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cciss: Use one scan thread per controller and fix hang during rmmod

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Replace the use of one scan kthread per controller with one per driver.
Use a queue to hold a list of controllers that need to be rescanned with
routines to add and remove controllers from the queue.

Fix locking and completion handling to prevent a hang during rmmod.

Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Acked-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Andrew Patterson 2009-09-17 13:46:58 -05:00 committed by Jens Axboe
parent c64bebcd7f
commit b368c9dd65
2 changed files with 141 additions and 22 deletions
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156
drivers/block/cciss.c
View File

@ -40,6 +40,7 @@
#include <linux/hdreg.h>
#include <linux/spinlock.h>
#include <linux/compat.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <asm/io.h>
@ -156,6 +157,10 @@ static struct board_type products[] = {
static ctlr_info_t *hba[MAX_CTLR];
static struct task_struct *cciss_scan_thread;
static DEFINE_MUTEX(scan_mutex);
static LIST_HEAD(scan_q);
static void do_cciss_request(struct request_queue *q);
static irqreturn_t do_cciss_intr(int irq, void *dev_id);
static int cciss_open(struct block_device *bdev, fmode_t mode);
@ -3233,20 +3238,121 @@ static irqreturn_t do_cciss_intr(int irq, void *dev_id)
return IRQ_HANDLED;
}
/**
* add_to_scan_list() - add controller to rescan queue
* @h: Pointer to the controller.
*
* Adds the controller to the rescan queue if not already on the queue.
*
* returns 1 if added to the queue, 0 if skipped (could be on the
* queue already, or the controller could be initializing or shutting
* down).
**/
static int add_to_scan_list(struct ctlr_info *h)
{
struct ctlr_info *test_h;
int found = 0;
int ret = 0;
if (h->busy_initializing)
return 0;
if (!mutex_trylock(&h->busy_shutting_down))
return 0;
mutex_lock(&scan_mutex);
list_for_each_entry(test_h, &scan_q, scan_list) {
if (test_h == h) {
found = 1;
break;
}
}
if (!found && !h->busy_scanning) {
INIT_COMPLETION(h->scan_wait);
list_add_tail(&h->scan_list, &scan_q);
ret = 1;
}
mutex_unlock(&scan_mutex);
mutex_unlock(&h->busy_shutting_down);
return ret;
}
/**
* remove_from_scan_list() - remove controller from rescan queue
* @h: Pointer to the controller.
*
* Removes the controller from the rescan queue if present. Blocks if
* the controller is currently conducting a rescan.
**/
static void remove_from_scan_list(struct ctlr_info *h)
{
struct ctlr_info *test_h, *tmp_h;
int scanning = 0;
mutex_lock(&scan_mutex);
list_for_each_entry_safe(test_h, tmp_h, &scan_q, scan_list) {
if (test_h == h) {
list_del(&h->scan_list);
complete_all(&h->scan_wait);
mutex_unlock(&scan_mutex);
return;
}
}
if (&h->busy_scanning)
scanning = 0;
mutex_unlock(&scan_mutex);
if (scanning)
wait_for_completion(&h->scan_wait);
}
/**
* scan_thread() - kernel thread used to rescan controllers
* @data: Ignored.
*
* A kernel thread used scan for drive topology changes on
* controllers. The thread processes only one controller at a time
* using a queue. Controllers are added to the queue using
* add_to_scan_list() and removed from the queue either after done
* processing or using remove_from_scan_list().
*
* returns 0.
**/
static int scan_thread(void *data)
{
ctlr_info_t *h = data;
int rc;
DECLARE_COMPLETION_ONSTACK(wait);
h->rescan_wait = &wait;
struct ctlr_info *h;
for (;;) {
rc = wait_for_completion_interruptible(&wait);
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
