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staging:rts_pstor: fix thread synchronization flow
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Using different completion variables to synchronize different kernel threads

This patch fix a bug that may cause memory leak when driver
disconnected. This is not a very urgent bug. Because with the default
setting, driver disconnectting routine won't be called except when Linux
is shut down. But if the option auto_delink_en is set, a small number of
memory would leak out after memory card unplugged.

Signed-off-by: wwang <wei_wang@realsil.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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wwang authored and Greg Kroah-Hartman committed Aug 8, 2011
1 parent f8d73aa commit f704648
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Showing 2 changed files with 50 additions and 68 deletions.
109 changes: 42 additions & 67 deletions drivers/staging/rts_pstor/rtsx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,12 +66,6 @@ static int msi_en;
module_param(msi_en, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(msi_en, "enable msi");

/* These are used to make sure the module doesn't unload before all the
* threads have exited.
*/
static atomic_t total_threads = ATOMIC_INIT(0);
static DECLARE_COMPLETION(threads_gone);

static irqreturn_t rtsx_interrupt(int irq, void *dev_id);

/***********************************************************************
Expand Down Expand Up @@ -192,7 +186,7 @@ static int queuecommand_lck(struct scsi_cmnd *srb,
/* enqueue the command and wake up the control thread */
srb->scsi_done = done;
chip->srb = srb;
up(&(dev->sema));
complete(&dev->cmnd_ready);

return 0;
}
Expand Down Expand Up @@ -475,7 +469,7 @@ static int rtsx_control_thread(void *__dev)
current->flags |= PF_NOFREEZE;

for (;;) {
if (down_interruptible(&dev->sema))
if (wait_for_completion_interruptible(&dev->cmnd_ready))
break;

/* lock the device pointers */
Expand Down Expand Up @@ -557,8 +551,6 @@ static int rtsx_control_thread(void *__dev)
mutex_unlock(&dev->dev_mutex);
} /* for (;;) */

scsi_host_put(host);

/* notify the exit routine that we're actually exiting now
*
* complete()/wait_for_completion() is similar to up()/down(),
Expand All @@ -573,15 +565,14 @@ static int rtsx_control_thread(void *__dev)
* This is important in preemption kernels, which transfer the flow
* of execution immediately upon a complete().
*/
complete_and_exit(&threads_gone, 0);
complete_and_exit(&dev->control_exit, 0);
}


static int rtsx_polling_thread(void *__dev)
{
struct rtsx_dev *dev = (struct rtsx_dev *)__dev;
struct rtsx_chip *chip = dev->chip;
struct Scsi_Host *host = rtsx_to_host(dev);
struct sd_info *sd_card = &(chip->sd_card);
struct xd_info *xd_card = &(chip->xd_card);
struct ms_info *ms_card = &(chip->ms_card);
Expand Down Expand Up @@ -621,8 +612,7 @@ static int rtsx_polling_thread(void *__dev)
mutex_unlock(&dev->dev_mutex);
}

scsi_host_put(host);
complete_and_exit(&threads_gone, 0);
complete_and_exit(&dev->polling_exit, 0);
}

/*
Expand Down Expand Up @@ -699,29 +689,38 @@ static void rtsx_release_resources(struct rtsx_dev *dev)
{
printk(KERN_INFO "-- %s\n", __func__);

/* Tell the control thread to exit. The SCSI host must
* already have been removed so it won't try to queue
* any more commands.
*/
printk(KERN_INFO "-- sending exit command to thread\n");
complete(&dev->cmnd_ready);
if (dev->ctl_thread)
wait_for_completion(&dev->control_exit);
if (dev->polling_thread)
wait_for_completion(&dev->polling_exit);

wait_timeout(200);

if (dev->rtsx_resv_buf) {
dma_free_coherent(&(dev->pci->dev), HOST_CMDS_BUF_LEN,
dma_free_coherent(&(dev->pci->dev), RTSX_RESV_BUF_LEN,
dev->rtsx_resv_buf, dev->rtsx_resv_buf_addr);
dev->chip->host_cmds_ptr = NULL;
dev->chip->host_sg_tbl_ptr = NULL;
}

pci_disable_device(dev->pci);
pci_release_regions(dev->pci);

if (dev->irq > 0) {
if (dev->irq > 0)
free_irq(dev->irq, (void *)dev);
}
if (dev->chip->msi_en) {
if (dev->chip->msi_en)
pci_disable_msi(dev->pci);
}
if (dev->remap_addr)
iounmap(dev->remap_addr);

/* Tell the control thread to exit. The SCSI host must
* already have been removed so it won't try to queue
* any more commands.
*/
printk(KERN_INFO "-- sending exit command to thread\n");
up(&dev->sema);
pci_disable_device(dev->pci);
pci_release_regions(dev->pci);

rtsx_release_chip(dev->chip);
kfree(dev->chip);
}

/* First stage of disconnect processing: stop all commands and remove
Expand All @@ -739,6 +738,7 @@ static void quiesce_and_remove_host(struct rtsx_dev *dev)
scsi_unlock(host);
mutex_unlock(&dev->dev_mutex);
wake_up(&dev->delay_wait);
wait_for_completion(&dev->scanning_done);

