Fix previous commit. For COMEDI_BUFINFO, if command not active, report back

the last buffer position instead of random junk.

diff --git a/comedi/comedi_fops.c b/comedi/comedi_fops.c
index d63302d6e67256096e1398081f38061238319f5d..1218248ef2ee72b6f5f44b2e7c3c101bf622a3a1 100644 (file)
--- a/comedi/comedi_fops.c
+++ b/comedi/comedi_fops.c
@@ -578,6 +578,7 @@ static int do_bufinfo_ioctl(comedi_device * dev, void *arg, void *file)
        comedi_bufinfo bi;
        comedi_subdevice *s;
        comedi_async *async;
+       int retval = 0;
 
        if (copy_from_user(&bi, arg, sizeof(comedi_bufinfo)))
                return -EFAULT;
@@ -604,28 +605,52 @@ static int do_bufinfo_ioctl(comedi_device * dev, void *arg, void *file)
        if (!s->busy) {
                bi.bytes_read = 0;
                bi.bytes_written = 0;
-               goto copyback;
+               goto copyback_position;
        }
        if (s->busy != file)
                return -EACCES;
 
-       if (bi.bytes_read && (s->subdev_flags & SDF_CMD_READ)) {
-               bi.bytes_read = comedi_buf_read_alloc(async, bi.bytes_read);
-               comedi_buf_read_free(async, bi.bytes_read);
-
-               if (!(comedi_get_subdevice_runflags(s) & (SRF_ERROR |
-                                       SRF_RUNNING))
-                       && async->buf_write_count == async->buf_read_count) {
-                       do_become_nonbusy(dev, s);
+       if ((s->subdev_flags & SDF_CMD_READ) != 0) {
+               if (bi.bytes_read) {
+                       bi.bytes_read = comedi_buf_read_alloc(async,
+                                       bi.bytes_read);
+                       comedi_buf_read_free(async, bi.bytes_read);
+               }
+               if (async->buf_write_count == async->buf_read_count) {
+                       if (!(comedi_get_subdevice_runflags(s) & (SRF_RUNNING
+                                                       | SRF_ERROR))) {
+                               do_become_nonbusy(dev, s);
+                       }
+                       if (bi.bytes_read == 0) {
+                               if ((comedi_get_subdevice_runflags(s)
+                                               & (SRF_RUNNING | SRF_ERROR))
+                                               == SRF_ERROR) {
+                                       retval = -EPIPE;
+                               }
+                       }
                }
        }
 
-       if (bi.bytes_written && (s->subdev_flags & SDF_CMD_WRITE)) {
-               bi.bytes_written =
-                       comedi_buf_write_alloc(async, bi.bytes_written);
-               comedi_buf_write_free(async, bi.bytes_written);
+       if ((s->subdev_flags & SDF_CMD_WRITE) != 0) {
+               if (bi.bytes_written) {
+                       bi.bytes_written = comedi_buf_write_alloc(async,
+                                       bi.bytes_written);
+                       comedi_buf_write_free(async, bi.bytes_written);
+               }
+               if (bi.bytes_written == 0) {
+                       if (!(comedi_get_subdevice_runflags(s) & SRF_RUNNING)) {
+                               if ((comedi_get_subdevice_runflags(s)
+                                               & SRF_ERROR) != 0) {
+                                       retval = -EPIPE;
+                               }
+                       }
+               }
        }
 
+       if (retval)
+               return retval;
+
+      copyback_position:
        bi.buf_write_count = async->buf_write_count;
        bi.buf_write_ptr = async->buf_write_ptr;
        bi.buf_read_count = async->buf_read_count;