[glibc/maskray/lld] support: Add support_small_thread_stack_size

[glibc/maskray/lld] support: Add support_small_thread_stack_size

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ecdb06cdf22c7d37699f5420265245ff31c53b3c

commit ecdb06cdf22c7d37699f5420265245ff31c53b3c
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Tue Dec 29 11:52:41 2020 -0300

    support: Add support_small_thread_stack_size
    
    It returns the minimum stack size large enough to cover most internal
    glibc stack usage.

Diff:
---
 support/support_set_small_thread_stack_size.c | 12 +++++++++---
 support/xthread.h                             |  2 ++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/support/support_set_small_thread_stack_size.c b/support/support_set_small_thread_stack_size.c
index 3b0426e28e..faa2e2f857 100644
--- a/support/support_set_small_thread_stack_size.c
+++ b/support/support_set_small_thread_stack_size.c
@@ -20,8 +20,8 @@
 #include <pthread.h>
 #include <support/xthread.h>
 
-void
-support_set_small_thread_stack_size (pthread_attr_t *attr)
+size_t
+support_small_thread_stack_size (void)
 {
   /* Some architectures have too small values for PTHREAD_STACK_MIN
      which cannot be used for creating threads.  Ensure that the stack
@@ -31,5 +31,11 @@ support_set_small_thread_stack_size (pthread_attr_t *attr)
   if (stack_size < PTHREAD_STACK_MIN)
     stack_size = PTHREAD_STACK_MIN;
 #endif
-  xpthread_attr_setstacksize (attr, stack_size);
+  return stack_size;
+}
+
+void
+support_set_small_thread_stack_size (pthread_attr_t *attr)
+{
+  xpthread_attr_setstacksize (attr, support_small_thread_stack_size ());
 }
diff --git a/support/xthread.h b/support/xthread.h
index d57cef6db1..c2086db347 100644
--- a/support/xthread.h
+++ b/support/xthread.h
@@ -75,6 +75,8 @@ void xpthread_attr_setstacksize (pthread_attr_t *attr,
 void xpthread_attr_setguardsize (pthread_attr_t *attr,
 				 size_t guardsize);
 
+/* Return the stack size used on support_set_small_thread_stack_size.  */
+size_t support_small_thread_stack_size (void);
 /* Set the stack size in ATTR to a small value, but still large enough
    to cover most internal glibc stack usage.  */
 void support_set_small_thread_stack_size (pthread_attr_t *attr);