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Subject[PATCH 10/16] sched: add resource limits for -deadline tasks.
Date
From: Dario Faggioli <raistlin@linux.it>

Add resource limits for non-root tasks in using the SCHED_DEADLINE
policy, very similarly to what already exists for RT policies.

In fact, this patch:
- adds the resource limit RLIMIT_DLDLINE, which is the minimum value
a user task can use as its own deadline;
- adds the resource limit RLIMIT_DLRTIME, which is the maximum value
a user task can use as it own runtime.

Notice that to exploit these, a modified version of the ulimit
utility and a modified resource.h header file are needed. They
both will be available on the website of the project.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
---
include/asm-generic/resource.h | 7 ++++++-
kernel/sched.c | 25 +++++++++++++++++++++++++
2 files changed, 31 insertions(+), 1 deletions(-)

diff --git a/include/asm-generic/resource.h b/include/asm-generic/resource.h
index 61fa862..a682848 100644
--- a/include/asm-generic/resource.h
+++ b/include/asm-generic/resource.h
@@ -45,7 +45,10 @@
0-39 for nice level 19 .. -20 */
#define RLIMIT_RTPRIO 14 /* maximum realtime priority */
#define RLIMIT_RTTIME 15 /* timeout for RT tasks in us */
-#define RLIM_NLIMITS 16
+
+#define RLIMIT_DLDLINE 16 /* minimum deadline in us */
+#define RLIMIT_DLRTIME 17 /* maximum runtime in us */
+#define RLIM_NLIMITS 18

/*
* SuS says limits have to be unsigned.
@@ -87,6 +90,8 @@
[RLIMIT_NICE] = { 0, 0 }, \
[RLIMIT_RTPRIO] = { 0, 0 }, \
[RLIMIT_RTTIME] = { RLIM_INFINITY, RLIM_INFINITY }, \
+ [RLIMIT_DLDLINE] = { ULONG_MAX, ULONG_MAX }, \
+ [RLIMIT_DLRTIME] = { 0, 0 }, \
}

#endif /* __KERNEL__ */
diff --git a/kernel/sched.c b/kernel/sched.c
index ea4787a..92d5e26 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5593,6 +5593,31 @@ recheck:
* Allow unprivileged RT tasks to decrease priority:
*/
if (user && !capable(CAP_SYS_NICE)) {
+ if (dl_policy(policy)) {
+ u64 rlim_dline, rlim_rtime;
+ u64 dline, rtime;
+
+ if (!lock_task_sighand(p, &flags))
+ return -ESRCH;
+ rlim_dline = p->signal->rlim[RLIMIT_DLDLINE].rlim_cur;
+ rlim_rtime = p->signal->rlim[RLIMIT_DLRTIME].rlim_cur;
+ unlock_task_sighand(p, &flags);
+
+ /* can't set/change -deadline policy */
+ if (policy != p->policy && !rlim_rtime)
+ return -EPERM;
+
+ /* can't decrease the deadline */
+ rlim_dline *= NSEC_PER_USEC;
+ dline = param->sched_deadline;
+ if (dline < p->dl.dl_deadline && dline < rlim_dline)
+ return -EPERM;
+ /* can't increase the runtime */
+ rlim_rtime *= NSEC_PER_USEC;
+ rtime = param->sched_runtime;
+ if (rtime > p->dl.dl_runtime && rtime > rlim_rtime)
+ return -EPERM;
+ }
if (rt_policy(policy)) {
unsigned long rlim_rtprio =
task_rlimit(p, RLIMIT_RTPRIO);
--
1.7.5.4


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