iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

staging: comedi: check command started by file being polled

Browse Source 
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>
This commit is contained in:
Ian Abbott 2015-10-09 12:26:51 +01:00 committed by Greg Kroah-Hartman
parent ecf04ed34d
commit 3834234f99
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/staging/comedi/comedi_fops.c
View File

@ -2275,7 +2275,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait)
s_read = s;
if (s && s->async) {
poll_wait(file, &s->async->wait_head, wait);
if (!s->busy || !comedi_is_subdevice_running(s) ||
if (s->busy != file || !comedi_is_subdevice_running(s) ||
(s->async->cmd.flags & CMDF_WRITE) ||
comedi_buf_read_n_available(s) > 0)
mask |= POLLIN | POLLRDNORM;
@ -2287,7 +2287,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait)
if (s != s_read)
poll_wait(file, &s->async->wait_head, wait);
if (!s->busy || !comedi_is_subdevice_running(s) ||
if (s->busy != file || !comedi_is_subdevice_running(s) ||
!(s->async->cmd.flags & CMDF_WRITE) ||
comedi_buf_write_n_available(s) >= bps)
mask |= POLLOUT | POLLWRNORM;