nptl: Move stack cache management, __libpthread_freeres into libc

This replaces the FREE_P macro with the __nptl_stack_in_use inline
function.  stack_list_del is renamed to __nptl_stack_list_del,
stack_list_add to __nptl_stack_list_add, __deallocate_stack to
__nptl_deallocate_stack, free_stacks to __nptl_free_stacks.

It is convenient to move __libpthread_freeres into libc at the
same time.  This removes the temporary __default_pthread_attr_freeres
export and restores full freeres coverage for __default_pthread_attr.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

9 files changed, 202 insertions, 153 deletions

diff --git a/nptl/Makefile b/nptl/Makefile
index 2ef09fb..1b32a52 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -44,9 +44,11 @@ routines = \
   libc_multiple_threads \
   libc_pthread_init \
   lowlevellock \
+  nptl-stack \
   nptl_deallocate_tsd \
   nptl_nthreads \
   nptl_setxid \
+  nptlfreeres \
   old_pthread_atfork \
   old_pthread_cond_broadcast \
   old_pthread_cond_destroy \
@@ -182,7 +184,6 @@ libpthread-routines = \
   events \
   libpthread-compat \
   nptl-init \
-  nptlfreeres \
   pt-interp \
   pthread_attr_getaffinity \
   pthread_attr_getguardsize \
diff --git a/nptl/Versions b/nptl/Versions
index de025e1..93219d2 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -303,7 +303,6 @@ libc {
   }
   GLIBC_PRIVATE {
     __default_pthread_attr;
-    __default_pthread_attr_freeres;
     __default_pthread_attr_lock;
     __futex_abstimed_wait64;
     __futex_abstimed_wait_cancelable64;
@@ -320,9 +319,12 @@ libc {
     __lll_trylock_elision;
     __lll_unlock_elision;
     __mutex_aconf;
+    __nptl_deallocate_stack;
     __nptl_deallocate_tsd;
     __nptl_nthreads;
     __nptl_setxid_sighandler;
+    __nptl_stack_list_add;
+    __nptl_stack_list_del;
     __pthread_attr_copy;
     __pthread_attr_destroy;
     __pthread_attr_init;
@@ -459,7 +461,6 @@ libpthread {
   }
 
   GLIBC_PRIVATE {
-    __libpthread_freeres;
     __pthread_clock_gettime;
     __pthread_clock_settime;
     __pthread_get_minstack;
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 8672e89..c0a5c4d 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -31,7 +31,7 @@
 #include <lowlevellock.h>
 #include <futex-internal.h>
 #include <kernel-features.h>
-
+#include <nptl-stack.h>
 
 #ifndef NEED_SEPARATE_REGISTER_STACK
 
@@ -92,56 +92,6 @@
 # define MAP_STACK 0
 #endif
 
-/* This yields the pointer that TLS support code calls the thread pointer.  */
-#if TLS_TCB_AT_TP
-# define TLS_TPADJ(pd) (pd)
-#elif TLS_DTV_AT_TP
-# define TLS_TPADJ(pd) ((struct pthread *)((char *) (pd) + TLS_PRE_TCB_SIZE))
-#endif
-
-/* Cache handling for not-yet free stacks.  */
-
-/* Maximum size in kB of cache.  */
-static size_t stack_cache_maxsize = 40 * 1024 * 1024; /* 40MiBi by default.  */
-
-/* Check whether the stack is still used or not.  */
-#define FREE_P(descr) ((descr)->tid <= 0)
-
-
-static void
-stack_list_del (list_t *elem)
-{
-  GL (dl_in_flight_stack) = (uintptr_t) elem;
-
-  atomic_write_barrier ();
-
-  list_del (elem);
-
-  atomic_write_barrier ();
-
-  GL (dl_in_flight_stack) = 0;
-}
-
-
-static void
-stack_list_add (list_t *elem, list_t *list)
-{
-  GL (dl_in_flight_stack) = (uintptr_t) elem | 1;
-
-  atomic_write_barrier ();
-
-  list_add (elem, list);
-
-  atomic_write_barrier ();
-
-  GL (dl_in_flight_stack) = 0;
-}
-
-
-/* We create a double linked list of all cache entries.  Double linked
-   because this allows removing entries from the end.  */
-
-
 /* Get a stack frame from the cache.  We have to match by size since
    some blocks might be too small or far too large.  */
 static struct pthread *
@@ -164,7 +114,7 @@ get_cached_stack (size_t *sizep, void **memp)
       struct pthread *curr;
 
       curr = list_entry (entry, struct pthread, list);
-      if (FREE_P (curr) && curr->stackblock_size >= size)
+      if (__nptl_stack_in_use (curr) && curr->stackblock_size >= size)
 	{
 	  if (curr->stackblock_size == size)
 	    {
@@ -193,10 +143,10 @@ get_cached_stack (size_t *sizep, void **memp)
   result->setxid_futex = -1;
 
