From 065785618c6712a39262e4183efce616f895e5ad Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Fri, 19 Feb 2016 16:13:52 +0000 Subject: [PATCH] staging: comedi: COMEDI_BUFINFO: update buffer before becoming non-busy The `COMEDI_BUFINFO` ioctl is used to advance the current position in the buffer by a specified amount (which can be 0) and get the new position. For an asynchronous command in the "read" direction, if the command has finished acquiring data normally, `do_become_nonbusy()` is called to terminate the command. That resets the buffer position, and currently, the position information returned back to the user is after the buffer has been reset. It should be more useful to return the buffer position before the reset, so move the call to `do_become_nonbusy()` after the code that gets the updated buffer position. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/comedi_fops.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 04d6040246ee..e625ef2bcb7f 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1111,6 +1111,7 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, struct comedi_bufinfo bi; struct comedi_subdevice *s; struct comedi_async *async; + bool become_nonbusy = false; if (copy_from_user(&bi, arg, sizeof(bi))) return -EFAULT; @@ -1149,7 +1150,7 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, if (comedi_is_subdevice_idle(s) && comedi_buf_read_n_available(s) == 0) - do_become_nonbusy(dev, s); + become_nonbusy = true; } bi.bytes_written = 0; } else { @@ -1168,6 +1169,9 @@ copyback_position: bi.buf_read_count = async->buf_read_count; bi.buf_read_ptr = async->buf_read_ptr; + if (become_nonbusy) + do_become_nonbusy(dev, s); + copyback: if (copy_to_user(arg, &bi, sizeof(bi))) return -EFAULT; -- 2.39.5