linux-kernel - RE: [RFC] staging: unisys: visornic: Remove create_singlethread

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Date:	Sun, 28 Feb 2016 22:00:27 +0000
From:	"Kershner, David A" <David.Kershner@...sys.com>
To:	Amitoj Kaur Chawla <amitoj1606@...il.com>,
	"Jes.Sorensen@...hat.com" <Jes.Sorensen@...hat.com>,
	"Arfvidson, Erik" <Erik.Arfvidson@...sys.com>,
	"jkc@...hat.com" <jkc@...hat.com>,
	"Sell, Timothy C" <Timothy.Sell@...sys.com>,
	"Thompson, Bryan E." <bryan.thompson@...sys.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	*S-Par-Maintainer <SParMaintainer@...sys.com>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	"tj@...nel.org" <tj@...nel.org>,
	"outreachy-kernel@...glegroups.com" 
	<outreachy-kernel@...glegroups.com>
Subject: RE: [RFC] staging: unisys: visornic: Remove
 create_singlethread_workqueue()

> -----Original Message-----
> From: Amitoj Kaur Chawla [mailto:amitoj1606@...il.com]
> Sent: Sunday, February 28, 2016 7:57 AM
> To: Romer, Benjamin M <Benjamin.Romer@...sys.com>;
> Jes.Sorensen@...hat.com; Arfvidson, Erik <Erik.Arfvidson@...sys.com>;
> Kershner, David A <David.Kershner@...sys.com>; jkc@...hat.com; Sell,
> Timothy C <Timothy.Sell@...sys.com>; Thompson, Bryan E.
> <bryan.thompson@...sys.com>; dzickus@...hat.com;
> gregkh@...uxfoundation.org; *S-Par-Maintainer
> <SParMaintainer@...sys.com>; devel@...verdev.osuosl.org; linux-
> kernel@...r.kernel.org
> Cc: tj@...nel.org; outreachy-kernel@...glegroups.com
> Subject: [RFC] staging: unisys: visornic: Remove
> create_singlethread_workqueue()
> 
> With concurrency managed workqueues, use of dedicated workqueues
> can be replaced by using system_wq.
> Drop visornic_timeout_reset_workqueue by using system_wq.
> 
> Since there is only one work item per devdata and different
> devdatas do not need to be ordered, increase of concurrency
> level by switching to system_wq should not break anything.
> 
> cancel_work_sync() is used to ensure that work is not pending or
> executing on any CPU.
> 
> Signed-off-by: Amitoj Kaur Chawla <amitoj1606@...il.com>
> Acked-by: Tejun Heo <tj@...nel.org>

Tested on s-Par system, no issues found. 

Tested-by: David Kershner <david.kershner@...sys.com>

> ---
> Only compile tested.
> 
>  drivers/staging/unisys/visornic/visornic_main.c | 21 ++-------------------
>  1 file changed, 2 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/staging/unisys/visornic/visornic_main.c
> b/drivers/staging/unisys/visornic/visornic_main.c
> index df4f688..6749c4e 100644
> --- a/drivers/staging/unisys/visornic/visornic_main.c
> +++ b/drivers/staging/unisys/visornic/visornic_main.c
> @@ -59,8 +59,6 @@ static const struct file_operations
> debugfs_enable_ints_fops = {
>  	.write = enable_ints_write,
>  };
> 
> -static struct workqueue_struct *visornic_timeout_reset_workqueue;
> -
>  /* GUIDS for director channel type supported by this driver.  */
>  static struct visor_channeltype_descriptor visornic_channel_types[] = {
>  	/* Note that the only channel type we expect to be reported by the
> @@ -1070,7 +1068,7 @@ visornic_xmit_timeout(struct net_device *netdev)
>  		spin_unlock_irqrestore(&devdata->priv_lock, flags);
>  		return;
>  	}
> -	queue_work(visornic_timeout_reset_workqueue, &devdata-
> >timeout_reset);
> +	schedule_work(&devdata->timeout_reset);
>  	spin_unlock_irqrestore(&devdata->priv_lock, flags);
>  }
> 
> @@ -1998,7 +1996,7 @@ static void visornic_remove(struct visor_device
> *dev)
>  	}
> 
>  	/* going_away prevents new items being added to the workqueues
> */
> -	flush_workqueue(visornic_timeout_reset_workqueue);
> +	cancel_work_sync(&devdata->timeout_reset);
> 
>  	debugfs_remove_recursive(devdata->eth_debugfs_dir);
> 
> @@ -2117,21 +2115,10 @@ static int visornic_init(void)
>  	if (!ret)
>  		goto cleanup_debugfs;
> 
> -	/* create workqueue for tx timeout reset */
> -	visornic_timeout_reset_workqueue =
> -		create_singlethread_workqueue("visornic_timeout_reset");
> -	if (!visornic_timeout_reset_workqueue)
> -		goto cleanup_workqueue;
> -
>  	err = visorbus_register_visor_driver(&visornic_driver);
>  	if (!err)
>  		return 0;
> 
> -cleanup_workqueue:
> -	if (visornic_timeout_reset_workqueue) {
> -		flush_workqueue(visornic_timeout_reset_workqueue);
> -		destroy_workqueue(visornic_timeout_reset_workqueue);
> -	}
>  cleanup_debugfs:
>  	debugfs_remove_recursive(visornic_debugfs_dir);
> 
> @@ -2147,10 +2134,6 @@ static void visornic_cleanup(void)
>  {
>  	visorbus_unregister_visor_driver(&visornic_driver);
> 
> -	if (visornic_timeout_reset_workqueue) {
> -		flush_workqueue(visornic_timeout_reset_workqueue);
> -		destroy_workqueue(visornic_timeout_reset_workqueue);
> -	}
>  	debugfs_remove_recursive(visornic_debugfs_dir);
>  }
> 
> --
> 1.9.1