Re: [PATCH roland/nptl] NPTL: Don't (re)validate sched_priority in pthread_create.

["Carlos O'Donell" <carlos at redhat dot com>]

On 11/19/2014 08:41 PM, Roland McGrath wrote:
> I've committed the change (after committing the new test and verifying it
> passes both before and after).  If you'd like to review the one change
> remaining on roland/nptl (freshly rebased) soon, that would be great.
> After a day or two, I'll take silence as assent. :-)

LGTM.

diff --git a/ChangeLog b/ChangeLog
index 6199b7e..e207ce4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2014-11-19  Roland McGrath  <roland@hack.frob.com>
 
+	* nptl/default-sched.h: New file.
+	* sysdeps/unix/sysv/linux/default-sched.h: New file.
+	* nptl/pthread_create.c: Include it.
+	(__pthread_create_2_1): Use collect_default_sched instead of making
+	Linux syscalls here directly.

OK.

+
+2014-11-19  Roland McGrath  <roland@hack.frob.com>
+
 	* nptl/pthread_create.c (__pthread_create_2_1): Don't try to validate
 	the sched_priority value here.  It was already checked when the user
 	called pthread_attr_setschedparam.
diff --git a/nptl/default-sched.h b/nptl/default-sched.h
new file mode 100644
index 0000000..fb33e7c
--- /dev/null
+++ b/nptl/default-sched.h
@@ -0,0 +1,35 @@
+/* Determine calling thread's scheduling parameters.  Stub version.
+   Copyright (C) 2014 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 Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#include <assert.h>
+
+/* This should fill in PD->schedpolicy if PD->flags does not contain
+   ATTR_FLAG_POLICY_SET, and set it; and PD->schedparam if PD->flags does
+   not contain ATTR_FLAG_SCHED_SET, and set it.  It won't be called at all
+   if both bits are already set.  */
+
+static void
+collect_default_sched (struct pthread *pd)
+{
+  assert ((pd->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0);
+
+  /* The generic/stub version is a no-op rather than just using the
+     __sched_getscheduler and __sched_getparam functions so that there
+     won't be stub warnings for those functions just because pthread_create
+     was called without actually calling those.  */
+}


OK.

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 1dd1b95..3d4b8cd 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -30,6 +30,7 @@
 #include <resolv.h>
 #include <kernel-features.h>
 #include <exit-thread.h>
+#include <default-sched.h>
 
 #include <shlib-compat.h>
 
@@ -593,26 +594,16 @@ __pthread_create_2_1 (newthread, attr, start_routine, arg)
   if (__builtin_expect ((iattr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0, 0)
       && (iattr->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0)
     {
-      INTERNAL_SYSCALL_DECL (scerr);
-
       /* Use the scheduling parameters the user provided.  */
       if (iattr->flags & ATTR_FLAG_POLICY_SET)
 	pd->schedpolicy = iattr->schedpolicy;
-      else if ((pd->flags & ATTR_FLAG_POLICY_SET) == 0)
-	{
-	  pd->schedpolicy = INTERNAL_SYSCALL (sched_getscheduler, scerr, 1, 0);
-	  pd->flags |= ATTR_FLAG_POLICY_SET;
-	}
-
       if (iattr->flags & ATTR_FLAG_SCHED_SET)
         /* The values were validated in pthread_attr_setschedparam.  */
-	memcpy (&pd->schedparam, &iattr->schedparam,
-		sizeof (struct sched_param));
-      else if ((pd->flags & ATTR_FLAG_SCHED_SET) == 0)
-	{
-	  INTERNAL_SYSCALL (sched_getparam, scerr, 2, 0, &pd->schedparam);
-	  pd->flags |= ATTR_FLAG_SCHED_SET;
-	}
+        pd->schedparam = iattr->schedparam;
+
+      if ((pd->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
+          != (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
+        collect_default_sched (pd);

OK, pd->flags will have been updated earlier and thus will either be set
here or it won't be and we call collect_default_sched.


     }
 
   /* Pass the descriptor to the caller.  */
diff --git a/sysdeps/unix/sysv/linux/default-sched.h b/sysdeps/unix/sysv/linux/default-sched.h
new file mode 100644
index 0000000..c25778f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/default-sched.h
@@ -0,0 +1,42 @@
+/* Determine calling thread's scheduling parameters.  Linux version.
+   Copyright (C) 2014 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 Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+/* This should fill in PD->schedpolicy if PD->flags does not contain
+   ATTR_FLAG_POLICY_SET, and set it; and PD->schedparam if PD->flags does
+   not contain ATTR_FLAG_SCHED_SET, and set it.  It won't be called at all
+   if both bits are already set.  */
+
+static void
+collect_default_sched (struct pthread *pd)
+{
+  INTERNAL_SYSCALL_DECL (scerr);
+
+  if ((pd->flags & ATTR_FLAG_POLICY_SET) == 0)
+    {
+      pd->schedpolicy = INTERNAL_SYSCALL (sched_getscheduler, scerr, 1, 0);
+      pd->flags |= ATTR_FLAG_POLICY_SET;
+    }
+
+  if ((pd->flags & ATTR_FLAG_SCHED_SET) == 0)
+    {
+      INTERNAL_SYSCALL (sched_getparam, scerr, 2, 0, &pd->schedparam);
+      pd->flags |= ATTR_FLAG_SCHED_SET;
+    }
+}

OK.

Cheers,
Carlos.