[PATCH 1/2] coresight: stm: Remove redundant NULL checks

[Leo Yan]

On Thu, Jun 12, 2025 at 09:28:42AM +0100, Mike Leach wrote:
> On Thu, 12 Jun 2025 at 06:19, Anshuman Khandual
> <anshuman.khandual at arm.com> wrote:
> >
> >
> >
> > On 11/06/25 8:14 PM, Leo Yan wrote:
> > > container_of() cannot return NULL, so the checks for NULL pointers are
> > > unnecessary and can be safely removed.
> > >
> > > As a result, this commit silences the following smatch warnings:
> > >
> > >   coresight-stm.c:345 stm_generic_link() warn: can 'drvdata' even be NULL?
> > >   coresight-stm.c:356 stm_generic_unlink() warn: can 'drvdata' even be NULL?
> > >   coresight-stm.c:387 stm_generic_set_options() warn: can 'drvdata' even be NULL?
> > >   coresight-stm.c:422 stm_generic_packet() warn: can 'drvdata' even be NULL?
> > >
> > > Signed-off-by: Leo Yan <leo.yan at arm.com>
> > > ---
> > >  drivers/hwtracing/coresight/coresight-stm.c | 8 ++++----
> > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> > > index e45c6c7204b4491e0f879bc7d5d445aa1d3118be..464b0c85c3f7d3519169d62a51e9f8c6281b5358 100644
> > > --- a/drivers/hwtracing/coresight/coresight-stm.c
> > > +++ b/drivers/hwtracing/coresight/coresight-stm.c
> > > @@ -342,7 +342,7 @@ static int stm_generic_link(struct stm_data *stm_data,
> > >  {
> > >       struct stm_drvdata *drvdata = container_of(stm_data,
> > >                                                  struct stm_drvdata, stm);
> > > -     if (!drvdata || !drvdata->csdev)
> > > +     if (!drvdata->csdev)
> > >               return -EINVAL;

> I'd agree that the container_of() cannot return NULL, but what happens
> if stm_data is NULL?
> Perhaps the NULL check was on the wrong parameter?

The pointer "stm_data" should be safe.  The data structure is allocated
in probe and released in the remove, the structure "stm_data" is safely
accessed during runtime.

If stm_data really has NULL pointer issue, we should already receive
alarms for kernel oops :)

Thanks,
Leo