Add common util to set thread name

[lttng-tools.git] / src / common / defaults.c

diff --git a/src/common/defaults.c b/src/common/defaults.c
index 00a0265414baaf693a0eb687e8ce05b9a8f23907..ee48c436879a7d356f6e649b5cd3b89a419533bc 100644 (file)
--- a/src/common/defaults.c
+++ b/src/common/defaults.c
@@ -1,18 +1,8 @@
 /*
- * Copyright (C) 2012 - Simon Marchi <simon.marchi@polymtl.ca>
+ * Copyright (C) 2012 Simon Marchi <simon.marchi@polymtl.ca>
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License, version 2 only, as
- * published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #define _LGPL_SOURCE
@@ -27,9 +17,8 @@
 #include "align.h"
 #include "error.h"
 
-static bool pthread_attr_init_done;
+static int pthread_attr_init_done;
 static pthread_attr_t tattr;
-static pthread_mutex_t tattr_lock = PTHREAD_MUTEX_INITIALIZER;
 
 LTTNG_HIDDEN
 size_t default_get_channel_subbuf_size(void)
@@ -64,55 +53,93 @@ size_t default_get_ust_uid_channel_subbuf_size(void)
 LTTNG_HIDDEN
 pthread_attr_t *default_pthread_attr(void)
 {
-       int ret = 0;
-       size_t ptstacksize;
-       struct rlimit rlim;
+       if (pthread_attr_init_done) {
+               return &tattr;
+       }
 
-       pthread_mutex_lock(&tattr_lock);
+       WARN("Uninitialized pthread attributes, using libc defaults.");
+       return NULL;
+}
 
-       /* Return cached value. */
-       if (pthread_attr_init_done) {
-               goto end;
+static void __attribute__((constructor)) init_default_pthread_attr(void)
+{
+       int ret;
+       struct rlimit rlim;
+       size_t pthread_ss, system_ss, selected_ss;
+
+       ret = pthread_attr_init(&tattr);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_attr_init");
+               goto error;
        }
 
        /* Get system stack size limits. */
        ret = getrlimit(RLIMIT_STACK, &rlim);
        if (ret < 0) {
                PERROR("getrlimit");
-               goto error;
+               goto error_destroy;
        }
        DBG("Stack size limits: soft %lld, hard %lld bytes",
                        (long long) rlim.rlim_cur,
                        (long long) rlim.rlim_max);
 
+       /*
+        * getrlimit() may return a stack size of "-1", meaning "unlimited".
+        * In this case, we impose a known-good default minimum value which will
+        * override the libc's default stack size if it is smaller.
+        */
+       system_ss = rlim.rlim_cur != -1 ? rlim.rlim_cur :
+                       DEFAULT_LTTNG_THREAD_STACK_SIZE;
+
        /* Get pthread default thread stack size. */
-       ret = pthread_attr_getstacksize(&tattr, &ptstacksize);
+       ret = pthread_attr_getstacksize(&tattr, &pthread_ss);
        if (ret < 0) {
                PERROR("pthread_attr_getstacksize");
-               goto error;
+               goto error_destroy;
        }
-       DBG("Default pthread stack size is %zu bytes", ptstacksize);
-
-       /* Check if the default pthread stack size honors ulimits. */
-       if (ptstacksize < rlim.rlim_cur) {
-               DBG("Your libc doesn't honor stack size limits, setting thread stack size to soft limit (%lld bytes)",
-                               (long long) rlim.rlim_cur);
-
-               /* Create pthread_attr_t struct with ulimit stack size. */
-               ret = pthread_attr_setstacksize(&tattr, rlim.rlim_cur);
-               if (ret < 0) {
-                       PERROR("pthread_attr_setstacksize");
-                       goto error;
-               }
+       DBG("Default pthread stack size is %zu bytes", pthread_ss);
+
+       selected_ss = max_t(size_t, pthread_ss, system_ss);
+       if (selected_ss < DEFAULT_LTTNG_THREAD_STACK_SIZE) {
+               DBG("Default stack size is too small, setting it to %zu bytes",
+                       (size_t) DEFAULT_LTTNG_THREAD_STACK_SIZE);
+               selected_ss = DEFAULT_LTTNG_THREAD_STACK_SIZE;
+       }
+
+       if (rlim.rlim_max > 0 && selected_ss > rlim.rlim_max) {
+               WARN("Your system's stack size restrictions (%zu bytes) may be too low for the LTTng daemons to function properly, please set the stack size limit to at least %zu bytes to ensure reliable operation",
+                       (size_t) rlim.rlim_max, (size_t) DEFAULT_LTTNG_THREAD_STACK_SIZE);
+               selected_ss = (size_t) rlim.rlim_max;
        }
 
-       /* Enable cached value. */
-       pthread_attr_init_done = true;
-end:
-       pthread_mutex_unlock(&tattr_lock);
-       return &tattr;
+       ret = pthread_attr_setstacksize(&tattr, selected_ss);
+       if (ret < 0) {
+               PERROR("pthread_attr_setstacksize");
+               goto error_destroy;
+       }
+       pthread_attr_init_done = 1;
 error:
-       pthread_mutex_unlock(&tattr_lock);
-       WARN("Failed to initialize pthread attributes, using libc defaults.");
-       return NULL;
+       return;
+error_destroy:
+       ret = pthread_attr_destroy(&tattr);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_attr_destroy");
+       }
+}
+
+static void __attribute__((destructor)) fini_default_pthread_attr(void)
+{
+       int ret;
+
+       if (!pthread_attr_init_done) {
+               return;
+       }
+
+       ret = pthread_attr_destroy(&tattr);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_attr_destroy");
+       }
 }