   /* Dequeue the entry.  */
-  stack_list_del (&result->list);
+  __nptl_stack_list_del (&result->list);
 
   /* And add to the list of stacks in use.  */
-  stack_list_add (&result->list, &GL (dl_stack_used));
+  __nptl_stack_list_add (&result->list, &GL (dl_stack_used));
 
   /* And decrease the cache size.  */
   GL (dl_stack_cache_actsize) -= result->stackblock_size;
@@ -229,68 +179,6 @@ get_cached_stack (size_t *sizep, void **memp)
   return result;
 }
 
-
-/* Free stacks until cache size is lower than LIMIT.  */
-static void
-free_stacks (size_t limit)
-{
-  /* We reduce the size of the cache.  Remove the last entries until
-     the size is below the limit.  */
-  list_t *entry;
-  list_t *prev;
-
-  /* Search from the end of the list.  */
-  list_for_each_prev_safe (entry, prev, &GL (dl_stack_cache))
-    {
-      struct pthread *curr;
-
-      curr = list_entry (entry, struct pthread, list);
-      if (FREE_P (curr))
-	{
-	  /* Unlink the block.  */
-	  stack_list_del (entry);
-
-	  /* Account for the freed memory.  */
-	  GL (dl_stack_cache_actsize) -= curr->stackblock_size;
-
-	  /* Free the memory associated with the ELF TLS.  */
-	  _dl_deallocate_tls (TLS_TPADJ (curr), false);
-
-	  /* Remove this block.  This should never fail.  If it does
-	     something is really wrong.  */
-	  if (__munmap (curr->stackblock, curr->stackblock_size) != 0)
-	    abort ();
-
-	  /* Maybe we have freed enough.  */
-	  if (GL (dl_stack_cache_actsize) <= limit)
-	    break;
-	}
-    }
-}
-
-/* Free all the stacks on cleanup.  */
-void
-__nptl_stacks_freeres (void)
-{
-  free_stacks (0);
-}
-
-/* Add a stack frame which is not used anymore to the stack.  Must be
-   called with the cache lock held.  */
-static inline void
-__attribute ((always_inline))
-queue_stack (struct pthread *stack)
-{
-  /* We unconditionally add the stack to the list.  The memory may
-     still be in use but it will not be reused until the kernel marks
-     the stack as not used anymore.  */
-  stack_list_add (&stack->list, &GL (dl_stack_cache));
-
-  GL (dl_stack_cache_actsize) += stack->stackblock_size;
-  if (__glibc_unlikely (GL (dl_stack_cache_actsize) > stack_cache_maxsize))
-    free_stacks (stack_cache_maxsize);
-}
-
 /* Return the guard page position on allocated stack.  */
 static inline char *
 __attribute ((always_inline))
@@ -588,7 +476,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 	  lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
 
 	  /* And add to the list of stacks in use.  */
-	  stack_list_add (&pd->list, &GL (dl_stack_used));
+	  __nptl_stack_list_add (&pd->list, &GL (dl_stack_used));
 
 	  lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
 
@@ -630,7 +518,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 	      lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
 
 	      /* Remove the thread from the list.  */
-	      stack_list_del (&pd->list);
+	      __nptl_stack_list_del (&pd->list);
 
 	      lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
 
@@ -731,26 +619,3 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 
   return 0;
 }
-
-
-void
-__deallocate_stack (struct pthread *pd)
-{
-  lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
-
-  /* Remove the thread from the list of threads with user defined
-     stacks.  */
-  stack_list_del (&pd->list);
-
-  /* Not much to do.  Just free the mmap()ed memory.  Note that we do
-     not reset the 'used' flag in the 'tid' field.  This is done by
-     the kernel.  If no thread has been created yet this field is
-     still zero.  */
-  if (__glibc_likely (! pd->user_stack))
-    (void) queue_stack (pd);
-  else
-    /* Free the memory associated with the ELF TLS.  */
-    _dl_deallocate_tls (TLS_TPADJ (pd), false);
-
-  lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
-}
diff --git a/nptl/descr.h b/nptl/descr.h
index d423a53..3de9535 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -416,5 +416,11 @@ struct pthread
   (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
 } __attribute ((aligned (TCB_ALIGNMENT)));
 
