coreutils/coreutils-8.26-test-lock.patch

From 4f6cb65ce4d643aca0c6bf7db2e8b32c0d08eb89 Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Sat, 24 Dec 2016 18:21:59 +0100
Subject: [PATCH 1/2] lock test: Fix performance problem on multi-core
 machines.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* tests/test-lock.c (USE_VOLATILE): New macro.
(struct atomic_int): New type.
(init_atomic_int, get_atomic_int_value, set_atomic_int_value): New
functions.
(lock_checker_done, rwlock_checker_done, reclock_checker_done): Define
as 'struct atomic_int'.
(lock_checker_thread, test_lock, rwlock_checker_thread, test_rwlock,
reclock_checker_thread, test_recursive_lock): Use the new functions.
Reported by Eric Blake in
https://www.redhat.com/archives/libvir-list/2012-March/msg00854.html
and by Pádraig Brady in
http://lists.gnu.org/archive/html/bug-gnulib/2016-12/msg00117.html.

Upstream-commit: 480d374e596a0ee3fed168ab42cd84c313ad3c89
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
 gnulib-tests/test-lock.c | 79 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 67 insertions(+), 12 deletions(-)

diff --git a/gnulib-tests/test-lock.c b/gnulib-tests/test-lock.c
index cb734b4..aa6de27 100644
--- a/gnulib-tests/test-lock.c
+++ b/gnulib-tests/test-lock.c
@@ -50,6 +50,13 @@
    Uncomment this to see if the operating system has a fair scheduler.  */
 #define EXPLICIT_YIELD 1
 
+/* Whether to use 'volatile' on some variables that communicate information
+   between threads.  If set to 0, a lock is used to protect these variables.
+   If set to 1, 'volatile' is used; this is theoretically equivalent but can
+   lead to much slower execution (e.g. 30x slower total run time on a 40-core
+   machine.  */
+#define USE_VOLATILE 0
+
 /* Whether to print debugging messages.  */
 #define ENABLE_DEBUGGING 0
 
@@ -103,6 +110,51 @@
 # define yield()
 #endif
 
+#if USE_VOLATILE
+struct atomic_int {
+  volatile int value;
+};
+static void
+init_atomic_int (struct atomic_int *ai)
+{
+}
+static int
+get_atomic_int_value (struct atomic_int *ai)
+{
+  return ai->value;
+}
+static void
+set_atomic_int_value (struct atomic_int *ai, int new_value)
+{
+  ai->value = new_value;
+}
+#else
+struct atomic_int {
+  gl_lock_define (, lock)
+  int value;
+};
+static void
+init_atomic_int (struct atomic_int *ai)
+{
+  gl_lock_init (ai->lock);
+}
+static int
+get_atomic_int_value (struct atomic_int *ai)
+{
+  gl_lock_lock (ai->lock);
+  int ret = ai->value;
+  gl_lock_unlock (ai->lock);
+  return ret;
+}
+static void
+set_atomic_int_value (struct atomic_int *ai, int new_value)
+{
+  gl_lock_lock (ai->lock);
+  ai->value = new_value;
+  gl_lock_unlock (ai->lock);
+}
+#endif
+
 #define ACCOUNT_COUNT 4
 
 static int account[ACCOUNT_COUNT];
@@ -170,12 +222,12 @@ lock_mutator_thread (void *arg)
   return NULL;
 }
 
-static volatile int lock_checker_done;
+static struct atomic_int lock_checker_done;
 
 static void *
 lock_checker_thread (void *arg)
 {
-  while (!lock_checker_done)
+  while (get_atomic_int_value (&lock_checker_done) == 0)
     {
       dbgprintf ("Checker %p before check lock\n", gl_thread_self_pointer ());
       gl_lock_lock (my_lock);
@@ -200,7 +252,8 @@ test_lock (void)
   /* Initialization.  */
   for (i = 0; i < ACCOUNT_COUNT; i++)
     account[i] = 1000;
-  lock_checker_done = 0;
+  init_atomic_int (&lock_checker_done);
+  set_atomic_int_value (&lock_checker_done, 0);
 
