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authorTejun Heo <tj@kernel.org>2013-03-19 13:45:20 -0700
committerTejun Heo <tj@kernel.org>2013-03-19 13:45:20 -0700
commit14a40ffccd6163bbcd1d6f32b28a88ffe6149fc6 (patch)
treeeb61e5bf7b64c3e67f3e33fe6b07fde4ee1d4d43 /kernel/cpuset.c
parent2e109a2855bf6cf675a8b74dbd89b6492e8def42 (diff)
downloadblackbird-op-linux-14a40ffccd6163bbcd1d6f32b28a88ffe6149fc6.tar.gz
blackbird-op-linux-14a40ffccd6163bbcd1d6f32b28a88ffe6149fc6.zip
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 <tj@kernel.org> Acked-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4f9dfe43ecbd..f22e94792707 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1388,16 +1388,16 @@ static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
cgroup_taskset_for_each(task, cgrp, tset) {
/*
- * Kthreads bound to specific cpus cannot be moved to a new
- * cpuset; we cannot change their cpu affinity and
- * isolating such threads by their set of allowed nodes is
- * unnecessary. Thus, cpusets are not applicable for such
- * threads. This prevents checking for success of
- * set_cpus_allowed_ptr() on all attached tasks before
- * cpus_allowed may be changed.
+ * Kthreads which disallow setaffinity shouldn't be moved
+ * to a new cpuset; we don't want to change their cpu
+ * affinity and isolating such threads by their set of
+ * allowed nodes is unnecessary. Thus, cpusets are not
+ * applicable for such threads. This prevents checking for
+ * success of set_cpus_allowed_ptr() on all attached tasks
+ * before cpus_allowed may be changed.
*/
ret = -EINVAL;
- if (task->flags & PF_THREAD_BOUND)
+ if (task->flags & PF_NO_SETAFFINITY)
goto out_unlock;
ret = security_task_setscheduler(task);
if (ret)
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