#define _LGPL_SOURCE
#include <sys/types.h>
#include <sys/socket.h>
-#include <sys/prctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <lttng/ust-events.h>
#include <lttng/ust-abi.h>
#include <lttng/ust.h>
+#include <lttng/ust-error.h>
#include <ust-comm.h>
#include <usterr-signal-safe.h>
+#include <helper.h>
#include "tracepoint-internal.h"
#include "ltt-tracer-core.h"
+#include "compat.h"
+#include "../libringbuffer/tlsfixup.h"
/*
* Has lttng ust comm constructor been called ?
*/
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.
*/
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)
{
* Disallow per-user tracing for setuid binaries.
*/
if (uid != geteuid()) {
- local_apps.allowed = 0;
+ assert(local_apps.allowed == 0);
return 0;
- } else {
- local_apps.allowed = 1;
}
home_dir = (const char *) getenv("HOME");
- if (!home_dir)
+ if (!home_dir) {
+ WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
+ assert(local_apps.allowed == 0);
return -ENOENT;
+ }
+ local_apps.allowed = 1;
snprintf(local_apps.sock_path, PATH_MAX,
DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
snprintf(local_apps.wait_shm_path, PATH_MAX,
int register_app_to_sessiond(int socket)
{
ssize_t ret;
- int prctl_ret;
struct {
uint32_t major;
uint32_t minor;
reg_msg.uid = getuid();
reg_msg.gid = getgid();
reg_msg.bits_per_long = CAA_BITS_PER_LONG;
- prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0);
- if (prctl_ret) {
- ERR("Error executing prctl");
- return -errno;
- }
+ lttng_ust_getprocname(reg_msg.name);
ret = ustcomm_send_unix_sock(socket, ®_msg, sizeof(reg_msg));
if (ret >= 0 && ret != sizeof(reg_msg))
case sizeof(*lur):
DBG("message successfully sent");
return 0;
- case -1:
- if (errno == ECONNRESET) {
- printf("remote end closed connection\n");
+ default:
+ if (len == -ECONNRESET) {
+ DBG("remote end closed connection");
return 0;
}
- return -1;
- default:
- printf("incorrect message size: %zd\n", len);
- return -1;
+ if (len < 0)
+ return len;
+ DBG("incorrect message size: %zd", len);
+ return -EINVAL;
}
}
const struct lttng_ust_objd_ops *ops;
struct ustcomm_ust_reply lur;
int shm_fd, wait_fd;
+ union ust_args args;
+ ssize_t len;
ust_lock();
else
ret = lttng_ust_objd_unref(lum->handle);
break;
+ case LTTNG_UST_FILTER:
+ {
+ /* Receive filter data */
+ struct lttng_ust_filter_bytecode *bytecode;
+
+ if (lum->u.filter.data_size > FILTER_BYTECODE_MAX_LEN) {
+ ERR("Filter data size is too large: %u bytes",
+ lum->u.filter.data_size);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ if (lum->u.filter.reloc_offset > lum->u.filter.data_size) {
+ ERR("Filter reloc offset %u is not within data",
+ lum->u.filter.reloc_offset);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size);
+ if (!bytecode) {
+ ret = -ENOMEM;
+ goto error;
+ }
+ len = ustcomm_recv_unix_sock(sock, bytecode->data,
+ lum->u.filter.data_size);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ free(bytecode);
+ goto error;
+ default:
+ if (len == lum->u.filter.data_size) {
+ DBG("filter data received");
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection", sock_info->name);
+ ret = len;
+ free(bytecode);
+ goto error;
+ }
+ ret = len;
+ goto end;
+ } else {
+ DBG("incorrect filter data message size: %zd", len);
+ ret = -EINVAL;
+ free(bytecode);
+ goto end;
+ }
+ }
+ bytecode->len = lum->u.filter.data_size;
+ bytecode->reloc_offset = lum->u.filter.reloc_offset;
+ if (ops->cmd) {
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) bytecode,
+ &args);
+ if (ret) {
+ free(bytecode);
+ }
+ /* don't free bytecode if everything went fine. */
+ } else {
+ ret = -ENOSYS;
+ free(bytecode);
+ }
+ break;
+ }
default:
if (ops->cmd)
ret = ops->cmd(lum->handle, lum->cmd,
- (unsigned long) &lum->u);
+ (unsigned long) &lum->u,
+ &args);
else
ret = -ENOSYS;
break;
lur.cmd = lum->cmd;
lur.ret_val = ret;
if (ret >= 0) {
- lur.ret_code = USTCOMM_OK;
+ lur.ret_code = LTTNG_UST_OK;
} else {
- //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.
