git.maemo.org Git - kernel-bfs/blob - kernel-power-2.6.28/debian/patches/sched_reset_on_fork.diff

   1 Index: kernel-2.6.28/include/linux/sched.h
   2 ===================================================================
   3 --- kernel-2.6.28.orig/include/linux/sched.h
   4 +++ kernel-2.6.28/include/linux/sched.h
   5 @@ -45,6 +45,9 @@
   6  #define SCHED_RANGE(policy)    ((policy) <= SCHED_MAX)
   7  #endif
   8
   9 +/* Can be ORed in to make sure the process is reverted back to SCHED_NORMAL on fork */
  10 +#define SCHED_RESET_ON_FORK     0x40000000
  11 +
  12  #ifdef __KERNEL__
  13
  14  struct sched_param {
  15 @@ -1174,6 +1177,10 @@ struct task_struct {
  16         /* ??? */
  17         unsigned int personality;
  18         unsigned did_exec:1;
  19 +
  20 +       /* Revert to default priority/policy when forking */
  21 +       unsigned sched_reset_on_fork:1;
  22 +
  23         pid_t pid;
  24         pid_t tgid;
  25
  26 Index: kernel-2.6.28/kernel/sched_bfs.c
  27 ===================================================================
  28 --- kernel-2.6.28.orig/kernel/sched_bfs.c
  29 +++ kernel-2.6.28/kernel/sched_bfs.c
  30 @@ -1356,6 +1356,27 @@ void sched_fork(struct task_struct *p, i
  31         p->sched_time = p->stime_pc = p->utime_pc = 0;
  32
  33         /*
  34 +        * Revert to default priority/policy on fork if requested.
  35 +        */
  36 +       if (unlikely(p->sched_reset_on_fork)) {
  37 +               if (p->policy == SCHED_FIFO || p->policy == SCHED_RR) {
  38 +                       p->policy = SCHED_NORMAL;
  39 +                       p->normal_prio = normal_prio(p);
  40 +               }
  41 +
  42 +               if (PRIO_TO_NICE(p->static_prio) < 0) {
  43 +                       p->static_prio = NICE_TO_PRIO(0);
  44 +                       p->normal_prio = p->static_prio;
  45 +               }
  46 +
  47 +               /*
  48 +                * We don't need the reset flag anymore after the fork. It has
  49 +                * fulfilled its duty:
  50 +                */
  51 +               p->sched_reset_on_fork = 0;
  52 +       }
  53 +
  54 +       /*
  55          * Make sure we do not leak PI boosting priority to the child:
  56          */
  57         p->prio = current->normal_prio;
  58 @@ -3121,6 +3142,7 @@ static int __sched_setscheduler(struct t
  59         struct sched_param zero_param = { .sched_priority = 0 };
  60         int queued, retval, oldpolicy = -1;
  61         unsigned long flags, rlim_rtprio = 0;
  62 +       int reset_on_fork;
  63         struct rq *rq;
  64
  65         /* may grab non-irq protected spin_locks */
  66 @@ -3145,10 +3167,17 @@ static int __sched_setscheduler(struct t
  67         }
  68  recheck:
  69         /* double check policy once rq lock held */
  70 -       if (policy < 0)
  71 +       if (policy < 0) {
  72 +               reset_on_fork = p->sched_reset_on_fork;
  73                 policy = oldpolicy = p->policy;
  74 -       else if (!SCHED_RANGE(policy))
  75 -               return -EINVAL;
  76 +       } else {
  77 +               reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
  78 +               policy &= ~SCHED_RESET_ON_FORK;
  79 +
  80 +               if (!SCHED_RANGE(policy))
  81 +                       return -EINVAL;
  82 +       }
  83 +
  84         /*
  85          * Valid priorities for SCHED_FIFO and SCHED_RR are
  86          * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
  87 @@ -3211,6 +3240,10 @@ recheck:
  88                 if ((current->euid != p->euid) &&
  89                     (current->euid != p->uid))
  90                         return -EPERM;
  91 +
  92 +               /* Normal users shall not reset the sched_reset_on_fork flag */
  93 +               if (p->sched_reset_on_fork && !reset_on_fork)
  94 +                       return -EPERM;
  95         }
  96
  97         retval = security_task_setscheduler(p, policy, param);
  98 @@ -3234,6 +3267,8 @@ recheck:
  99                 goto recheck;
 100         }
 101         update_rq_clock(rq);
 102 +       p->sched_reset_on_fork = reset_on_fork;
 103 +
 104         queued = task_queued(p);
 105         if (queued)
 106                 dequeue_task(p);