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From: Tejun Heo on 1 Jun 2010 05:40
Apply the cpumask and cgroup of the initializing task to the created
vhost worker.

Based on Sridhar Samudrala's patch. Li Zefan spotted a bug in error
path (twice), fixed (twice).

Signed-off-by: Tejun Heo <tj(a)kernel.org>
Cc: Michael S. Tsirkin <mst(a)redhat.com>
Cc: Sridhar Samudrala <samudrala.sridhar(a)gmail.com>
Cc: Li Zefan <lizf(a)cn.fujitsu.com>
---
drivers/vhost/vhost.c | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)

Index: work/drivers/vhost/vhost.c
===================================================================
--- work.orig/drivers/vhost/vhost.c
+++ work/drivers/vhost/vhost.c
@@ -23,6 +23,7 @@
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/kthread.h>
+#include <linux/cgroup.h>

#include <linux/net.h>
#include <linux/if_packet.h>
@@ -187,11 +188,29 @@ long vhost_dev_init(struct vhost_dev *de
struct vhost_virtqueue *vqs, int nvqs)
{
struct task_struct *worker;
- int i;
+ cpumask_var_t mask;
+ int i, ret = -ENOMEM;
+
+ if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+ goto out_free_mask;

worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
- if (IS_ERR(worker))
- return PTR_ERR(worker);
+ if (IS_ERR(worker)) {
+ ret = PTR_ERR(worker);
+ goto out_free_mask;
+ }
+
+ ret = sched_getaffinity(current->pid, mask);
+ if (ret)
+ goto out_stop_worker;
+
+ ret = sched_setaffinity(worker->pid, mask);
+ if (ret)
+ goto out_stop_worker;
+
+ ret = cgroup_attach_task_current_cg(worker);
+ if (ret)
+ goto out_stop_worker;

dev->vqs = vqs;
dev->nvqs = nvqs;
@@ -214,7 +233,14 @@ long vhost_dev_init(struct vhost_dev *de
}

wake_up_process(worker); /* avoid contributing to loadavg */
- return 0;
+ ret = 0;
+ goto out_free_mask;
+
+out_stop_worker:
+ kthread_stop(worker);
+out_free_mask:
+ free_cpumask_var(mask);
+ return ret;
}

/* Caller should have device mutex */
--
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Prev: [PATCH 2/3] cgroups: Add an API to attach a task to current task's cgroup
Next: amd iommu fixes for 2.6.35-rc1