[SCSI] pm8001: simplify workqueue usage

pm8001 manages its own list of pending works and cancel them on device
free.  It is unnecessarily complex and has a race condition - the
works are canceled but not synced, so the work could still be running
during and after the data structures are freed.

This patch simplifies workqueue usage.

* A driver specific workqueue pm8001_wq is created to serve these
  work items.

* To avoid confusion, the "queue" suffixes are dropped from work items
  and functions.

* Delayed queueing was never used.  pm8001_work now uses work_struct
  instead.

* The driver no longer keeps track of pending works.  All pm8001_works
  are queued to pm8001_wq and the workqueue is flushed as necessary.

flush_scheduled_work() usage is removed during conversion.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jack Wang <jack_wang@usish.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 18 insertions, 9 deletions

diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c
index b95285f3..002360d 100644
--- a/drivers/scsi/pm8001/pm8001_init.c
+++ b/drivers/scsi/pm8001/pm8001_init.c
@@ -51,6 +51,8 @@ static int pm8001_id;
 
 LIST_HEAD(hba_list);
 
+struct workqueue_struct *pm8001_wq;
+
 /**
  * The main structure which LLDD must register for scsi core.
  */
@@ -134,7 +136,6 @@ static void __devinit pm8001_phy_init(struct pm8001_hba_info *pm8001_ha,
 static void pm8001_free(struct pm8001_hba_info *pm8001_ha)
 {
 	int i;
-	struct pm8001_wq *wq;
 
 	if (!pm8001_ha)
 		return;
@@ -150,8 +151,7 @@ static void pm8001_free(struct pm8001_hba_info *pm8001_ha)
 	PM8001_CHIP_DISP->chip_iounmap(pm8001_ha);
 	if (pm8001_ha->shost)
 		scsi_host_put(pm8001_ha->shost);
-	list_for_each_entry(wq, &pm8001_ha->wq_list, entry)
-		cancel_delayed_work(&wq->work_q);
+	flush_workqueue(pm8001_wq);
 	kfree(pm8001_ha->tags);
 	kfree(pm8001_ha);
 }
@@ -381,7 +381,6 @@ pm8001_pci_alloc(struct pci_dev *pdev, u32 chip_id, struct Scsi_Host *shost)
 	pm8001_ha->sas = sha;
 	pm8001_ha->shost = shost;
 	pm8001_ha->id = pm8001_id++;
-	INIT_LIST_HEAD(&pm8001_ha->wq_list);
 	pm8001_ha->logging_level = 0x01;
 	sprintf(pm8001_ha->name, "%s%d", DRV_NAME, pm8001_ha->id);
 #ifdef PM8001_USE_TASKLET
@@ -758,7 +757,7 @@ static int pm8001_pci_suspend(struct pci_dev *pdev, pm_message_t state)
 	int i , pos;
 	u32 device_state;
 	pm8001_ha = sha->lldd_ha;
-	flush_scheduled_work();
+	flush_workqueue(pm8001_wq);
 	scsi_block_requests(pm8001_ha->shost);
 	pos = pci_find_capability(pdev, PCI_CAP_ID_PM);
 	if (pos == 0) {
@@ -870,17 +869,26 @@ static struct pci_driver pm8001_pci_driver = {
  */
 static int __init pm8001_init(void)
 {
-	int rc;
+	int rc = -ENOMEM;
+
+	pm8001_wq = alloc_workqueue("pm8001", 0, 0);
+	if (!pm8001_wq)
+		goto err;
+
 	pm8001_id = 0;
 	pm8001_stt = sas_domain_attach_transport(&pm8001_transport_ops);
 	if (!pm8001_stt)
-		return -ENOMEM;
+		goto err_wq;
 	rc = pci_register_driver(&pm8001_pci_driver);
 	if (rc)
-		goto err_out;
+		goto err_tp;
 	return 0;
-err_out:
+
+err_tp:
 	sas_release_transport(pm8001_stt);
+err_wq:
+	destroy_workqueue(pm8001_wq);
+err:
 	return rc;
 }
 
@@ -888,6 +896,7 @@ static void __exit pm8001_exit(void)
 {
 	pci_unregister_driver(&pm8001_pci_driver);
 	sas_release_transport(pm8001_stt);
+	destroy_workqueue(pm8001_wq);
 }
 
 module_init(pm8001_init);