sched: Add 'flags' argument to sched_{set,get}attr() syscalls

Because of a recent syscall design debate; its deemed appropriate for
each syscall to have a flags argument for future extension; without
immediately requiring new syscalls.

Cc: juri.lelli@gmail.com
Cc: Ingo Molnar <mingo@redhat.com>
Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140214161929.GL27965@twins.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 10 insertions, 7 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 40ed9e9a77e5..a747a77ea584 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -281,13 +281,15 @@ asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
 asmlinkage long sys_sched_setparam(pid_t pid,
                                         struct sched_param __user *param);
 asmlinkage long sys_sched_setattr(pid_t pid,
-                                        struct sched_attr __user *attr);
+                                        struct sched_attr __user *attr,
+                                        unsigned int flags);
 asmlinkage long sys_sched_getscheduler(pid_t pid);
 asmlinkage long sys_sched_getparam(pid_t pid,
                                         struct sched_param __user *param);
 asmlinkage long sys_sched_getattr(pid_t pid,
                                         struct sched_attr __user *attr,
-                                        unsigned int size);
+                                        unsigned int size,
+                                        unsigned int flags);
 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
                                         unsigned long __user *user_mask_ptr);
 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a6e7470166c7..6edbef296ece 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3661,13 +3661,14 @@ SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
  * @pid: the pid in question.
  * @uattr: structure containing the extended parameters.
  */
-SYSCALL_DEFINE2(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr)
+SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
+                               unsigned int, flags)
 {
         struct sched_attr attr;
         struct task_struct *p;
         int retval;
 
-        if (!uattr || pid < 0)
+        if (!uattr || pid < 0 || flags)
                 return -EINVAL;
 
         if (sched_copy_attr(uattr, &attr))
@@ -3804,8 +3805,8 @@ err_size:
  * @uattr: structure containing the extended parameters.
  * @size: sizeof(attr) for fwd/bwd comp.
  */
-SYSCALL_DEFINE3(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
-                unsigned int, size)
+SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
+                unsigned int, size, unsigned int, flags)
 {
         struct sched_attr attr = {
                 .size = sizeof(struct sched_attr),
@@ -3814,7 +3815,7 @@ SYSCALL_DEFINE3(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
         int retval;
 
         if (!uattr || pid < 0 || size > PAGE_SIZE ||
-            size < SCHED_ATTR_SIZE_VER0)
+            size < SCHED_ATTR_SIZE_VER0 || flags)
                 return -EINVAL;
 
         rcu_read_lock();