+ * Use -LTTNG_UST_ERR as wildcard for UST internal
+ * error that are not caused by the transport, except if
+ * we already have a more precise error message to
+ * report.
*/
- lur.u.stream.memory_map_size = lum->u.stream.memory_map_size;
- shm_fd = lum->u.stream.shm_fd;
- wait_fd = lum->u.stream.wait_fd;
- break;
- case LTTNG_UST_METADATA:
- case LTTNG_UST_CHANNEL:
- lur.u.channel.memory_map_size = lum->u.channel.memory_map_size;
- shm_fd = lum->u.channel.shm_fd;
- wait_fd = lum->u.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_list_entry,
- lum->u.tracepoint_list_entry,
- LTTNG_UST_SYM_NAME_LEN);
- break;
+ if (ret > -LTTNG_UST_ERR)
+ lur.ret_code = -LTTNG_UST_ERR;
+ else
+ lur.ret_code = ret;
+ }
+ 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) {
- perror("error sending reply");
+ DBG("error sending reply");
goto error;
}
if ((lum->cmd == LTTNG_UST_STREAM
|| lum->cmd == LTTNG_UST_CHANNEL
|| lum->cmd == LTTNG_UST_METADATA)
- && lur.ret_code == USTCOMM_OK) {
+ && lur.ret_code == LTTNG_UST_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;
+ ERR("send shm_fd");
+ 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));
perror("send wait_fd");
goto error;
}
+ if (sendret) {
+ ret = sendret;
+ goto error;
+ }
+ }
+ /*
+ * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
+ * after the reply.
+ */
+ if (lur.ret_code == LTTNG_UST_OK) {
+ switch (lum->cmd) {
+ case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
+ len = ustcomm_send_unix_sock(sock,
+ &args.field_list.entry,
+ sizeof(args.field_list.entry));
+ if (len < 0) {
+ ret = len;
+ goto error;
+ }
+ if (len != sizeof(args.field_list.entry)) {
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ }
+ /*
+ * We still have the memory map reference, and the fds have been
+ * sent to the sessiond. We can therefore close those fds. Note
+ * that we keep the write side of the wait_fd open, but close
+ * the read side.
+ */
+ if (lur.ret_code == LTTNG_UST_OK) {
+ switch (lum->cmd) {
+ case LTTNG_UST_STREAM:
+ if (shm_fd >= 0) {
+ ret = close(shm_fd);
+ if (ret) {
+ PERROR("Error closing stream shm_fd");
+ }
+ *args.stream.shm_fd = -1;
+ }
+ if (wait_fd >= 0) {
+ ret = close(wait_fd);
+ if (ret) {
+ PERROR("Error closing stream wait_fd");
+ }
+ *args.stream.wait_fd = -1;
+ }
+ break;
+ case LTTNG_UST_METADATA:
+ case LTTNG_UST_CHANNEL:
+ if (shm_fd >= 0) {
+ ret = close(shm_fd);
+ if (ret) {
+ PERROR("Error closing channel shm_fd");
+ }
+ *args.channel.shm_fd = -1;
+ }
+ if (wait_fd >= 0) {
+ ret = close(wait_fd);
+ if (ret) {
+ PERROR("Error closing channel wait_fd");
+ }
+ *args.channel.wait_fd = -1;
+ }
+ break;
+ }
}
+
error:
ust_unlock();
return ret;
}
static
-void cleanup_sock_info(struct sock_info *sock_info)
+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");
}
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");
* 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;
* shared memory map will have been created.
