diff options
author | Federico Vaga <federico.vaga@gmail.com> | 2011-10-29 09:45:39 +0200 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-12-09 08:54:42 -0800 |
commit | 3762465d4a6c6a92a93d361b95dd453fd736ba73 (patch) | |
tree | 949323bc7c567cd834f528345e44bb1b53efa02b /drivers | |
parent | 7994d8747d9ac088be8a2136dc25ea30135ca1e8 (diff) |
Staging: comedi: fix mmap_count
commit df30b21cb0eed5ba8a8e0cdfeebc66ba8cde821d upstream.
In comedi_fops, mmap_count is decremented at comedi_vm_ops->close but
it is not incremented at comedi_vm_ops->open. This may result in a negative
counter. The patch introduces the open method to keep the counter
consistent.
The bug was triggerd by this sample code:
mmap(0, ...., comedi_fd);
fork();
exit(0);
Acked-by: Alessandro Rubini <rubini@gnudd.com>
Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index bfda750b42b4..bf55ccec65a0 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1432,7 +1432,21 @@ static int do_cancel(struct comedi_device *dev, struct comedi_subdevice *s) return ret; } -static void comedi_unmap(struct vm_area_struct *area) + +static void comedi_vm_open(struct vm_area_struct *area) +{ + struct comedi_async *async; + struct comedi_device *dev; + + async = area->vm_private_data; + dev = async->subdevice->device; + + mutex_lock(&dev->mutex); + async->mmap_count++; + mutex_unlock(&dev->mutex); +} + +static void comedi_vm_close(struct vm_area_struct *area) { struct comedi_async *async; struct comedi_device *dev; @@ -1446,7 +1460,8 @@ static void comedi_unmap(struct vm_area_struct *area) } static struct vm_operations_struct comedi_vm_ops = { - .close = comedi_unmap, + .open = comedi_vm_open, + .close = comedi_vm_close, }; static int comedi_mmap(struct file *file, struct vm_area_struct *vma) |