Remove CPU set size checking from affinity functions [BZ #19143]

With current kernel versions, the check does not reliably detect that
unavailable CPUs are requested, for these reasons:

(1) The kernel will silently ignore non-allowed CPUs, that is, CPUs
    which are physically present but disallowed for the thread
    based on system configuration.

(2) Similarly, CPU bits which lack an online CPU (possible CPUs)
    are ignored.

(3) The existing probing code assumes that the CPU mask size is a
    power of two and at least 1024.  Neither has it to be a power
    of two, nor is the minimum possible value 1024, so the value
    determined is often too large.  This means that the CPU set
    size check in glibc accepts CPU bits beyond the actual hard
    system limit.

(4) Future kernel versions may not even have a fixed CPU set size.

After the removal of the probing code, the kernel still returns
EINVAL if no CPU in the requested set remains which can run the
thread after the affinity change.

Applications which care about the exact affinity mask will have
to query it using sched_getaffinity after setting it.  Due to the
effects described above, this commit does not change this.

The new tests supersede tst-getcpu, which is removed.  This
addresses bug 19164 because the new tests allocate CPU sets
dynamically.

	* nptl/check-cpuset.h: Remove.
	* nptl/pthread_attr_setaffinity.c (__pthread_attr_setaffinity_new):
	Remove CPU set size check.
	* nptl/pthread_setattr_default_np.c (pthread_setattr_default_np):
	Likewise.
	* sysdeps/unix/sysv/linux/check-cpuset.h: Remove.
	* sysdeps/unix/sysv/linux/pthread_setaffinity.c
	(__kernel_cpumask_size, __determine_cpumask_size): Remove.
	(__pthread_setaffinity_new): Remove CPU set size check.
	* sysdeps/unix/sysv/linux/sched_setaffinity.c
	(__kernel_cpumask_size): Remove.
	(__sched_setaffinity_new): Remove CPU set size check.
	* manual/threads.texi (Default Thread Attributes): Remove stale
	reference to check_cpuset_attr, determine_cpumask_size in comment.
	* sysdeps/unix/sysv/linux/Makefile [$(subdir) == posix] (tests):
	Remove tst-getcpu.  Add tst-affinity, tst-affinity-pid.
	[$(subdir) == nptl] (tests): Add tst-thread-affinity-pthread,
	tst-thread-affinity-pthread2, tst-thread-affinity-sched.
	* sysdeps/unix/sysv/linux/tst-affinity.c: New file.
	* sysdeps/unix/sysv/linux/tst-affinity-pid.c: New file.
	* sysdeps/unix/sysv/linux/tst-skeleton-affinity.c: New skeleton test file.
	* sysdeps/unix/sysv/linux/tst-thread-affinity-sched.c: New file.
	* sysdeps/unix/sysv/linux/tst-thread-affinity-pthread.c: New file.
	* sysdeps/unix/sysv/linux/tst-thread-affinity-pthread2.c: New file.
	* sysdeps/unix/sysv/linux/tst-thread-skeleton-affinity.c: New
	skeleton test file.
	* sysdeps/unix/sysv/linux/tst-getcpu.c: Remove.  Superseded by
	tst-affinity-pid.

3 files changed, 0 insertions, 43 deletions

diff --git a/nptl/check-cpuset.h b/nptl/check-cpuset.h
deleted file mode 100644
index 315bdf2..0000000
--- a/nptl/check-cpuset.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Validate cpu_set_t values for NPTL.  Stub version.
-   Copyright (C) 2015 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>
-
-/* Returns 0 if CS and SZ are valid values for the cpuset and cpuset size
-   respectively.  Otherwise it returns an error number.  */
-static inline int
-check_cpuset_attr (const cpu_set_t *cs, const size_t sz)
-{
-  if (sz == 0)
-    return 0;
-
-  /* This means pthread_attr_setaffinity will return ENOSYS, which
-     is the right thing when the cpu_set_t features are not available.  */
-  return ENOSYS;
-}
diff --git a/nptl/pthread_attr_setaffinity.c b/nptl/pthread_attr_setaffinity.c
index 7a127b8..571835d 100644
--- a/nptl/pthread_attr_setaffinity.c
+++ b/nptl/pthread_attr_setaffinity.c
@@ -23,7 +23,6 @@
 #include <string.h>
 #include <pthreadP.h>
 #include <shlib-compat.h>
-#include <check-cpuset.h>
 
 
 int
@@ -43,11 +42,6 @@ __pthread_attr_setaffinity_new (pthread_attr_t *attr, size_t cpusetsize,
     }
   else
     {
-      int ret = check_cpuset_attr (cpuset, cpusetsize);
-
-      if (ret)
-        return ret;
-
       if (iattr->cpusetsize != cpusetsize)
 	{
 	  void *newp = (cpu_set_t *) realloc (iattr->cpuset, cpusetsize);
diff --git a/nptl/pthread_setattr_default_np.c b/nptl/pthread_setattr_default_np.c
index 457a467..1a661f1 100644
--- a/nptl/pthread_setattr_default_np.c
+++ b/nptl/pthread_setattr_default_np.c
@@ -21,7 +21,6 @@
 #include <pthreadP.h>
 #include <assert.h>
 #include <string.h>
-#include <check-cpuset.h>
 
 
 int
@@ -48,10 +47,6 @@ pthread_setattr_default_np (const pthread_attr_t *in)
 	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)