Commit-ID: 1d6362fa0cfc8c7b243fa92924429d826599e691 Gitweb: https://git.kernel.org/tip/1d6362fa0cfc8c7b243fa92924429d826599e691 Author: Patrick Bellasi <patrick.bellasi@xxxxxxx> AuthorDate: Fri, 21 Jun 2019 09:42:06 +0100 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Mon, 24 Jun 2019 19:23:46 +0200 sched/core: Allow sched_setattr() to use the current policy The sched_setattr() syscall mandates that a policy is always specified. This requires to always know which policy a task will have when attributes are configured and this makes it impossible to add more generic task attributes valid across different scheduling policies. Reading the policy before setting generic tasks attributes is racy since we cannot be sure it is not changed concurrently. Introduce the required support to change generic task attributes without affecting the current task policy. This is done by adding an attribute flag (SCHED_FLAG_KEEP_POLICY) to enforce the usage of the current policy. Add support for the SETPARAM_POLICY policy, which is already used by the sched_setparam() POSIX syscall, to the sched_setattr() non-POSIX syscall. Signed-off-by: Patrick Bellasi <patrick.bellasi@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Alessio Balsini <balsini@xxxxxxxxxxx> Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx> Cc: Joel Fernandes <joelaf@xxxxxxxxxx> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Morten Rasmussen <morten.rasmussen@xxxxxxx> Cc: Paul Turner <pjt@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Quentin Perret <quentin.perret@xxxxxxx> Cc: Rafael J . Wysocki <rafael.j.wysocki@xxxxxxxxx> Cc: Steve Muckle <smuckle@xxxxxxxxxx> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Todd Kjos <tkjos@xxxxxxxxxx> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20190621084217.8167-6-patrick.bellasi@xxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- include/uapi/linux/sched.h | 4 +++- kernel/sched/core.c | 2 ++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h index ed4ee170bee2..58b2368d3634 100644 --- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -51,9 +51,11 @@ #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 b74de86b68c7..6d519f3f9789 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4897,6 +4897,8 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, if ((int)attr.sched_policy < 0) return -EINVAL; + if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY) + attr.sched_policy = SETPARAM_POLICY; rcu_read_lock(); retval = -ESRCH;
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