[PATCH RT 08/19] kernel/hotplug: restore original cpu mask oncpu/down

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 kernel/cpu.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 22063f3..16ec791 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -563,6 +563,7 @@ 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;
@@ -573,6 +574,12 @@ 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);
@@ -581,7 +588,8 @@ 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();
@@ -639,6 +647,9 @@ 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;
 }
 
-- 
1.7.10.4


--
To unsubscribe from this list: send the line "unsubscribe stable-rt" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux USB Development]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux