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, 110 insertions, 0 deletions

diff --git a/nptl/pthread_setattr_default_np.c b/nptl/pthread_setattr_default_np.c
new file mode 100644
index 0000000000..e0b5239612
--- /dev/null
+++ b/nptl/pthread_setattr_default_np.c
@@ -0,0 +1,110 @@
+/* Set the default attributes to be used by pthread_create in the process.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <pthreadP.h>
+#include <assert.h>
+
+int
+pthread_setattr_default_np (const pthread_attr_t *in)
+{
+  const struct pthread_attr *real_in;
+  struct pthread_attr attrs;
+  int ret;
+
+  assert (sizeof (*in) >= sizeof (struct pthread_attr));
+  real_in = (struct pthread_attr *) in;
+
+  /* Catch invalid values.  */
+  int policy = real_in->schedpolicy;
+  ret = check_sched_policy_attr (policy);
+  if (ret)
+    return ret;
+
+  const struct sched_param *param = &real_in->schedparam;
+  if (param->sched_priority > 0)
+    {
+      ret = check_sched_priority_attr (param->sched_priority, policy);
+      if (ret)
+	return ret;
+    }
+
+  ret = check_cpuset_attr (real_in->cpuset, real_in->cpusetsize);
+  if (ret)
+    return ret;
+
+  /* stacksize == 0 is fine.  It means that we don't change the current
+     value.  */
+  if (real_in->stacksize != 0)
+    {
+      ret = check_stacksize_attr (real_in->stacksize);
+      if (ret)
+	return ret;
+    }
+
+  /* Having a default stack address is wrong.  */
+  if (real_in->flags & ATTR_FLAG_STACKADDR)
+    return EINVAL;
+
+  attrs = *real_in;
+
+  /* Now take the lock because we start writing into
+     __default_pthread_attr.  */
+  lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
+
+  /* Free the cpuset if the input is 0.  Otherwise copy in the cpuset
+     contents.  */
+  size_t cpusetsize = attrs.cpusetsize;
+  if (cpusetsize == 0)
+    {
+      free (__default_pthread_attr.cpuset);
+      __default_pthread_attr.cpuset = NULL;
+    }
+  else if (cpusetsize == __default_pthread_attr.cpusetsize)
+    {
+      attrs.cpuset = __default_pthread_attr.cpuset;
+      memcpy (attrs.cpuset, real_in->cpuset, cpusetsize);
+    }
+  else
+    {
+      /* This may look wrong at first sight, but it isn't.  We're freeing
+	 __default_pthread_attr.cpuset and allocating to attrs.cpuset because
+	 we'll copy over all of attr to __default_pthread_attr later.  */
+      cpu_set_t *newp = realloc (__default_pthread_attr.cpuset,
+				 cpusetsize);
+
+      if (newp == NULL)
+	{
+	  ret = ENOMEM;
+	  goto out;
+	}
+
+      attrs.cpuset = newp;
+      memcpy (attrs.cpuset, real_in->cpuset, cpusetsize);
+    }
+
+  /* We don't want to accidentally set the default stacksize to zero.  */
+  if (attrs.stacksize == 0)
+    attrs.stacksize = __default_pthread_attr.stacksize;
+  __default_pthread_attr = attrs;
+
+ out:
+  lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
+  return ret;
+}