Re: [PATCH] perf/x86/intel/uncore: Fix iounmap() leak on global_init failure

Chen, Zide
2026-01-14T19:41:07Z

On 1/13/2026 11:51 PM, Markus Elfring wrote:
>>>> If domain->global_init() fails in __parse_discovery_table(), the
>>>> mapped MMIO region is not released before returning, resulting in
>>>> an iounmap() leak.
>>>
>>> How do you think about to avoid a bit of duplicate source code here?
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.19-rc5#n526
>>
>> Thank you for the suggestion!
>>
>> Yes, I agree this is better.
>
> Thanks for this positive feedback.
>
>
>> In V1 I followed the existing style in this API.
>
> This variant might be nicer for backporting.
>
>
>> I will post a v2 with this change:
>>
>> @@ -264,6 +264,7 @@ static int __parse_discovery_table(struct
>> uncore_discovery_domain *domain,
>> struct uncore_unit_discovery unit;
>> void __iomem *io_addr;
>> unsigned long size;
>> + int ret = 0;
>> int i;
>
> Would scope adjustments become helpful for any of these local vartiables?

Yes, I agree that moving int i into the for loop would be better, but
I’d prefer to keep this patch focused and leave that change for future
cleanup.

>
>> size = UNCORE_DISCOVERY_GLOBAL_MAP_SIZE;
>> @@ -273,21 +274,23 @@ static int __parse_discovery_table(struct
> …
>> - if (domain->global_init && domain->global_init(global.ctl))
>> - return -ENODEV;
>> + if (domain->global_init && domain->global_init(global.ctl)) {
>> + ret = -ENODEV;
>> + goto out;
>> + }
> …
>> *parsed = true;
>> +
>> +out:
>
> Would an other label be a bit clearer here?
>
> unmap_io:

It seems that the perf driver generally uses simple labels such as done,
out, or err. Additionally, since there is only a single error path
here, I would prefer to keep the label out for style consistency.

>
>> iounmap(io_addr);
>> - return 0;
>> + return ret;
>> }
>>
>> static int parse_discovery_table(struct uncore_discovery_domain
>>
>>> See also once more:
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.19-rc5#n94
>
> Will another imperative wording become helpful for an improved change description?

Sure, I’ll try my best to improve the description.

>> Are you suggesting that I add a Closes tag?
>
> It depends …
>
>
>> This issue was reported by Intel internal LKP, and there is no public
>> URL available.
>
> Thanks for such a bit of background information.
> Some contributors would appreciate further hints on involved development tools
> (and known source code analysis approaches).

I may add the following report to the commit message for additional context:

Unverified Error/Warning (likely false positive, kindly check if
interested):
arch/x86/events/intel/uncore_discovery.c:293:2-8:
ERROR: missing iounmap; ioremap on line 288 and execution via
conditional on line 292

> Regards,
> Markus