   /* Spawn the threads.  */
   checkerthread = gl_thread_create (lock_checker_thread, NULL);
@@ -210,7 +263,7 @@ test_lock (void)
   /* Wait for the threads to terminate.  */
   for (i = 0; i < THREAD_COUNT; i++)
     gl_thread_join (threads[i], NULL);
-  lock_checker_done = 1;
+  set_atomic_int_value (&lock_checker_done, 1);
   gl_thread_join (checkerthread, NULL);
   check_accounts ();
 }
@@ -254,12 +307,12 @@ rwlock_mutator_thread (void *arg)
   return NULL;
 }
 
-static volatile int rwlock_checker_done;
+static struct atomic_int rwlock_checker_done;
 
 static void *
 rwlock_checker_thread (void *arg)
 {
-  while (!rwlock_checker_done)
+  while (get_atomic_int_value (&rwlock_checker_done) == 0)
     {
       dbgprintf ("Checker %p before check rdlock\n", gl_thread_self_pointer ());
       gl_rwlock_rdlock (my_rwlock);
@@ -284,7 +337,8 @@ test_rwlock (void)
   /* Initialization.  */
   for (i = 0; i < ACCOUNT_COUNT; i++)
     account[i] = 1000;
-  rwlock_checker_done = 0;
+  init_atomic_int (&rwlock_checker_done);
+  set_atomic_int_value (&rwlock_checker_done, 0);
 
   /* Spawn the threads.  */
   for (i = 0; i < THREAD_COUNT; i++)
@@ -295,7 +349,7 @@ test_rwlock (void)
   /* Wait for the threads to terminate.  */
   for (i = 0; i < THREAD_COUNT; i++)
     gl_thread_join (threads[i], NULL);
-  rwlock_checker_done = 1;
+  set_atomic_int_value (&rwlock_checker_done, 1);
   for (i = 0; i < THREAD_COUNT; i++)
     gl_thread_join (checkerthreads[i], NULL);
   check_accounts ();
@@ -356,12 +410,12 @@ reclock_mutator_thread (void *arg)
   return NULL;
 }
 
-static volatile int reclock_checker_done;
+static struct atomic_int reclock_checker_done;
 
 static void *
 reclock_checker_thread (void *arg)
 {
-  while (!reclock_checker_done)
+  while (get_atomic_int_value (&reclock_checker_done) == 0)
     {
       dbgprintf ("Checker %p before check lock\n", gl_thread_self_pointer ());
       gl_recursive_lock_lock (my_reclock);
@@ -386,7 +440,8 @@ test_recursive_lock (void)
   /* Initialization.  */
   for (i = 0; i < ACCOUNT_COUNT; i++)
     account[i] = 1000;
-  reclock_checker_done = 0;
+  init_atomic_int (&reclock_checker_done);
+  set_atomic_int_value (&reclock_checker_done, 0);
 
   /* Spawn the threads.  */
   checkerthread = gl_thread_create (reclock_checker_thread, NULL);
@@ -396,7 +451,7 @@ test_recursive_lock (void)
   /* Wait for the threads to terminate.  */
   for (i = 0; i < THREAD_COUNT; i++)
     gl_thread_join (threads[i], NULL);
-  reclock_checker_done = 1;
+  set_atomic_int_value (&reclock_checker_done, 1);
   gl_thread_join (checkerthread, NULL);
   check_accounts ();
 }
-- 
2.7.4


From 0d04ee8ddedb2bf33d64f148f246a3b7ec4fef21 Mon Sep 17 00:00:00 2001
From: Kamil Dudka <kdudka@redhat.com>
Date: Mon, 23 Jan 2017 12:35:41 +0100
Subject: [PATCH 2/2] test-lock: disable the rwlock test

It hangs indefinitely if the system rwlock implementation does not
prevent writer starvation (and glibc does not implement it).

Bug: http://www.mail-archive.com/bug-gnulib@gnu.org/msg33017.html
---
 gnulib-tests/test-lock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gnulib-tests/test-lock.c b/gnulib-tests/test-lock.c
index aa6de27..5af0a6c 100644
--- a/gnulib-tests/test-lock.c
+++ b/gnulib-tests/test-lock.c
@@ -42,7 +42,7 @@
    Uncomment some of these, to verify that all tests crash if no locking
    is enabled.  */
 #define DO_TEST_LOCK 1
-#define DO_TEST_RWLOCK 1
+#define DO_TEST_RWLOCK 0
 #define DO_TEST_RECURSIVE_LOCK 1
 #define DO_TEST_ONCE 1
 
-- 
2.7.4