diff options
| author |   Ian Abbott <abbotti@mev.co.uk> | 2010-05-19 17:22:41 +0100 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@suse.de> | 2010-06-04 13:38:53 -0700 |
| commit | d261154057c27f6c1d256b6198b0ad08733f1758 (patch) | |
| tree | 34c298f6a4390675b1e87a17893793d7e2925f1d /drivers | |
| parent | Staging: comedi: amplc_dio200: Protect counter subdevice with spinlock (diff) | |
| download | linux-dev-d261154057c27f6c1d256b6198b0ad08733f1758.tar.xz linux-dev-d261154057c27f6c1d256b6198b0ad08733f1758.zip | |
Staging: comedi: don't write to buffer if command finished
For write(), any data copied to the data buffer after the previously
set up streaming acquisition command has finished won't be used, but a
non-empty write() does not currently return 0 (or -EPIPE on error) after
the command has finished until the data buffer has been filled up.
Change this behavior to return 0 (or -EPIPE) any time after the command
has finished, without bothering to fill up the buffer with more useless
data.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index aced00e5cd10..39ed22b80229 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1576,6 +1576,19 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, while (nbytes > 0 && !retval) { set_current_state(TASK_INTERRUPTIBLE); + if (!(comedi_get_subdevice_runflags(s) & SRF_RUNNING)) { + if (count == 0) { + if (comedi_get_subdevice_runflags(s) & + SRF_ERROR) { + retval = -EPIPE; + } else { + retval = 0; + } + do_become_nonbusy(dev, s); + } + break; + } + n = nbytes; m = n; @@ -1588,16 +1601,6 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, n = m; if (n == 0) { - if (!(comedi_get_subdevice_runflags(s) & SRF_RUNNING)) { - if (comedi_get_subdevice_runflags(s) & - SRF_ERROR) { - retval = -EPIPE; - } else { - retval = 0; - } - do_become_nonbusy(dev, s); - break; - } if (file->f_flags & O_NONBLOCK) { retval = -EAGAIN; break; |