X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-comm.c;h=2c787f75b88ae3f32b27582bcaeb3607b52d4083;hb=e38c8fc1be27964f9a87afca4db5ae164fe09371;hp=44e8bab4c24ca4aa2a77b72727288c9b24c8e67d;hpb=e6ea14c54c9b1dd79428e61e0343d8a34d87b5a8;p=lttng-ust.git diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c index 44e8bab4..2c787f75 100644 --- a/liblttng-ust/lttng-ust-comm.c +++ b/liblttng-ust/lttng-ust-comm.c @@ -46,6 +46,7 @@ #include #include "tracepoint-internal.h" #include "ltt-tracer-core.h" +#include "../libringbuffer/tlsfixup.h" /* * Has lttng ust comm constructor been called ? @@ -77,6 +78,12 @@ static sem_t constructor_wait; */ static int sem_count = { 2 }; +/* + * Counting nesting within lttng-ust. Used to ensure that calling fork() + * from liblttng-ust does not execute the pre/post fork handlers. + */ +static int __thread lttng_ust_nest_count; + /* * Info about socket and associated listener thread. */ @@ -129,6 +136,15 @@ extern void ltt_ring_buffer_client_overwrite_exit(void); extern void ltt_ring_buffer_client_discard_exit(void); extern void ltt_ring_buffer_metadata_client_exit(void); +/* + * Force a read (imply TLS fixup for dlopen) of TLS variables. + */ +static +void lttng_fixup_nest_count_tls(void) +{ + asm volatile ("" : : "m" (lttng_ust_nest_count)); +} + static int setup_local_apps(void) { @@ -324,14 +340,20 @@ end: || lum->cmd == LTTNG_UST_CHANNEL || lum->cmd == LTTNG_UST_METADATA) && lur.ret_code == USTCOMM_OK) { + int sendret = 0; + /* we also need to send the file descriptors. */ ret = ustcomm_send_fds_unix_sock(sock, &shm_fd, &shm_fd, 1, sizeof(int)); if (ret < 0) { perror("send shm_fd"); - goto error; + sendret = ret; } + /* + * The sessiond expects 2 file descriptors, even upon + * error. + */ ret = ustcomm_send_fds_unix_sock(sock, &wait_fd, &wait_fd, 1, sizeof(int)); @@ -339,6 +361,10 @@ end: perror("send wait_fd"); goto error; } + if (sendret) { + ret = sendret; + goto error; + } } /* * We still have the memory map reference, and the fds have been @@ -395,7 +421,7 @@ void cleanup_sock_info(struct sock_info *sock_info, int exiting) int ret; if (sock_info->socket != -1) { - ret = close(sock_info->socket); + ret = ustcomm_close_unix_sock(sock_info->socket); if (ret) { ERR("Error closing apps socket"); } @@ -458,7 +484,9 @@ int get_wait_shm(struct sock_info *sock_info, size_t mmap_size) * If the open failed because the file did not exist, try * creating it ourself. */ + lttng_ust_nest_count++; pid = fork(); + lttng_ust_nest_count--; if (pid > 0) { int status; @@ -675,7 +703,7 @@ restart: } if (sock_info->socket != -1) { - ret = close(sock_info->socket); + ret = ustcomm_close_unix_sock(sock_info->socket); if (ret) { ERR("Error closing %s apps socket", sock_info->name); } @@ -826,12 +854,23 @@ int get_timeout(struct timespec *constructor_timeout) void __attribute__((constructor)) lttng_ust_init(void) { struct timespec constructor_timeout; + sigset_t sig_all_blocked, orig_parent_mask; int timeout_mode; int ret; if (uatomic_xchg(&initialized, 1) == 1) return; + /* + * Fixup interdependency between TLS fixup mutex (which happens + * to be the dynamic linker mutex) and ust_lock, taken within + * the ust lock. + */ + lttng_fixup_event_tls(); + lttng_fixup_ringbuffer_tls(); + lttng_fixup_vtid_tls(); + lttng_fixup_nest_count_tls(); + /* * We want precise control over the order in which we construct * our sub-libraries vs starting to receive commands from @@ -853,16 +892,39 @@ void __attribute__((constructor)) lttng_ust_init(void) if (ret) { ERR("Error setting up to local apps"); } - ret = pthread_create(&local_apps.ust_listener, NULL, - ust_listener_thread, &local_apps); + /* A new thread created by pthread_create inherits the signal mask + * from the parent. To avoid any signal being received by the + * listener thread, we block all signals temporarily in the parent, + * while we create the listener thread. + */ + sigfillset(&sig_all_blocked); + ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask); + if (ret) { + ERR("pthread_sigmask: %s", strerror(ret)); + } + + ret = pthread_create(&global_apps.ust_listener, NULL, + ust_listener_thread, &global_apps); + if (ret) { + ERR("pthread_create global: %s", strerror(ret)); + } if (local_apps.allowed) { - ret = pthread_create(&global_apps.ust_listener, NULL, - ust_listener_thread, &global_apps); + ret = pthread_create(&local_apps.ust_listener, NULL, + ust_listener_thread, &local_apps); + if (ret) { + ERR("pthread_create local: %s", strerror(ret)); + } } else { handle_register_done(&local_apps); } + /* Restore original signal mask in parent */ + ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL); + if (ret) { + ERR("pthread_sigmask: %s", strerror(ret)); + } + switch (timeout_mode) { case 1: /* timeout wait */ do { @@ -936,12 +998,14 @@ void __attribute__((destructor)) lttng_ust_exit(void) /* cancel threads */ ret = pthread_cancel(global_apps.ust_listener); if (ret) { - ERR("Error cancelling global ust listener thread"); + ERR("Error cancelling global ust listener thread: %s", + strerror(ret)); } if (local_apps.allowed) { ret = pthread_cancel(local_apps.ust_listener); if (ret) { - ERR("Error cancelling local ust listener thread"); + ERR("Error cancelling local ust listener thread: %s", + strerror(ret)); } } /* @@ -973,6 +1037,8 @@ void ust_before_fork(sigset_t *save_sigset) sigset_t all_sigs; int ret; + if (lttng_ust_nest_count) + return; /* Disable signals */ sigfillset(&all_sigs); ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset); @@ -998,6 +1064,8 @@ static void ust_after_fork_common(sigset_t *restore_sigset) void ust_after_fork_parent(sigset_t *restore_sigset) { + if (lttng_ust_nest_count) + return; DBG("process %d", getpid()); rcu_bp_after_fork_parent(); /* Release mutexes and reenable signals */ @@ -1015,6 +1083,8 @@ void ust_after_fork_parent(sigset_t *restore_sigset) */ void ust_after_fork_child(sigset_t *restore_sigset) { + if (lttng_ust_nest_count) + return; DBG("process %d", getpid()); /* Release urcu mutexes */ rcu_bp_after_fork_child();