_ust_urcu_after_fork_child(); lttng_ust_cleanup(0); - /* Release mutexes and reenable signals */ + /* Release mutexes and re-enable signals */ ust_after_fork_common(restore_sigset); lttng_ust_ctor(); }