New API to set default thread attributes

This patch introduces two new convenience functions to set the default
thread attributes used for creating threads.  This allows a programmer
to set the default thread attributes just once in a process and then
run pthread_create without additional attributes.

1 files changed, 10 insertions, 2 deletions

diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 56bf2570f8..1e0fe1f18d 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -358,7 +358,14 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 
   /* Get the stack size from the attribute if it is set.  Otherwise we
      use the default we determined at start time.  */
-  size = attr->stacksize ?: __default_pthread_attr.stacksize;
+  if (attr->stacksize != 0)
+    size = attr->stacksize;
+  else
+    {
+      lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
+      size = __default_pthread_attr.stacksize;
+      lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
+    }
 
   /* Get memory for the stack.  */
   if (__builtin_expect (attr->flags & ATTR_FLAG_STACKADDR, 0))
@@ -919,8 +926,9 @@ __reclaim_stacks (void)
 
   in_flight_stack = 0;
 
-  /* Initialize the lock.  */
+  /* Initialize locks.  */
   stack_cache_lock = LLL_LOCK_INITIALIZER;
+  __default_pthread_attr_lock = LLL_LOCK_INITIALIZER;
 }