| From 4c6df3d78817c20a147c0291f6600d002c0910d3 Mon Sep 17 00:00:00 2001 |
| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Fri, 14 Jun 2013 17:16:35 +0200 |
| Subject: [PATCH] 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> |
| --- |
| kernel/cpu.c | 13 ++++++++++++- |
| 1 file changed, 12 insertions(+), 1 deletion(-) |
| |
| --- a/kernel/cpu.c |
| +++ b/kernel/cpu.c |
| @@ -568,6 +568,7 @@ static int __ref _cpu_down(unsigned int |
| .hcpu = hcpu, |
| }; |
| cpumask_var_t cpumask; |
| + cpumask_var_t cpumask_org; |
| |
| if (num_online_cpus() == 1) |
| return -EBUSY; |
| @@ -578,6 +579,12 @@ static int __ref _cpu_down(unsigned int |
| /* 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); |
| @@ -586,7 +593,8 @@ static int __ref _cpu_down(unsigned int |
| if (mycpu == cpu) { |
| printk(KERN_ERR "Yuck! Still on unplug CPU\n!"); |
| migrate_enable(); |
| - return -EBUSY; |
| + err = -EBUSY; |
| + goto restore_cpus; |
| } |
| |
| cpu_hotplug_begin(); |
| @@ -645,6 +653,9 @@ 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; |
| } |
| |