if (kthread_should_stop())
break;
if (!rc)
rebuild_lun_table(h, 0);
while (1) {
mutex_lock(&scan_mutex);
if (list_empty(&scan_q)) {
mutex_unlock(&scan_mutex);
break;
}
h = list_entry(scan_q.next,
struct ctlr_info,
scan_list);
list_del(&h->scan_list);
h->busy_scanning = 1;
mutex_unlock(&scan_mutex);
if (h) {
rebuild_lun_table(h, 0);
complete_all(&h->scan_wait);
mutex_lock(&scan_mutex);
h->busy_scanning = 0;
mutex_unlock(&scan_mutex);
}
}
}
return 0;
}
@ -3269,8 +3375,8 @@ static int check_for_unit_attention(ctlr_info_t *h, CommandList_struct *c)
case REPORT_LUNS_CHANGED:
printk(KERN_WARNING "cciss%d: report LUN data "
"changed\n", h->ctlr);
if (h->rescan_wait)
complete(h->rescan_wait);
add_to_scan_list(h);
wake_up_process(cciss_scan_thread);
return 1;
break;
case POWER_OR_RESET:
@ -3919,6 +4025,7 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
hba[i]->busy_initializing = 1;
INIT_HLIST_HEAD(&hba[i]->cmpQ);
INIT_HLIST_HEAD(&hba[i]->reqQ);
mutex_init(&hba[i]->busy_shutting_down);
if (cciss_pci_init(hba[i], pdev) != 0)
goto clean0;
@ -3927,6 +4034,8 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
hba[i]->ctlr = i;
hba[i]->pdev = pdev;
init_completion(&hba[i]->scan_wait);
if (cciss_create_hba_sysfs_entry(hba[i]))
goto clean0;
@ -4036,14 +4145,8 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
hba[i]->cciss_max_sectors = 2048;
hba[i]->busy_initializing = 0;
rebuild_lun_table(hba[i], 1);
hba[i]->cciss_scan_thread = kthread_run(scan_thread, hba[i],
"cciss_scan%02d", i);
if (IS_ERR(hba[i]->cciss_scan_thread))
return PTR_ERR(hba[i]->cciss_scan_thread);
hba[i]->busy_initializing = 0;
return 1;
clean4:
@ -4126,8 +4229,9 @@ static void __devexit cciss_remove_one(struct pci_dev *pdev)
return;
}
kthread_stop(hba[i]->cciss_scan_thread);
mutex_lock(&hba[i]->busy_shutting_down);
remove_from_scan_list(hba[i]);
remove_proc_entry(hba[i]->devname, proc_cciss);
unregister_blkdev(hba[i]->major, hba[i]->devname);
@ -4174,6 +4278,7 @@ static void __devexit cciss_remove_one(struct pci_dev *pdev)
pci_release_regions(pdev);
pci_set_drvdata(pdev, NULL);
cciss_destroy_hba_sysfs_entry(hba[i]);
mutex_unlock(&hba[i]->busy_shutting_down);
free_hba(i);
}
@ -4206,15 +4311,25 @@ static int __init cciss_init(void)
if (err)
return err;
/* Start the scan thread */
cciss_scan_thread = kthread_run(scan_thread, NULL, "cciss_scan");
if (IS_ERR(cciss_scan_thread)) {
err = PTR_ERR(cciss_scan_thread);
goto err_bus_unregister;
}
/* Register for our PCI devices */
err = pci_register_driver(&cciss_pci_driver);
if (err)
goto err_bus_register;
goto err_thread_stop;
return 0;
err_bus_register:
err_thread_stop:
kthread_stop(cciss_scan_thread);
err_bus_unregister:
bus_unregister(&cciss_bus_type);
return err;
}
@ -4231,6 +4346,7 @@ static void __exit cciss_cleanup(void)
cciss_remove_one(hba[i]->pdev);
}
}
kthread_stop(cciss_scan_thread);
remove_proc_entry("driver/cciss", NULL);
bus_unregister(&cciss_bus_type);
}

7
drivers/block/cciss.h
View File

@ -2,6 +2,7 @@
#define CCISS_H
#include <linux/genhd.h>
#include <linux/mutex.h>
#include "cciss_cmd.h"
@ -108,6 +109,8 @@ struct ctlr_info
int nr_frees;
int busy_configuring;
int busy_initializing;
int busy_scanning;
struct mutex busy_shutting_down;
/* This element holds the zero based queue number of the last
* queue to be started. It is used for fairness.
@ -122,8 +125,8 @@ struct ctlr_info
/* and saved for later processing */
#endif
unsigned char alive;
struct completion *rescan_wait;
struct task_struct *cciss_scan_thread;
struct list_head scan_list;
struct completion scan_wait;
struct device dev;
};