Re: [PATCH v3 3/3] soc: qcom: rtmfs: Handle reserved-memory allocation issues

Bjorn Andersson
2023-09-22T02:40:58Z

On Thu, Sep 21, 2023 at 08:11:23PM +0200, Stephan Gerhold wrote:
> On Wed, Sep 20, 2023 at 07:37:32PM -0700, Bjorn Andersson wrote:
> > In the even that Linux failed to allocate the reserved memory range
> > specified in the DeviceTree, the size of the reserved_mem will be 0,
> > which results in a oops when memory remapping is attempted.
> >
> > Detect this and report that the memory region was not found instead.
> >
> > Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
>
> I dropped these checks in my remoteproc patches because Caleb suggested
> maybe putting this check directly in of_reserved_mem_lookup() (or
> similar) given that almost none of the users verify this [1].
>
> Do you have any opinion on that? I asked back then too but you did not
> reply yet [2]. :-)
>

I'm struggling to come up with a use case where one would like to get
hold of the rmem when it wasn't properly initialized. So, let's make an
attempt at returning NULL from of_reserved_mem_lookup() instead.

Thanks,
Bjorn

> [1]: https://lore.kernel.org/linux-arm-msm/c3f59fb4-4dd8-f27a-d3f5-b1870006a75c@linaro.org/
> [2]: https://lore.kernel.org/linux-arm-msm/ZIsld-MAdkKvdzTx@gerhold.net/
>
> > ---
> > drivers/soc/qcom/rmtfs_mem.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/soc/qcom/rmtfs_mem.c b/drivers/soc/qcom/rmtfs_mem.c
> > index 83bba9321e72..13823abd85c2 100644
> > --- a/drivers/soc/qcom/rmtfs_mem.c
> > +++ b/drivers/soc/qcom/rmtfs_mem.c
> > @@ -180,7 +180,7 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
> > int ret, i;
> >
> > rmem = of_reserved_mem_lookup(node);
> > - if (!rmem) {
> > + if (!rmem || !rmem->size) {
> > dev_err(&pdev->dev, "failed to acquire memory region\n");
> > return -EINVAL;
> > }
> >
> > --
> > 2.25.1
> >