staging: comedi: allow buffer resize if previous resize failed

When a comedi device is successfully attached, those subdevices that
support asynchronous commands will have had buffers allocated
successfully.  It is possible to resize the buffers afterwards, but if
the resize fails the subdevice is left with no buffer
(`s->async->prealloc_buf == NULL`).  Currently, this also causes any
subsequent attempts to resize the buffer to fail with an error, which
seems like a bad idea.

Remove the check in `resize_async_buffer()` that causes the resize to
fail if the subdevice currently has no buffer (presumably due to the
failure of a previous resize attempt).  Callers of
`resize_async_buffer()` have already checked that the subdevice is
allowed to have a buffer.

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

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 00f2547024ec6b1a2d2abf6abf52dbcc1697dbc8..924c54c9c31fad595d1cdf9331db17d8c40413f4 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -246,9 +246,6 @@ static int resize_async_buffer(struct comedi_device *dev,
                return -EBUSY;
        }
 
-       if (!async->prealloc_buf)
-               return -EINVAL;
-
        /* make sure buffer is an integral number of pages
         * (we round up) */
        new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;