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staging: comedi: increment reference while file open

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In the 'open' file operation handler `comedi_open()` in "comedi_fops.c",
call `comedi_dev_get_from_minor()` instead of `comedi_dev_from_minor()`
to get the pointer to the `struct comedi_device`.  This increments the
reference to prevent it being freed.  Call `comedi_dev_put()` to
decrement the reference  on failure, and also call it from the 'release'
file operation handler `comedi_close()`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2013-11-08 15:03:34 +00:00 committed by Greg Kroah-Hartman
parent b449c1cad7
commit fc406986d4
1 changed files with 16 additions and 12 deletions
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28
drivers/staging/comedi/comedi_fops.c
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@ -2348,7 +2348,8 @@ out:
static int comedi_open(struct inode *inode, struct file *file)
{
const unsigned minor = iminor(inode);
struct comedi_device *dev = comedi_dev_from_minor(minor);
struct comedi_device *dev = comedi_dev_get_from_minor(minor);
int rc;
if (!dev) {
DPRINTK("invalid minor number\n");
@ -2373,8 +2374,8 @@ static int comedi_open(struct inode *inode, struct file *file)
goto ok;
if (!capable(CAP_NET_ADMIN) && dev->in_request_module) {
DPRINTK("in request module\n");
mutex_unlock(&dev->mutex);
return -ENODEV;
rc = -ENODEV;
goto out;
}
if (capable(CAP_NET_ADMIN) && dev->in_request_module)
goto ok;
@ -2391,8 +2392,8 @@ static int comedi_open(struct inode *inode, struct file *file)
if (!dev->attached && !capable(CAP_NET_ADMIN)) {
DPRINTK("not attached and not CAP_NET_ADMIN\n");
mutex_unlock(&dev->mutex);
return -ENODEV;
rc = -ENODEV;
goto out;
}
ok:
__module_get(THIS_MODULE);
@ -2400,26 +2401,28 @@ ok:
if (dev->attached) {
if (!try_module_get(dev->driver->module)) {
module_put(THIS_MODULE);
mutex_unlock(&dev->mutex);
return -ENOSYS;
rc = -ENOSYS;
goto out;
}
}
if (dev->attached && dev->use_count == 0 && dev->open) {
int rc = dev->open(dev);
rc = dev->open(dev);
if (rc < 0) {
module_put(dev->driver->module);
module_put(THIS_MODULE);
mutex_unlock(&dev->mutex);
return rc;
goto out;
}
}
dev->use_count++;
rc = 0;
out:
mutex_unlock(&dev->mutex);
return 0;
if (rc)
comedi_dev_put(dev);
return rc;
}
static int comedi_fasync(int fd, struct file *file, int on)
@ -2465,6 +2468,7 @@ static int comedi_close(struct inode *inode, struct file *file)
dev->use_count--;
mutex_unlock(&dev->mutex);
comedi_dev_put(dev);
return 0;
}