[PATCH 3.11 28/36] staging: comedi: avoid memleak for subdevice private

Greg Kroah-Hartman
2013-11-26T18:16:17Z

From: Ian Abbott <abbotti@mev.co.uk>

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>

---
drivers/staging/comedi/comedi_fops.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -543,7 +543,7 @@ void *comedi_alloc_spriv(struct comedi_s
{
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_de
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() */