Re: [PATCH v4 1/2] clk: hisilicon: Use correct return value about hisi_reset_init()

[Tiezhu Yang]

On 05/29/2020 12:31 PM, Stephen Boyd wrote:
> Quoting Tiezhu Yang (2020-05-28 21:02:05)
> > On 05/29/2020 11:58 AM, Stephen Boyd wrote:
> > > Quoting Tiezhu Yang (2020-05-28 19:03:54)
> > > > On 05/29/2020 07:15 AM, Stephen Boyd wrote:
> > > > > Quoting Tiezhu Yang (2020-05-27 19:27:42)
> > > > > > On 05/28/2020 03:06 AM, Stephen Boyd wrote:
> > > > > > > Quoting Tiezhu Yang (2020-05-27 07:39:21)
> > > > > > > > The return value about hisi_reset_init() is not correct, fix it.
> > > > > > > >
> > > > > > > > Fixes: e9a2310fb689 ("reset: hisilicon: fix potential NULL pointer dereference")
> > > > > > > hisi_reset_init() returns NULL on error in that commit. This patch
> > > > > > > doesn't make sense.
> > > > > > Hi Stephen,
> > > > > >
> > > > > > The initial aim of this patch is to use correct return value about
> > > > > > hisi_reset_init(), maybe NULL is OK, but the return value in this
> > > > > > patch is more accurate.
> > > > > The implementation of hisi_reset_init() that I see is this:
> > > > >
> > > > >
> > > > >         struct hisi_reset_controller *rstc;
> > > > >
> > > > >         rstc = devm_kmalloc(&pdev->dev, sizeof(*rstc), GFP_KERNEL);
> > > > >         if (!rstc)
> > > > >                 return NULL;
> > > > >
> > > > >         rstc->membase = devm_platform_ioremap_resource(pdev, 0);
> > > > >         if (IS_ERR(rstc->membase))
> > > > >                 return NULL;
> > > > >
> > > > >         spin_lock_init(&rstc->lock);
> > > > >         rstc->rcdev.owner = THIS_MODULE;
> > > > >         rstc->rcdev.ops = &hisi_reset_ops;
> > > > >         rstc->rcdev.of_node = pdev->dev.of_node;
> > > > >         rstc->rcdev.of_reset_n_cells = 2;
> > > > >         rstc->rcdev.of_xlate = hisi_reset_of_xlate;
> > > > >         reset_controller_register(&rstc->rcdev);
> > > > >
> > > > >         return rstc;
> > > > >
> > > > > And that returns NULL on an error and a valid pointer on success.
> > > > > Changing the code to check the return value of hisi_reset_init() for an
> > > > > error pointer is simply wrong without updating hisi_reset_init() to
> > > > > return an error pointer on error. Where is the patch that changes
> > > > > hisi_reset_init() to return an error pointer?
> > > > Hi Stephen,
> > > >
> > > > Do you mean the following changes?
> > > Yes where is this change?
> > ERR_PTR(-ENOMEM) and ERR_CAST(rstc->membase)
> I think you didn't understand my question. I'm asking where is this
> patch applied to the kernel and what commit is it? I don't see it in the
> clk tree.

Sorry for that, actually I do not quite understand what you mean.

In my opinion, after the following commit,  when devm_ioremap_resource()
is called in hisi_reset_init(), hisi_reset_init() still returns NULL and 
it only returns
-ENOMEM when call hisi_reset_init() failed, I think it may returns 
-EINVAL, -EBUSY
or -ENOMEM if failed, this is what I want to fix.

"reset: hisilicon: fix potential NULL pointer dereference"
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/commit/drivers/clk/hisilicon/reset.c?h=clk-next&id=e9a2310fb689151166df7fd9971093362d34bd79