Tejun Heo wrote:
> Apply the cpumask and cgroup of the initializing task to the created
> vhost poller.
>
> Based on Sridhar Samudrala's patch.
>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Sridhar Samudrala <samudrala.sridhar@xxxxxxxxx>
> ---
> drivers/vhost/vhost.c | 36 +++++++++++++++++++++++++++++++-----
> 1 file changed, 31 insertions(+), 5 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>
> @@ -176,12 +177,30 @@ repeat:
> long vhost_dev_init(struct vhost_dev *dev,
> struct vhost_virtqueue *vqs, int nvqs)
> {
> - struct task_struct *poller;
> - int i;
> + struct task_struct *poller = NULL;
> + cpumask_var_t mask;
> + int i, ret = -ENOMEM;
> +
> + if (!alloc_cpumask_var(&mask, GFP_KERNEL))
> + goto out;
>
If we "goto out", we will end up calling kthread_stop(poller), but
seems kthread_stop() requires the task_struct pointer != NULL.
> poller = kthread_create(vhost_poller, dev, "vhost-%d", current->pid);
> - if (IS_ERR(poller))
> - return PTR_ERR(poller);
> + if (IS_ERR(poller)) {
> + ret = PTR_ERR(poller);
> + goto out;
> + }
> +
> + ret = sched_getaffinity(current->pid, mask);
> + if (ret)
> + goto out;
> +
> + ret = sched_setaffinity(poller->pid, mask);
> + if (ret)
> + goto out;
> +
> + ret = cgroup_attach_task_current_cg(poller);
> + if (ret)
> + goto out;
>
> dev->vqs = vqs;
> dev->nvqs = nvqs;
> @@ -202,7 +221,14 @@ long vhost_dev_init(struct vhost_dev *de
> vhost_poll_init(&dev->vqs[i].poll,
> dev->vqs[i].handle_kick, POLLIN, dev);
> }
> - return 0;
> +
> + wake_up_process(poller); /* avoid contributing to loadavg */
> + ret = 0;
> +out:
> + if (ret)
> + kthread_stop(poller);
> + free_cpumask_var(mask);
> + return ret;
> }
>
> /* Caller should have device mutex */
--
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