Re: [PATCH v8 05/16] sched/core: Allow sched_setattr() to use the current policy
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-05-08 19:21:42
Also in:
linux-pm, lkml
On Tue, Apr 02, 2019 at 11:41:41AM +0100, Patrick Bellasi wrote:
quoted hunk ↗ jump to hunk
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
};
quoted hunk ↗ jump to hunk
/* Can be ORed in to make sure the process is reverted back to SCHED_NORMAL on fork */ #define SCHED_RESET_ON_FORK 0x40000000@@ -50,9 +52,11 @@ #define SCHED_FLAG_RESET_ON_FORK 0x01 #define SCHED_FLAG_RECLAIM 0x02 #define SCHED_FLAG_DL_OVERRUN 0x04 +#define SCHED_FLAG_KEEP_POLICY 0x08 #define SCHED_FLAG_ALL (SCHED_FLAG_RESET_ON_FORK | \ SCHED_FLAG_RECLAIM | \ - SCHED_FLAG_DL_OVERRUN) + SCHED_FLAG_DL_OVERRUN | \ + SCHED_FLAG_KEEP_POLICY) #endif /* _UAPI_LINUX_SCHED_H */diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d368ac26b8aa..20efb32e1a7e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c@@ -4907,8 +4907,17 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, if (retval) return retval; - if ((int)attr.sched_policy < 0) + /* + * A valid policy is always required from userspace, unless + * SCHED_FLAG_KEEP_POLICY is set and the current policy + * is enforced for this call. + */ + if (attr.sched_policy > SCHED_POLICY_MAX && + !(attr.sched_flags & SCHED_FLAG_KEEP_POLICY)) { return -EINVAL; + }
And given I just looked at those darn SCHED_* things, I now note the above does 'funny' things when passed: attr.policy=4.
+ if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY) + attr.sched_policy = SETPARAM_POLICY; rcu_read_lock(); retval = -ESRCH;