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kernel/hotplug: restore original cpu mask oncpu/down 

If a task which is allowed to run only on CPU X puts CPU Y down then it
will be allowed on all CPUs but the on CPU Y after it comes back from
kernel. This patch ensures that we don't lose the initial setting unless
the CPU the task is running is going down.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
This commit is contained in:
Sebastian Andrzej Siewior 2013-06-14 17:16:35 +02:00 committed by Alibek Omarov
parent 869f5656ff
commit 925c8d77e6
1 changed files with 12 additions and 1 deletions
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13
kernel/cpu.c
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@ -573,6 +573,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
.hcpu = hcpu,
};
cpumask_var_t cpumask;
cpumask_var_t cpumask_org;
if (num_online_cpus() == 1)
return -EBUSY;
@ -583,6 +584,12 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
/* Move the downtaker off the unplug cpu */
if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
return -ENOMEM;
if (!alloc_cpumask_var(&cpumask_org, GFP_KERNEL)) {
free_cpumask_var(cpumask);
return -ENOMEM;
}
cpumask_copy(cpumask_org, tsk_cpus_allowed(current));
cpumask_andnot(cpumask, cpu_online_mask, cpumask_of(cpu));
set_cpus_allowed_ptr(current, cpumask);
free_cpumask_var(cpumask);
@ -591,7 +598,8 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
if (mycpu == cpu) {
printk(KERN_ERR "Yuck! Still on unplug CPU\n!");
migrate_enable();
return -EBUSY;
err = -EBUSY;
goto restore_cpus;
}
cpu_hotplug_begin();
@ -669,6 +677,9 @@ out_cancel:
cpu_hotplug_done();
if (!err)
cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
restore_cpus:
set_cpus_allowed_ptr(current, cpumask_org);
free_cpumask_var(cpumask_org);
return err;
}