linux-kernel - Re: [V2] perf/x86/intel/uncore: Fix iounmap() leak on global

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Message-ID: <00565b33-c47d-4529-9590-56f93ab45d10@web.de>
Date: Fri, 16 Jan 2026 18:30:18 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: Chen Zide <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>, Namhyung Kim <namhyung@...nel.org>,
 Peter Zijlstra <peterz@...radead.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: [V2] perf/x86/intel/uncore: Fix iounmap() leak on global_init
 failure

…
>> 3. Which text part of your change description does contain “orders to
>>    the codebase to change its behaviour”?
> 
> OK, I see your point. Yes, it's good to add one sentence to describe
> what the patches does.

I became curious somehow if further contributors would be willing to care
a bit more also for this wording requirement.


>                        But I guess this patch is simple enough.

But it seems that several technical details triggered special communication challenges.


> I don’t think this change alone justifies a separate patch, as it would
> add review overhead without providing much practical benefit.

Will any other contributors dare to add related insights?


>> The corresponding change recombination can occasionally become more interesting
>> for selected development ideas.
> 
> 
> Are you suggesting putting this into a separate patch?

Yes.

I propose a stricter distinction between a “quick” fix and subsequent refinements
at the discussed source code places.


> My impression is that the change is simple and closely related, though I
> may be missing something. I understand others may see it differently.

It seems that we are struggling according to recurring factors of change resistance.


> @@ -273,21 +274,23 @@ static int __parse_discovery_table(struct
> uncore_discovery_domain *domain,
> 
>         /* Read Global Discovery State */
>         memcpy_fromio(&global, io_addr, sizeof(struct
> uncore_global_discovery));
> +       iounmap(io_addr);
> +
>         if (uncore_discovery_invalid_unit(global)) {
>                 pr_info("Invalid Global Discovery State: 0x%llx 0x%llx
> 0x%llx\n",
>                         global.table1, global.ctl, global.table3);
> -               iounmap(io_addr);
>                 return -EINVAL;
>         }
> -       iounmap(io_addr);


Regards,
Markus