On Thu, May 09, 2019 at 10:18:07AM +0100, Patrick Bellasi wrote:

On 08-May 21:21, Peter Zijlstra wrote:

quoted

On Tue, Apr 02, 2019 at 11:41:41AM +0100, Patrick Bellasi wrote:

quoted

diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index 22627f80063e..075c610adf45 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h

@@ -40,6 +40,8 @@
 /* SCHED_ISO: reserved but not implemented yet */
 #define SCHED_IDLE		5
 #define SCHED_DEADLINE		6
+/* Must be the last entry: used to sanity check attr.policy values */
+#define SCHED_POLICY_MAX	SCHED_DEADLINE

This is a wee bit sad to put in a uapi header; but yeah, where else :/

Another option would be something like:

enum {
	SCHED_NORMAL = 0,
	SCHED_FIFO = 1,
	SCHED_RR = 2,
	SCHED_BATCH = 3,
	/* SCHED_ISO = 4, reserved */
	SCHED_IDLE = 5,
	SCHED_DEADLINE = 6,
	SCHED_POLICY_NR
};

I just wanted to minimize the changes by keeping the same structure...
If you prefer the above I can add a refactoring patch just to update
existing definitions before adding this patch...

Right; I've no idea really. The thing that started all this was adding
that define to UAPI. Maybe we can do without it and instead put in a
comment to check sched_setattr() any time we add a new policy and just
hard code the thing.