linux-kernel - Re: [PATCH 17/20 v1] [SCSI] mpt3sas: Use alloc_ordered_workqueue() API instead of create_singlethread

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Date:	Thu, 18 Jun 2015 18:36:29 +0530
From:	Sreekanth Reddy <sreekanth.reddy@...gotech.com>
To:	Joe Lawrence <joe.lawrence@...atus.com>
Cc:	"jejb@...nel.org" <jejb@...nel.org>,
	Christoph Hellwig <hch@...radead.org>,
	Johannes Thumshirn <jthumshirn@...e.de>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	Sathya Prakash <Sathya.Prakash@...gotech.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 17/20 v1] [SCSI] mpt3sas: Use alloc_ordered_workqueue()
 API instead of create_singlethread_workqueue() API

On Thu, Jun 18, 2015 at 5:40 PM, Joe Lawrence <joe.lawrence@...atus.com> wrote:
> On 06/16/2015 01:37 AM, Sreekanth Reddy wrote:
>> Created a thread using alloc_ordered_workqueue() API in order to process
>> the works from firmware Work-queue sequentially instead of
>> create_singlethread_workqueue() API.
>>
>> Changes in v1:
>>     No need to check for backport compatibility in the upstream kernel.
>> so removing the else section where driver use
>> create_singlethread_workqueue() API if alloc_ordered_workqueue() API is
>> not defined, This else section is not required since in the latest upstream
>> kernel this alloc_ordered_workqueue() API is always defined.
>>
>> Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@...gotech.com>
>> ---
>>  drivers/scsi/mpt3sas/mpt3sas_scsih.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
>> index b848458..7e5926c 100644
>> --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
>> +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
>> @@ -8085,8 +8085,8 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>       /* event thread */
>>       snprintf(ioc->firmware_event_name, sizeof(ioc->firmware_event_name),
>>           "fw_event%d", ioc->id);
>> -     ioc->firmware_event_thread = create_singlethread_workqueue(
>> -         ioc->firmware_event_name);
>> +     ioc->firmware_event_thread = alloc_ordered_workqueue(
>> +         ioc->firmware_event_name, WQ_MEM_RECLAIM);
>>       if (!ioc->firmware_event_thread) {
>>               pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
>>                   ioc->name, __FILE__, __LINE__, __func__);
>>
>
> Hi Sreekanth,
>
> Is this change still needed after e09c2c2954684 workqueue: apply
> __WQ_ORDERED to create_singlethread_workqueue() ?  (3.17+)

I won't say that it is compulsory required, but I feel it is better if
these changes are included. since initially we thought that thread
created by using create_singlethread_workqueue() will process the
works sequentially but in-between  it has broken and then it is fixed
by Tejun.  So I thought it is better to directly use the
alloc_ordered_workqueue() as create_singlethead_workqueue() API also
invoked the same API.

>
> In upstream, this change looks cosmetic (unless Tejun has a preference
> for one over the other), but maybe converting to alloc_ordered_workqueue
> keeps your in house version in closer sync?
>
> Thanks,
>
> -- Joe



-- 

Regards,
Sreekanth
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