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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-09-29 02:00:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-29 09:18:17 -0700 |
| commit | 8dc3e9099e01dfdd53f27f329c268eced03dfef6 (patch) | |
| tree | c4a88aeabd5726185bf65c75cc52145d9dc33e43 /kernel/sched.c | |
| parent | 57a6f51c4281aa3119975473c70dce0480d322bd (diff) | |
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[PATCH] sched_setscheduler: fix? policy checks
I am not sure this patch is correct: I can't understand what the current
code does, and I don't know what it was supposed to do.
The comment says:
* can't change policy, except between SCHED_NORMAL
* and SCHED_BATCH:
The code:
if (((policy != SCHED_NORMAL && p->policy != SCHED_BATCH) &&
(policy != SCHED_BATCH && p->policy != SCHED_NORMAL)) &&
But this is equivalent to:
if ( (is_rt_policy(policy) && has_rt_policy(p)) &&
which means something different. We can't _decrease_ the current
->rt_priority with such a check (if rlim[RLIMIT_RTPRIO] == 0).
Probably, it was supposed to be:
if ( !(policy == SCHED_NORMAL && p->policy == SCHED_BATCH) &&
!(policy == SCHED_BATCH && p->policy == SCHED_NORMAL)
this matches the comment, but strange: it doesn't allow to _drop_ the
realtime priority when rlim[RLIMIT_RTPRIO] == 0.
I think the right check would be:
/* can't set/change rt policy */
if (is_rt_policy(policy) &&
policy != p->policy &&
!rlim_rtprio)
return -EPERM;
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 38 |
1 files changed, 18 insertions, 20 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index c3c718aea61..155a33da7aa 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4116,27 +4116,25 @@ recheck: * Allow unprivileged RT tasks to decrease priority: */ if (!capable(CAP_SYS_NICE)) { - unsigned long rlim_rtprio; - unsigned long flags; - - if (!lock_task_sighand(p, &flags)) - return -ESRCH; - rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur; - unlock_task_sighand(p, &flags); + if (is_rt_policy(policy)) { + unsigned long rlim_rtprio; + unsigned long flags; + + if (!lock_task_sighand(p, &flags)) + return -ESRCH; + rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur; + unlock_task_sighand(p, &flags); + + /* can't set/change the rt policy */ + if (policy != p->policy && !rlim_rtprio) + return -EPERM; + + /* can't increase priority */ + if (param->sched_priority > p->rt_priority && + param->sched_priority > rlim_rtprio) + return -EPERM; + } - /* - * can't change policy, except between SCHED_NORMAL - * and SCHED_BATCH: - */ - if (((policy != SCHED_NORMAL && p->policy != SCHED_BATCH) && - (policy != SCHED_BATCH && p->policy != SCHED_NORMAL)) && - !rlim_rtprio) - return -EPERM; - /* can't increase priority */ - if (is_rt_policy(policy) && - param->sched_priority > p->rt_priority && - param->sched_priority > rlim_rtprio) - return -EPERM; /* can't change other user's priorities */ if ((current->euid != p->euid) && (current->euid != p->uid)) |