staging: comedi: avoid memleak for subdevice private

commit 67aa4acbc97f6a55b328e4e2305ef19cbe949d85 upstream.

`comedi_alloc_spriv()` allocates private storage for a comedi subdevice
and sets the `SRF_FREE_SPRIV` flag in the `runflags` member of the
subdevice to allow the private storage to be automatically freed when
the comedi device is being cleaned up.  Unfortunately, the flag gets
clobbered by `do_cmd_ioctl()` which calls
`comedi_set_subdevice_runflags()` with a mask value `~0` and only the
`SRF_USER` and `SRF_RUNNING` flags set, all the other SRF flags being
cleared.

Change the calls to `comedi_set_subdevice_runflags()` that currently use
a mask value of `~0` to use a more relevant mask value.  For
`do_cmd_ioctl()`, the relevant SRF flags are `SRF_USER`, `SRF_ERROR` and
`SRF_RUNNING`.  (At one time, `SRF_RT` would be included in that set of
flags, but it is no longer used.)  For `comedi_alloc_spriv()` replace
the call to `comedi_set_subdevice_runflags()` with a simple
OR-assignment to avoid unnecessary use of a spin-lock.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 1636c7c..a3af469 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -543,7 +543,7 @@ void *comedi_alloc_spriv(struct comedi_subdevice *s, size_t size)
 {
        s->private = kzalloc(size, GFP_KERNEL);
        if (s->private)
-               comedi_set_subdevice_runflags(s, ~0, SRF_FREE_SPRIV);
+               s->runflags |= SRF_FREE_SPRIV;
        return s->private;
 }
 EXPORT_SYMBOL_GPL(comedi_alloc_spriv);
@@ -1485,7 +1485,8 @@ static int do_cmd_ioctl(struct comedi_device *dev,
        if (async->cmd.flags & TRIG_WAKE_EOS)
                async->cb_mask |= COMEDI_CB_EOS;
 
-       comedi_set_subdevice_runflags(s, ~0, SRF_USER | SRF_RUNNING);
+       comedi_set_subdevice_runflags(s, SRF_USER | SRF_ERROR | SRF_RUNNING,
+                                     SRF_USER | SRF_RUNNING);
 
        /* set s->busy _after_ setting SRF_RUNNING flag to avoid race with
         * comedi_read() or comedi_write() */