X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-comm.c;h=b90df8610edb6cee07e0bef8ac4ec82cb787b5a2;hb=f645cfa794fc481dff6cb30ea56e93f825b3d423;hp=d0641c5c6e510b01d0538d9c36b07c5c430644c6;hpb=48621a4272bdeb1e8fced511ca6bf3c4c2240c15;p=lttng-ust.git diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c index d0641c5c..b90df861 100644 --- a/liblttng-ust/lttng-ust-comm.c +++ b/liblttng-ust/lttng-ust-comm.c @@ -22,6 +22,7 @@ #define _LGPL_SOURCE #include #include +#include #include #include #include @@ -45,7 +46,7 @@ #include #include "tracepoint-internal.h" #include "ltt-tracer-core.h" -#include "compat.h" +#include "../libringbuffer/tlsfixup.h" /* * Has lttng ust comm constructor been called ? @@ -159,6 +160,7 @@ static int register_app_to_sessiond(int socket) { ssize_t ret; + int prctl_ret; struct { uint32_t major; uint32_t minor; @@ -177,7 +179,11 @@ int register_app_to_sessiond(int socket) reg_msg.uid = getuid(); reg_msg.gid = getgid(); reg_msg.bits_per_long = CAA_BITS_PER_LONG; - lttng_ust_getprocname(reg_msg.name); + prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0); + if (prctl_ret) { + ERR("Error executing prctl"); + return -errno; + } ret = ustcomm_send_unix_sock(socket, ®_msg, sizeof(reg_msg)); if (ret >= 0 && ret != sizeof(reg_msg)) @@ -284,28 +290,30 @@ end: //lur.ret_code = USTCOMM_SESSION_FAIL; lur.ret_code = ret; } - switch (lum->cmd) { - case LTTNG_UST_STREAM: - /* - * Special-case reply to send stream info. - * Use lum.u output. - */ - lur.u.stream.memory_map_size = *args.stream.memory_map_size; - shm_fd = *args.stream.shm_fd; - wait_fd = *args.stream.wait_fd; - break; - case LTTNG_UST_METADATA: - case LTTNG_UST_CHANNEL: - lur.u.channel.memory_map_size = *args.channel.memory_map_size; - shm_fd = *args.channel.shm_fd; - wait_fd = *args.channel.wait_fd; - break; - case LTTNG_UST_TRACER_VERSION: - lur.u.version = lum->u.version; - break; - case LTTNG_UST_TRACEPOINT_LIST_GET: - memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint)); - break; + if (ret >= 0) { + switch (lum->cmd) { + case LTTNG_UST_STREAM: + /* + * Special-case reply to send stream info. + * Use lum.u output. + */ + lur.u.stream.memory_map_size = *args.stream.memory_map_size; + shm_fd = *args.stream.shm_fd; + wait_fd = *args.stream.wait_fd; + break; + case LTTNG_UST_METADATA: + case LTTNG_UST_CHANNEL: + lur.u.channel.memory_map_size = *args.channel.memory_map_size; + shm_fd = *args.channel.shm_fd; + wait_fd = *args.channel.wait_fd; + break; + case LTTNG_UST_TRACER_VERSION: + lur.u.version = lum->u.version; + break; + case LTTNG_UST_TRACEPOINT_LIST_GET: + memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint)); + break; + } } ret = send_reply(sock, &lur); if (ret < 0) { @@ -383,7 +391,7 @@ error: } static -void cleanup_sock_info(struct sock_info *sock_info) +void cleanup_sock_info(struct sock_info *sock_info, int exiting) { int ret; @@ -402,7 +410,13 @@ void cleanup_sock_info(struct sock_info *sock_info) sock_info->root_handle = -1; } sock_info->constructor_sem_posted = 0; - if (sock_info->wait_shm_mmap) { + /* + * wait_shm_mmap is used by listener threads outside of the + * ust lock, so we cannot tear it down ourselves, because we + * cannot join on these threads. Leave this task to the OS + * process exit. + */ + if (!exiting && sock_info->wait_shm_mmap) { ret = munmap(sock_info->wait_shm_mmap, sysconf(_SC_PAGE_SIZE)); if (ret) { ERR("Error unmapping wait shm"); @@ -819,6 +833,14 @@ void __attribute__((constructor)) lttng_ust_init(void) 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(); + /* * We want precise control over the order in which we construct * our sub-libraries vs starting to receive commands from @@ -876,10 +898,17 @@ void __attribute__((constructor)) lttng_ust_init(void) static void lttng_ust_cleanup(int exiting) { - cleanup_sock_info(&global_apps); + cleanup_sock_info(&global_apps, exiting); if (local_apps.allowed) { - cleanup_sock_info(&local_apps); + cleanup_sock_info(&local_apps, exiting); } + /* + * The teardown in this function all affect data structures + * accessed under the UST lock by the listener thread. This + * lock, along with the lttng_ust_comm_should_quit flag, ensure + * that none of these threads are accessing this data at this + * point. + */ lttng_ust_abi_exit(); lttng_ust_events_exit(); ltt_ring_buffer_client_discard_exit(); @@ -913,6 +942,7 @@ void __attribute__((destructor)) lttng_ust_exit(void) lttng_ust_comm_should_quit = 1; ust_unlock(); + /* cancel threads */ ret = pthread_cancel(global_apps.ust_listener); if (ret) { ERR("Error cancelling global ust listener thread"); @@ -923,6 +953,14 @@ void __attribute__((destructor)) lttng_ust_exit(void) ERR("Error cancelling local ust listener thread"); } } + /* + * Do NOT join threads: use of sys_futex makes it impossible to + * join the threads without using async-cancel, but async-cancel + * is delivered by a signal, which could hit the target thread + * anywhere in its code path, including while the ust_lock() is + * held, causing a deadlock for the other thread. Let the OS + * cleanup the threads if there are stalled in a syscall. + */ lttng_ust_cleanup(1); }