staging: comedi: check command started by file being polled
authorIan Abbott <abbotti@mev.co.uk>
Fri, 9 Oct 2015 11:26:51 +0000 (12:26 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 13 Oct 2015 17:28:40 +0000 (10:28 -0700)
commit3834234f99a07d1a84918cb15e9431420c5405f4
tree001c13c3f3295c70c9ac7be2f61b276ad6852941
parentecf04ed34d65b735bbdfa9ae8ea378ffc0faa9f6
staging: comedi: check command started by file being polled

Currently, the "poll" file operation checks if an asynchronous "read"
(or "write" command is active on the "read" (or "write" subdevice, but
does not consider whether the command was started from the file object
being polled.  Since that is the only file object able to read (or
write) data, take it into consideration.

With this change, if no read (or write) command is running on the
subdevice, or it is started by a different file object, the file object
is marked as readable (or writeable) regardless, but the read (or write)
file operation will return an error.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/staging/comedi/comedi_fops.c