Commit 616a3548 authored Nov 08, 2013 by Ian Abbott Committed by Greg Kroah-Hartman Nov 11, 2013

staging: comedi: use refcount while reading /proc/comedi



In the seq_file 'show' handler for "/proc/comedi" - `comedi_read()` in
"comedi/proc.c",  call `comedi_dev_get_from_minor()` instead of
`comedi_dev_from_minor()` to increment the reference counter for the
`struct comedi_device` while it is being examined.  Call
`comedi_dev_put()` to decrement the reference afterwards.  Also acquire
the `attach_lock` rwsem while checking whether the device is attached.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent a200fadc

drivers/staging/comedi/proc.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -41,16 +41,20 @@ static int comedi_read(struct seq_file m, void v)
		"driver_name, board_name, n_subdevices");

		for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
		struct comedi_device *dev = comedi_dev_from_minor(i);
		struct comedi_device *dev = comedi_dev_get_from_minor(i);

		if (!dev)
		continue;

		down_read(&dev->attach_lock);
		if (dev->attached) {
		devices_q = 1;
		seq_printf(m, "%2d: %-20s %-20s %4d\n",
		i, dev->driver->driver_name,
		dev->board_name, dev->n_subdevices);
		}
		up_read(&dev->attach_lock);
		comedi_dev_put(dev);
		}
		if (!devices_q)
		seq_puts(m, "no devices\n");