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

From: Tiezhu Yang
Date: Fri May 29 2020 - 02:44:29 EST


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