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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Mon, 5 Feb 2018 22:21:06 +0100
Message-ID: <CAK8P3a3MMwRQ00YxuPhEmNzqiMn4+VX48b82831i+kCqruCMfQ@mail.gmail.com>
Subject: Re: [tip:x86/urgent] x86/dumpstack: Avoid uninitlized variable
To:     Ingo Molnar <mingo@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Nicolas Pitre <nico@linaro.org>, Arnd Bergmann <arnd@arndb.de>,
        Vlastimil Babka <vbabka@suse.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, bpetkov@suse.de,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Andi Kleen <ak@linux.intel.com>
Cc:     linux-tip-commits@vger.kernel.org
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On Fri, Feb 2, 2018 at 11:36 PM, tip-bot for Arnd Bergmann
<tipbot@zytor.com> wrote:
> Commit-ID:  ebfc15019cfa72496c674ffcb0b8ef10790dcddc
> Gitweb:     https://git.kernel.org/tip/ebfc15019cfa72496c674ffcb0b8ef10790dcddc
> Author:     Arnd Bergmann <arnd@arndb.de>
> AuthorDate: Fri, 2 Feb 2018 15:56:17 +0100
> Committer:  Thomas Gleixner <tglx@linutronix.de>
> CommitDate: Fri, 2 Feb 2018 23:33:50 +0100
>
> x86/dumpstack: Avoid uninitlized variable
>
> In some configurations, 'partial' does not get initialized, as shown by
> this gcc-8 warning:
>
> arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl':
> arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>     show_regs_if_on_stack(&stack_info, regs, partial);
>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> This initializes it to false, to get the previous behavior in this case.
>
> