From 3834234f99a07d1a84918cb15e9431420c5405f4 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Fri, 9 Oct 2015 12:26:51 +0100 Subject: [PATCH] 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 Reviewed-by: H Hartley Sweeten Signed-off-by: Greg Kroah-Hartman --- 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 42f6971c8061..1d6bef285821 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -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; -- 2.20.1