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authorIan Abbott <abbotti@mev.co.uk>2010-05-19 17:22:41 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2010-06-04 13:38:53 -0700
commitd261154057c27f6c1d256b6198b0ad08733f1758 (patch)
tree34c298f6a4390675b1e87a17893793d7e2925f1d
parentee4063fa6bd801fa6ea045f23a2934db009b3dac (diff)
downloadlinux-d261154057c27f6c1d256b6198b0ad08733f1758.tar.bz2
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>
-rw-r--r--drivers/staging/comedi/comedi_fops.c23
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;