*/
pid = wait(&status);
- if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+ if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
wait_shm_fd = -1;
goto end;
}
ret = ftruncate(wait_shm_fd, mmap_size);
if (ret) {
PERROR("ftruncate");
- exit(EXIT_FAILURE);
+ _exit(EXIT_FAILURE);
}
- exit(EXIT_SUCCESS);
+ _exit(EXIT_SUCCESS);
}
/*
* For local shm, we need to have rw access to accept
*/
if (!sock_info->global && errno != EACCES) {
ERR("Error opening shm %s", sock_info->wait_shm_path);
- exit(EXIT_FAILURE);
+ _exit(EXIT_FAILURE);
}
/*
* The shm exists, but we cannot open it RW. Report
* success.
*/
- exit(EXIT_SUCCESS);
+ _exit(EXIT_SUCCESS);
} else {
return -1;
}
if (ret < 0) {
if (errno == EFAULT) {
wait_poll_fallback = 1;
- WARN(
+ DBG(
"Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
"do not support FUTEX_WAKE on read-only memory mappings correctly. "
"Please upgrade your kernel "
"(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
"mainline). LTTng-UST will use polling mode fallback.");
+ if (ust_debug())
+ PERROR("futex");
}
- PERROR("futex");
}
}
return;
* This thread does not allocate any resource, except within
* handle_message, within mutex protection. This mutex protects against
* fork and exit.
- * The other moment it allocates resources is at socket connexion, which
+ * The other moment it allocates resources is at socket connection, which
* is also protected by the mutex.
*/
static
}
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);
}
len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum));
switch (len) {
case 0: /* orderly shutdown */
- DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name);
+ DBG("%s ltt-sessiond has performed an orderly shutdown", sock_info->name);
ust_lock();
/*
* Either sessiond has shutdown or refused us by closing the socket.
ust_unlock();
goto end;
case sizeof(lum):
- DBG("message received\n");
+ DBG("message received");
ret = handle_message(sock_info, sock, &lum);
- if (ret < 0) {
+ if (ret) {
ERR("Error handling message for %s socket", sock_info->name);
}
continue;
- case -1:
- DBG("Receive failed from lttng-sessiond with errno %d", errno);
- if (errno == ECONNRESET) {
- ERR("%s remote end closed connection\n", sock_info->name);
+ default:
+ if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ } else {
+ DBG("incorrect message size (%s socket): %zd", sock_info->name, len);
+ }
+ if (len == -ECONNRESET) {
+ DBG("%s remote end closed connection", sock_info->name);
goto end;
}
goto end;
- default:
- ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len);
- continue;
}
}
* sessiond monitoring thread: monitor presence of global and per-user
* sessiond by polling the application common named pipe.
*/
-/* TODO */
-
void __attribute__((constructor)) lttng_ust_init(void)
{
struct timespec constructor_timeout;
+ sigset_t sig_all_blocked, orig_parent_mask;
+ pthread_attr_t thread_attr;
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();
+ lttng_fixup_procname_tls();
+
/*
* We want precise control over the order in which we construct
* our sub-libraries vs starting to receive commands from
ret = setup_local_apps();
if (ret) {
- ERR("Error setting up to local apps");
+ DBG("local apps setup returned %d", ret);
+ }
+
+ /* 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(&local_apps.ust_listener, NULL,
- ust_listener_thread, &local_apps);
+ ret = pthread_attr_init(&thread_attr);
+ if (ret) {
+ ERR("pthread_attr_init: %s", strerror(ret));
+ }
+ ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
+ if (ret) {
+ ERR("pthread_attr_setdetachstate: %s", strerror(ret));
+ }
+
+ ret = pthread_create(&global_apps.ust_listener, &thread_attr,
+ 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, &thread_attr,
+ ust_listener_thread, &local_apps);
+ if (ret) {
+ ERR("pthread_create local: %s", strerror(ret));
+ }
} else {
handle_register_done(&local_apps);
}
+ ret = pthread_attr_destroy(&thread_attr);
+ if (ret) {
+ ERR("pthread_attr_destroy: %s", strerror(ret));
+ }
+
+ /* 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 */
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();
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");
+ 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));
}
}
+ /*
+ * 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);
}
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);
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 */
*/
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();