From 18586e721636527cb5177467fb17e2350615978a Mon Sep 17 00:00:00 2001 From: Andreas Steinmetz Date: Sat, 23 Jul 2005 13:42:04 +0200 Subject: [PATCH] Fix RLIMIT_RTPRIO breakage RLIMIT_RTPRIO is supposed to grant non privileged users the right to use SCHED_FIFO/SCHED_RR scheduling policies with priorites bounded by the RLIMIT_RTPRIO value via sched_setscheduler(). This is usually used by audio users. Unfortunately this is broken in 2.6.13rc3 as you can see in the excerpt from sched_setscheduler below: /* * Allow unprivileged RT tasks to decrease priority: */ if (!capable(CAP_SYS_NICE)) { /* can't change policy */ if (policy != p->policy) return -EPERM; After the above unconditional test which causes sched_setscheduler to fail with no regard to the RLIMIT_RTPRIO value the following check is made: /* can't increase priority */ if (policy != SCHED_NORMAL && param->sched_priority > p->rt_priority && param->sched_priority > p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) return -EPERM; Thus I do believe that the RLIMIT_RTPRIO value must be taken into account for the policy check, especially as the RLIMIT_RTPRIO limit is of no use without this change. The attached patch fixes this problem. Signed-off-by: Andreas Steinmetz Acked-by: Ingo Molnar Signed-off-by: Linus Torvalds --- kernel/sched.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index 4107db0dc091..a5fb654ea590 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3528,7 +3528,8 @@ recheck: */ if (!capable(CAP_SYS_NICE)) { /* can't change policy */ - if (policy != p->policy) + if (policy != p->policy && + !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) return -EPERM; /* can't increase priority */ if (policy != SCHED_NORMAL && -- cgit v1.2.2 From d46523ea32a79fbc8cd1237f9441f45cc3f02456 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 25 Jul 2005 16:28:39 -0400 Subject: [PATCH] fix MAX_USER_RT_PRIO and MAX_RT_PRIO Here's the patch again to fix the code to handle if the values between MAX_USER_RT_PRIO and MAX_RT_PRIO are different. Without this patch, an SMP system will crash if the values are different. Signed-off-by: Steven Rostedt Cc: Ingo Molnar Signed-off-by: Dean Nelson Signed-off-by: Linus Torvalds --- kernel/sched.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index a5fb654ea590..a646e4f36c41 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3486,7 +3486,7 @@ static void __setscheduler(struct task_struct *p, int policy, int prio) p->policy = policy; p->rt_priority = prio; if (policy != SCHED_NORMAL) - p->prio = MAX_USER_RT_PRIO-1 - p->rt_priority; + p->prio = MAX_RT_PRIO-1 - p->rt_priority; else p->prio = p->static_prio; } @@ -3518,7 +3518,8 @@ recheck: * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0. */ if (param->sched_priority < 0 || - param->sched_priority > MAX_USER_RT_PRIO-1) + (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || + (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) return -EINVAL; if ((policy == SCHED_NORMAL) != (param->sched_priority == 0)) return -EINVAL; -- cgit v1.2.2