/* Wait some time to let other threads exist */
wait_timeout(100);
Expand Down Expand Up @@ -793,8 +793,7 @@ static int rtsx_scan_thread(void *__dev)
/* Should we unbind if no devices were detected? */
}

scsi_host_put(rtsx_to_host(dev));
complete_and_exit(&threads_gone, 0);
complete_and_exit(&dev->scanning_done, 0);
}

static void rtsx_init_options(struct rtsx_chip *chip)
Expand Down Expand Up @@ -941,8 +940,11 @@ static int __devinit rtsx_probe(struct pci_dev *pci, const struct pci_device_id

spin_lock_init(&dev->reg_lock);
mutex_init(&(dev->dev_mutex));
sema_init(&(dev->sema), 0);
init_completion(&dev->cmnd_ready);
init_completion(&dev->control_exit);
init_completion(&dev->polling_exit);
init_completion(&(dev->notify));
init_completion(&dev->scanning_done);
init_waitqueue_head(&dev->delay_wait);

dev->pci = pci;
Expand Down Expand Up @@ -992,28 +994,22 @@ static int __devinit rtsx_probe(struct pci_dev *pci, const struct pci_device_id
pci_set_master(pci);
synchronize_irq(dev->irq);

err = scsi_add_host(host, &pci->dev);
if (err) {
printk(KERN_ERR "Unable to add the scsi host\n");
goto errout;
}

rtsx_init_chip(dev->chip);

/* Start up our control thread */
th = kthread_create(rtsx_control_thread, dev, CR_DRIVER_NAME);
th = kthread_run(rtsx_control_thread, dev, CR_DRIVER_NAME);
if (IS_ERR(th)) {
printk(KERN_ERR "Unable to start control thread\n");
err = PTR_ERR(th);
goto errout;
}
dev->ctl_thread = th;

/* Take a reference to the host for the control thread and
* count it among all the threads we have launched. Then
* start it up. */
scsi_host_get(rtsx_to_host(dev));
atomic_inc(&total_threads);
wake_up_process(th);
err = scsi_add_host(host, &pci->dev);
if (err) {
printk(KERN_ERR "Unable to add the scsi host\n");
goto errout;
}

/* Start up the thread for delayed SCSI-device scanning */
th = kthread_create(rtsx_scan_thread, dev, "rtsx-scan");
Expand All @@ -1024,28 +1020,17 @@ static int __devinit rtsx_probe(struct pci_dev *pci, const struct pci_device_id
goto errout;
}

/* Take a reference to the host for the scanning thread and
* count it among all the threads we have launched. Then
* start it up. */
scsi_host_get(rtsx_to_host(dev));
atomic_inc(&total_threads);
wake_up_process(th);

/* Start up the thread for polling thread */
th = kthread_create(rtsx_polling_thread, dev, "rtsx-polling");
th = kthread_run(rtsx_polling_thread, dev, "rtsx-polling");
if (IS_ERR(th)) {
printk(KERN_ERR "Unable to start the device-polling thread\n");
quiesce_and_remove_host(dev);
err = PTR_ERR(th);
goto errout;
}

/* Take a reference to the host for the polling thread and
* count it among all the threads we have launched. Then
* start it up. */
scsi_host_get(rtsx_to_host(dev));
atomic_inc(&total_threads);
wake_up_process(th);
dev->polling_thread = th;

pci_set_drvdata(pci, dev);

Expand Down Expand Up @@ -1108,16 +1093,6 @@ static void __exit rtsx_exit(void)

pci_unregister_driver(&driver);

/* Don't return until all of our control and scanning threads
* have exited. Since each thread signals threads_gone as its
* last act, we have to call wait_for_completion the right number
* of times.
*/
while (atomic_read(&total_threads) > 0) {
wait_for_completion(&threads_gone);
atomic_dec(&total_threads);
}

printk(KERN_INFO "%s module exit\n", CR_DRIVER_NAME);
}

Expand Down
9 changes: 8 additions & 1 deletion drivers/staging/rts_pstor/rtsx.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -112,9 +112,16 @@ struct rtsx_dev {
/* locks */
spinlock_t reg_lock;

struct task_struct *ctl_thread; /* the control thread */
struct task_struct *polling_thread; /* the polling thread */

/* mutual exclusion and synchronization structures */
struct semaphore sema; /* to sleep thread on */
struct completion cmnd_ready; /* to sleep thread on */
struct completion control_exit; /* control thread exit */
struct completion polling_exit; /* polling thread exit */
struct completion notify; /* thread begin/end */
struct completion scanning_done; /* wait for scan thread */

wait_queue_head_t delay_wait; /* wait during scan, reset */
struct mutex dev_mutex;

Expand Down

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