On Sat, 6 Oct 2007, Paul Jackson wrote:
> This isn't working for me.
>
> The key kernel routine for updating a tasks cpus_allowed
> cannot be called while holding a spinlock.
>
> But the above loop holds a spinlock, css_set_lock, between
> the cgroup_iter_start and the cgroup_iter_end.
>
> I end up generating complaints of:
> BUG: scheduling while atomic
> when I invoke the set_cpus_allowed() above.
>
> Should css_set_lock be a mutex? Locking changes like that
> can be risky.
>
It would probably be better to just save references to the tasks.
struct cgroup_iter it;
struct task_struct *p, **tasks;
int i = 0;
cgroup_iter_start(cs->css.cgroup, &it);
while ((p = cgroup_iter_next(cs->css.cgroup, &it))) {
get_task_struct(p);
tasks[i++] = p;
}
cgroup_iter_end(cs->css.cgroup, &it);
while (--i >= 0) {
set_cpus_allowed(tasks[i], cs->cpus_allowed);
put_task_struct(tasks[i]);
}
The getting and putting of the tasks will prevent them from exiting or
being deallocated prematurely. But this is also a critical section that
will need to be protected by some mutex so it doesn't race with other
set_cpus_allowed().
David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
