[RFC] staging: unisys: visorbus: visorchipset: Remove create_singlethread_workqueue()

[Kershner, David A]

> -----Original Message-----
> From: Amitoj Kaur Chawla [mailto:amitoj1606 at gmail.com]
> Sent: Sunday, February 28, 2016 7:44 AM
> To: Romer, Benjamin M <Benjamin.Romer at unisys.com>;
> Jes.Sorensen at redhat.com; Arfvidson, Erik <Erik.Arfvidson at unisys.com>;
> Kershner, David A <David.Kershner at unisys.com>; jkc at redhat.com; Sell,
> Timothy C <Timothy.Sell at unisys.com>; Thompson, Bryan E.
> <bryan.thompson at unisys.com>; dzickus at redhat.com;
> kenneth.depro at unisys.com; gregkh at linuxfoundation.org; *S-Par-
> Maintainer <SParMaintainer at unisys.com>; devel at driverdev.osuosl.org;
> linux-kernel at vger.kernel.org
> Cc: tj at kernel.org; outreachy-kernel at googlegroups.com
> Subject: [RFC] staging: unisys: visorbus: visorchipset: Remove
> create_singlethread_workqueue()
> 
> With concurrency managed workqueues, use of dedicated workqueues
> can be replaced by using system_wq. Drop periodic_controlvm_workqueue
> by using system_wq.
> 
> Since there is only one work item periodic_controlvm_work and
> different periodic_controlvm_works do not need to be ordered, increase
> of concurrency level by switching to system_wq should not break anything.
> 
> cancel_delayed_work_sync() is used to ensure that work is not pending
> or executing on any CPU.
> 
> Signed-off-by: Amitoj Kaur Chawla <amitoj1606 at gmail.com>
> Acked-by: Tejun Heo <tj at kernel.org>

Tested on s-Par system, no issues found. 

Tested-by: David Kershner <david.kershner at unisys.com>

> ---
> Only compile tested.
> 
>  drivers/staging/unisys/visorbus/visorchipset.c | 23 ++++-------------------
>  1 file changed, 4 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/staging/unisys/visorbus/visorchipset.c
> b/drivers/staging/unisys/visorbus/visorchipset.c
> index b75b063..c4c71c6 100644
> --- a/drivers/staging/unisys/visorbus/visorchipset.c
> +++ b/drivers/staging/unisys/visorbus/visorchipset.c
> @@ -102,7 +102,6 @@ struct parser_context {
>  };
> 
>  static struct delayed_work periodic_controlvm_work;
> -static struct workqueue_struct *periodic_controlvm_workqueue;
>  static DEFINE_SEMAPHORE(notifier_lock);
> 
>  static struct cdev file_cdev;
> @@ -1913,8 +1912,7 @@ cleanup:
>  			poll_jiffies =
> POLLJIFFIES_CONTROLVMCHANNEL_FAST;
>  	}
> 
> -	queue_delayed_work(periodic_controlvm_workqueue,
> -			   &periodic_controlvm_work, poll_jiffies);
> +	schedule_delayed_work(&periodic_controlvm_work, poll_jiffies);
>  }
> 
>  static void
> @@ -2011,8 +2009,7 @@ cleanup:
> 
>  	poll_jiffies = POLLJIFFIES_CONTROLVMCHANNEL_SLOW;
> 
> -	queue_delayed_work(periodic_controlvm_workqueue,
> -			   &periodic_controlvm_work, poll_jiffies);
> +	schedule_delayed_work(&periodic_controlvm_work, poll_jiffies);
>  }
> 
>  static void
> @@ -2299,19 +2296,10 @@ visorchipset_init(struct acpi_device
> *acpi_device)
>  	else
>  		INIT_DELAYED_WORK(&periodic_controlvm_work,
>  				  controlvm_periodic_work);
> -	periodic_controlvm_workqueue =
> -	    create_singlethread_workqueue("visorchipset_controlvm");
> 
> -	if (!periodic_controlvm_workqueue) {
> -		POSTCODE_LINUX_2(CREATE_WORKQUEUE_FAILED_PC,
> -				 DIAG_SEVERITY_ERR);
> -		rc = -ENOMEM;
> -		goto cleanup;
> -	}
>  	most_recent_message_jiffies = jiffies;
>  	poll_jiffies = POLLJIFFIES_CONTROLVMCHANNEL_FAST;
> -	queue_delayed_work(periodic_controlvm_workqueue,
> -			   &periodic_controlvm_work, poll_jiffies);
> +	schedule_delayed_work(&periodic_controlvm_work, poll_jiffies);
> 
>  	visorchipset_platform_device.dev.devt = major_dev;
>  	if (platform_device_register(&visorchipset_platform_device) < 0) {
> @@ -2346,10 +2334,7 @@ visorchipset_exit(struct acpi_device *acpi_device)
> 
>  	visorbus_exit();
> 
> -	cancel_delayed_work(&periodic_controlvm_work);
> -	flush_workqueue(periodic_controlvm_workqueue);
> -	destroy_workqueue(periodic_controlvm_workqueue);
> -	periodic_controlvm_workqueue = NULL;
> +	cancel_delayed_work_sync(&periodic_controlvm_work);
>  	destroy_controlvm_payload_info(&controlvm_payload_info);
> 
>  	memset(&g_chipset_msg_hdr, 0, sizeof(struct
> controlvm_message_header));
> --
> 1.9.1