linux-kernel - Re: [PATCH resent] perf/x86/amd/uncore: Fix exception handling in amd_uncore_cpu_up

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Date:   Mon, 27 Mar 2023 16:58:13 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Markus Elfring <Markus.Elfring@....de>,
        kernel-janitors@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ian Rogers <irogers@...gle.com>,
        Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sandipan Das <sandipan.das@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Zhouyi Zhou <zhouzhouyi@...il.com>, x86@...nel.org,
        cocci@...ia.fr, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH resent] perf/x86/amd/uncore: Fix exception handling in
 amd_uncore_cpu_up_prepare()

On Mon, Mar 27, 2023 at 12:11:54PM +0300, Adrian Hunter wrote:
> On 25/03/23 16:15, Markus Elfring wrote:
> > Date: Fri, 17 Mar 2023 13:13:14 +0100
> > 
> > The label “fail” was used to jump to another pointer check despite of
> > the detail in the implementation of the function “amd_uncore_cpu_up_prepare”
> > that it was determined already that the corresponding variable contained
> > a null pointer (because of a failed function call in two cases).
> > 
> > 1. Thus return directly after a call of the function “amd_uncore_alloc”
> >    failed in the first if branch.
> > 
> > 2. Use more appropriate labels instead.
> > 
> > 3. Reorder jump targets at the end.
> > 
> > 4. Delete a redundant check and kfree() call.
> > 
> > 5. Omit an explicit initialisation for the local variable “uncore_llc”.
> > 
> > 
> > This issue was detected by using the Coccinelle software.
> > 
> > Fixes: 39621c5808f5dda75d03dc4b2d4d2b13a5a1c34b ("perf/x86/amd/uncore: Use dynamic events array")
> > Fixes: 503d3291a937b726757c1f7c45fa02389d2f4324 ("perf/x86/amd: Try to fix some mem allocation failure handling")
> 
> Commit should be only the first 12 characters of the hash.
> Refer:	https://docs.kernel.org/process/submitting-patches.html
> 
> But this is not a fix. Redundant calls to kfree do not break
> anything.
> 
> Also avoid using the term "exception" since, in x86, exceptions are
> hardware events.  Better to just call it "error handling".

Don't feed the trolls; Markus is a bot or other weird construct that's
been banned from lkml.