The main mutex in a comedi device can get held for quite a while when processing comedi instructions, so for performance reasons, the "read" and "write" file operations do not use it; they use use the `attach_lock` rwsemaphore to protect against the comedi device becoming detached at an inopportune moment. Do the same for the "poll" file operation.
Signed-off-by: Ian Abbott <[email protected]> --- drivers/staging/comedi/comedi_fops.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 07bb197..88e9334 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2264,7 +2264,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) struct comedi_device *dev = cfp->dev; struct comedi_subdevice *s, *s_read; - mutex_lock(&dev->mutex); + down_read(&dev->attach_lock); if (!dev->attached) { dev_dbg(dev->class_dev, "no driver attached\n"); @@ -2294,7 +2294,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) } done: - mutex_unlock(&dev->mutex); + up_read(&dev->attach_lock); return mask; } -- 2.6.1 _______________________________________________ devel mailing list [email protected] http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
