linux-kernel - Re: [PATCH] perf/x86/intel/uncore: Fix iounmap() leak on global

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Message-ID: <77078fe5-23fa-4278-b32f-f655f0760be1@web.de>
Date: Wed, 14 Jan 2026 08:51:02 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: Zide Chen <zide.chen@...el.com>, linux-perf-users@...r.kernel.org,
 Adrian Hunter <adrian.hunter@...el.com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Andi Kleen <ak@...ux.intel.com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
 Dapeng Mi <dapeng1.mi@...ux.intel.com>, Ian Rogers <irogers@...gle.com>,
 Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 Namhyung Kim <namhyung@...nel.org>, Stephane Eranian <eranian@...gle.com>
Cc: lkp@...el.com, LKML <linux-kernel@...r.kernel.org>,
 kernel-janitors@...r.kernel.org, Thomas Falcon <thomas.falcon@...el.com>,
 Xudong Hao <xudong.hao@...el.com>
Subject: Re: [PATCH] perf/x86/intel/uncore: Fix iounmap() leak on global_init
 failure

>>> 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?



>         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:


>         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?


> 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).

Regards,
Markus