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

[majianpeng <majianpeng@xxxxxxxxx>]

On Sun, 3 Jun 2012 20:49:05 -0700,neil wrote:
>On Thu, 31 May 2012 15:41:22 +0800 "majianpeng" <majianpeng@xxxxxxxxx> wrote:
>
>> When raid takeovered, it used old personality to set task->comm.
>> 
>> Signed-off-by: majianpeng <majianpeng@xxxxxxxxx>
>> ---
>>  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
>
>
Neil, There maybe had anthor issue.
set_task_comm() is not export.So when compile md is module, it will be error.
So I think  it will be rewrite.It should rename in function call md_register_thread().
How about this way?
														Thanks!

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