Re: [PATCH] md:Fix name of raid thread when raid takeovered

[NeilBrown <neilb@suse.de>]

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On Thu, 31 May 2012 15:41:22 +0800 "majianpeng" <majianpeng@gmail.com> wrote:

> When raid takeovered, it used old personality to set task->comm.
> 
> Signed-off-by: majianpeng <majianpeng@gmail.com>
> ---
>  drivers/md/md.c |   15 +++++++++++++++
>  1 files changed, 15 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 1c2f904..93e20ea 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -32,6 +32,7 @@
>     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>  */
>  
> +#include <linux/sched.h>
>  #include <linux/kthread.h>
>  #include <linux/blkdev.h>
>  #include <linux/sysctl.h>
> @@ -3513,6 +3514,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
>  	long level;
>  	void *priv;
>  	struct md_rdev *rdev;
> +	char *tmp;
>  
>  	if (mddev->pers == NULL) {
>  		if (len == 0)
> @@ -3674,6 +3676,19 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
>  		del_timer_sync(&mddev->safemode_timer);
>  	}
>  	pers->run(mddev);
> +	/*
> +	 * when raid takeover using old personality,so mddev->thread->tsk
> +	 * name is wrong.
> +	 * if kzalloc error, only using wrong name.
> +	 */
> +	len = strlen(mdname(mddev)) + strlen(mddev->pers->name);
> +	tmp = kzalloc(len + 2, GFP_KERNEL);
> +	if (tmp) {
> +		sprintf(tmp, "%s_%s", mdname(mddev), mddev->pers->name);
> +		set_task_comm(mddev->thread->tsk, tmp);
> +		kfree(tmp);
> +	}
> +
>  	set_bit(MD_CHANGE_DEVS, &mddev->flags);
>  	mddev_resume(mddev);
>  	sysfs_notify(&mddev->kobj, NULL, "level");

Thanks.  However:

 1/ as a task name is limited to TASK_COMM_LEN, there is little point using
    kzalloc.  Just declare a local variable of that size.
 2/ No all levels have a thread.  You should check that mddev->thread is not
    NULL.

If you resubmit with those fixes I'll apply the patch.

Thanks,
NeilBrown


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