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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/sched/core.c
parent2e109a2855bf6cf675a8b74dbd89b6492e8def42 (diff)
downloadlinaro-lsk-14a40ffccd6163bbcd1d6f32b28a88ffe6149fc6.tar.gz
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/sched/core.c')
-rw-r--r--kernel/sched/core.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7f12624a393..23606ee961b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4126,6 +4126,10 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
get_task_struct(p);
rcu_read_unlock();
+ if (p->flags & PF_NO_SETAFFINITY) {
+ retval = -EINVAL;
+ goto out_put_task;
+ }
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_put_task;
@@ -4773,11 +4777,6 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
goto out;
}
- if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) {
- ret = -EINVAL;
- goto out;
- }
-
do_set_cpus_allowed(p, new_mask);
/* Can the task run on the task's current CPU? If so, we're done */