sched: Fix sched_setparam() policy == -1 logic

[platform/adaptation/renesas_rcar/renesas_kernel.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6edbef2..677ebad 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1322,7 +1322,7 @@ out:
                 * leave kernel.
                 */
                if (p->mm && printk_ratelimit()) {
-                       printk_sched("process %d (%s) no longer affine to cpu%d\n",
+                       printk_deferred("process %d (%s) no longer affine to cpu%d\n",
                                        task_pid_nr(p), p->comm, cpu);
                }
        }
@@ -3242,17 +3242,40 @@ __getparam_dl(struct task_struct *p, struct sched_attr *attr)
  * We ask for the deadline not being zero, and greater or equal
  * than the runtime, as well as the period of being zero or
  * greater than deadline. Furthermore, we have to be sure that
- * user parameters are above the internal resolution (1us); we
- * check sched_runtime only since it is always the smaller one.
+ * user parameters are above the internal resolution of 1us (we
+ * check sched_runtime only since it is always the smaller one) and
+ * below 2^63 ns (we have to check both sched_deadline and
+ * sched_period, as the latter can be zero).
  */
 static bool
 __checkparam_dl(const struct sched_attr *attr)
 {
-       return attr && attr->sched_deadline != 0 &&
-               (attr->sched_period == 0 ||
-               (s64)(attr->sched_period   - attr->sched_deadline) >= 0) &&
-               (s64)(attr->sched_deadline - attr->sched_runtime ) >= 0  &&
-               attr->sched_runtime >= (2 << (DL_SCALE - 1));
+       /* deadline != 0 */
+       if (attr->sched_deadline == 0)
+               return false;
+
+       /*
+        * Since we truncate DL_SCALE bits, make sure we're at least
+        * that big.
+        */
+       if (attr->sched_runtime < (1ULL << DL_SCALE))
+               return false;
+
+       /*
+        * Since we use the MSB for wrap-around and sign issues, make
+        * sure it's not set (mind that period can be equal to zero).
+        */
+       if (attr->sched_deadline & (1ULL << 63) ||
+           attr->sched_period & (1ULL << 63))
+               return false;
+
+       /* runtime <= deadline <= period (if period != 0) */
+       if ((attr->sched_period != 0 &&
+            attr->sched_period < attr->sched_deadline) ||
+           attr->sched_deadline < attr->sched_runtime)
+               return false;
+
+       return true;
 }
 
 /*
@@ -3338,6 +3361,15 @@ recheck:
                                return -EPERM;
                }
 
+                /*
+                 * Can't set/change SCHED_DEADLINE policy at all for now
+                 * (safest behavior); in the future we would like to allow
+                 * unprivileged DL tasks to increase their relative deadline
+                 * or reduce their runtime (both ways reducing utilization)
+                 */
+               if (dl_policy(policy))
+                       return -EPERM;
+
                /*
                 * Treat SCHED_IDLE as nice 20. Only allow a switch to
                 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
@@ -3479,9 +3511,10 @@ static int _sched_setscheduler(struct task_struct *p, int policy,
        };
 
        /*
-        * Fixup the legacy SCHED_RESET_ON_FORK hack
+        * Fixup the legacy SCHED_RESET_ON_FORK hack, except if
+        * the policy=-1 was passed by sched_setparam().
         */
-       if (policy & SCHED_RESET_ON_FORK) {
+       if ((policy != -1) && (policy & SCHED_RESET_ON_FORK)) {
                attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
                policy &= ~SCHED_RESET_ON_FORK;
                attr.sched_policy = policy;
@@ -3671,8 +3704,12 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
        if (!uattr || pid < 0 || flags)
                return -EINVAL;
 
-       if (sched_copy_attr(uattr, &attr))
-               return -EFAULT;
+       retval = sched_copy_attr(uattr, &attr);
+       if (retval)
+               return retval;
+
+       if ((int)attr.sched_policy < 0)
+               return -EINVAL;
 
        rcu_read_lock();
        retval = -ESRCH;
@@ -3722,7 +3759,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
  */
 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
 {
-       struct sched_param lp;
+       struct sched_param lp = { .sched_priority = 0 };
        struct task_struct *p;
        int retval;
 
@@ -3739,11 +3776,8 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
        if (retval)
                goto out_unlock;
 
-       if (task_has_dl_policy(p)) {
-               retval = -EINVAL;
-               goto out_unlock;
-       }
-       lp.sched_priority = p->rt_priority;
+       if (task_has_rt_policy(p))
+               lp.sched_priority = p->rt_priority;
        rcu_read_unlock();
 
        /*
@@ -5042,7 +5076,6 @@ static int sched_cpu_active(struct notifier_block *nfb,
                                      unsigned long action, void *hcpu)
 {
        switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_STARTING:
        case CPU_DOWN_FAILED:
                set_cpu_active((long)hcpu, true);
                return NOTIFY_OK;