Free list not mutex protected in thread pool (ITS#1839)

[simon@sxw.org.uk]

Full_Name: Simon Wilkinson
Version: CVS HEAD / 2.1.1beta
OS: Linux
URL: 
Submission from: (NULL) (62.6.94.189)


Additions to the thread pool free list in ldap_int_thread_pool_wrapper 
(libldap_r/tpool.c:402) aren't protected by the per-pool mutex.

Whilst my understanding of this code is somewhat cursory, I believe that this
may lead to race conditions with the handling of the thread pool information.
The
fix, which seems to run correctly under Linux pthreads is:

--- tpool.c~    Tue Apr  2 23:57:53 2002
+++ tpool.c     Mon May 27 11:31:42 2002
@@ -399,7 +399,11 @@
                ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 
                (ctx->ltc_start_routine)(ctx->ltc_arg);
+
+               ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
                LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
+               ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+
                ldap_pvt_thread_yield();
 
                /* if we use an idle timer, here's