From 14a40ffccd6163bbcd1d6f32b28a88ffe6149fc6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 19 Mar 2013 13:45:20 -0700 Subject: sched: replace PF_THREAD_BOUND with PF_NO_SETAFFINITY PF_THREAD_BOUND was originally used to mark kernel threads which were bound to a specific CPU using kthread_bind() and a task with the flag set allows cpus_allowed modifications only to itself. Workqueue is currently abusing it to prevent userland from meddling with cpus_allowed of workqueue workers. What we need is a flag to prevent userland from messing with cpus_allowed of certain kernel tasks. In kernel, anyone can (incorrectly) squash the flag, and, for worker-type usages, restricting cpus_allowed modification to the task itself doesn't provide meaningful extra proection as other tasks can inject work items to the task anyway. This patch replaces PF_THREAD_BOUND with PF_NO_SETAFFINITY. sched_setaffinity() checks the flag and return -EINVAL if set. set_cpus_allowed_ptr() is no longer affected by the flag. This will allow simplifying workqueue worker CPU affinity management. Signed-off-by: Tejun Heo Acked-by: Ingo Molnar Reviewed-by: Lai Jiangshan Cc: Peter Zijlstra Cc: Thomas Gleixner --- kernel/cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/cgroup.c') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a32f9432666c..3852d926322c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2224,11 +2224,11 @@ retry_find_task: tsk = tsk->group_leader; /* - * Workqueue threads may acquire PF_THREAD_BOUND and become + * Workqueue threads may acquire PF_NO_SETAFFINITY and become * trapped in a cpuset, or RT worker may be born in a cgroup * with no rt_runtime allocated. Just say no. */ - if (tsk == kthreadd_task || (tsk->flags & PF_THREAD_BOUND)) { + if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { ret = -EINVAL; rcu_read_unlock(); goto out_unlock_cgroup; -- cgit v1.2.1