+/* This yields the pointer that TLS support code calls the thread pointer.  */
+#if TLS_TCB_AT_TP
+# define TLS_TPADJ(pd) (pd)
+#elif TLS_DTV_AT_TP
+# define TLS_TPADJ(pd) ((struct pthread *)((char *) (pd) + TLS_PRE_TCB_SIZE))
+#endif
 
 #endif	/* descr.h */
diff --git a/nptl/nptl-stack.c b/nptl/nptl-stack.c
new file mode 100644
index 0000000..7853c10
--- /dev/null
+++ b/nptl/nptl-stack.c
@@ -0,0 +1,130 @@
+/* Stack cache management for NPTL.
+   Copyright (C) 2002-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <nptl-stack.h>
+#include <ldsodefs.h>
+
+/* Maximum size in kB of cache.  40MiBi by default.  */
+static const size_t stack_cache_maxsize = 40 * 1024 * 1024;
+
+void
+__nptl_stack_list_del (list_t *elem)
+{
+  GL (dl_in_flight_stack) = (uintptr_t) elem;
+
+  atomic_write_barrier ();
+
+  list_del (elem);
+
+  atomic_write_barrier ();
+
+  GL (dl_in_flight_stack) = 0;
+}
+libc_hidden_def (__nptl_stack_list_del)
+
+void
+__nptl_stack_list_add (list_t *elem, list_t *list)
+{
+  GL (dl_in_flight_stack) = (uintptr_t) elem | 1;
+
+  atomic_write_barrier ();
+
+  list_add (elem, list);
+
+  atomic_write_barrier ();
+
+  GL (dl_in_flight_stack) = 0;
+}
+libc_hidden_def (__nptl_stack_list_add)
+
+void
+__nptl_free_stacks (size_t limit)
+{
+  /* We reduce the size of the cache.  Remove the last entries until
+     the size is below the limit.  */
+  list_t *entry;
+  list_t *prev;
+
+  /* Search from the end of the list.  */
+  list_for_each_prev_safe (entry, prev, &GL (dl_stack_cache))
+    {
+      struct pthread *curr;
+
+      curr = list_entry (entry, struct pthread, list);
+      if (__nptl_stack_in_use (curr))
+	{
+	  /* Unlink the block.  */
+	  __nptl_stack_list_del (entry);
+
+	  /* Account for the freed memory.  */
+	  GL (dl_stack_cache_actsize) -= curr->stackblock_size;
+
+	  /* Free the memory associated with the ELF TLS.  */
+	  _dl_deallocate_tls (TLS_TPADJ (curr), false);
+
+	  /* Remove this block.  This should never fail.  If it does
+	     something is really wrong.  */
+	  if (__munmap (curr->stackblock, curr->stackblock_size) != 0)
+	    abort ();
+
+	  /* Maybe we have freed enough.  */
+	  if (GL (dl_stack_cache_actsize) <= limit)
+	    break;
+	}
+    }
+}
+
+/* Add a stack frame which is not used anymore to the stack.  Must be
+   called with the cache lock held.  */
+static inline void
+__attribute ((always_inline))
+queue_stack (struct pthread *stack)
+{
+  /* We unconditionally add the stack to the list.  The memory may
+     still be in use but it will not be reused until the kernel marks
+     the stack as not used anymore.  */
+  __nptl_stack_list_add (&stack->list, &GL (dl_stack_cache));
+
+  GL (dl_stack_cache_actsize) += stack->stackblock_size;
+  if (__glibc_unlikely (GL (dl_stack_cache_actsize) > stack_cache_maxsize))
+    __nptl_free_stacks (stack_cache_maxsize);
+}
+
+void
+__nptl_deallocate_stack (struct pthread *pd)
+{
+  lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
+
+  /* Remove the thread from the list of threads with user defined
+     stacks.  */
+  __nptl_stack_list_del (&pd->list);
+
+  /* Not much to do.  Just free the mmap()ed memory.  Note that we do
+     not reset the 'used' flag in the 'tid' field.  This is done by
+     the kernel.  If no thread has been created yet this field is
+     still zero.  */
+  if (__glibc_likely (! pd->user_stack))
+    (void) queue_stack (pd);
+  else
+    /* Free the memory associated with the ELF TLS.  */
+    _dl_deallocate_tls (TLS_TPADJ (pd), false);
+
+  lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
+}
+libc_hidden_def (__nptl_deallocate_stack)
diff --git a/nptl/nptl-stack.h b/nptl/nptl-stack.h
new file mode 100644
index 0000000..8631b61
--- /dev/null
+++ b/nptl/nptl-stack.h
@@ -0,0 +1,50 @@
+/* Stack cache management for NPTL.
+   Copyright (C) 2002-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _NPTL_STACK_H
+#define _NPTL_STACK_H
+
+#include <descr.h>
+#include <list.h>
+#include <stdbool.h>
+
+/* Check whether the stack is still used or not.  */
+static inline bool
+__nptl_stack_in_use (struct pthread *pd)
+{
+  return pd->tid <= 0;
+}
+
+/* Remove the stack ELEM from its list.  */
+void __nptl_stack_list_del (list_t *elem);
+libc_hidden_proto (__nptl_stack_list_del)
+
+/* Add ELEM to a stack list.  LIST can be either &GL (dl_stack_used)
+   or &GL (dl_stack_cache).  */
+void __nptl_stack_list_add (list_t *elem, list_t *list);
+libc_hidden_proto (__nptl_stack_list_add)
+
+/* Free allocated stack.  */
+extern void __nptl_deallocate_stack (struct pthread *pd);
+libc_hidden_proto (__nptl_deallocate_stack)
+
+/* Free stacks until cache size is lower than LIMIT.  */
+void __nptl_free_stacks (size_t limit) attribute_hidden;
+
+#endif /* _NPTL_STACK_H */
diff --git a/nptl/nptlfreeres.c b/nptl/nptlfreeres.c
index 4833f04..527b5ee 100644
--- a/nptl/nptlfreeres.c
+++ b/nptl/nptlfreeres.c
@@ -19,6 +19,7 @@
 #include <set-hooks.h>
 #include <libc-symbols.h>
 #include <pthreadP.h>
+#include <nptl-stack.h>
 
 /* Free libpthread.so resources.
    Note: Caller ensures we are called only once.  */
@@ -26,5 +27,5 @@ void
 __libpthread_freeres (void)
 {
   call_function_static_weak (__default_pthread_attr_freeres);
-  call_function_static_weak (__nptl_stacks_freeres);
+  __nptl_free_stacks (0);
 }
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 8466332..505d0f0 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -203,7 +203,7 @@ libc_hidden_proto (__default_pthread_attr)
 extern int __default_pthread_attr_lock;
 libc_hidden_proto (__default_pthread_attr_lock)
 /* Called from __libc_freeres to deallocate the default attribute.  */
-extern void __default_pthread_attr_freeres (void);
+extern void __default_pthread_attr_freeres (void) attribute_hidden;
 
 /* Size and alignment of static TLS block.  */
 extern size_t __static_tls_size attribute_hidden;
@@ -314,9 +314,6 @@ __do_cancel (void)
    descriptor is still valid.  */
 extern void __free_tcb (struct pthread *pd) attribute_hidden;
 
-/* Free allocated stack.  */
-extern void __deallocate_stack (struct pthread *pd) attribute_hidden;
-
 /* Change the permissions of a thread stack.  Called from
    _dl_make_stacks_executable and pthread_create.  */
 int
@@ -679,8 +676,6 @@ void __nptl_setxid_sighandler (int sig, siginfo_t *si, void *ctx);
 libc_hidden_proto (__nptl_setxid_sighandler)
 extern int __nptl_setxid (struct xid_command *cmdp) attribute_hidden;
 
-extern void __nptl_stacks_freeres (void) attribute_hidden;
-
 extern void __wait_lookup_done (void) attribute_hidden;
 
 /* Allocates the extension space for ATTR.  Returns an error code on
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index d19456d..fcaf440 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -228,7 +228,7 @@ __free_tcb (struct pthread *pd)
       /* Queue the stack memory block for reuse and exit the process.  The
 	 kernel will signal via writing to the address returned by
 	 QUEUE-STACK when the stack is available.  */
-      __deallocate_stack (pd);
+      __nptl_deallocate_stack (pd);
     }
 }
 
@@ -711,7 +711,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
 	    futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
 
 	  /* Free the resources.  */
-	  __deallocate_stack (pd);
+	  __nptl_deallocate_stack (pd);
 	}
 
       /* We have to translate error codes.  */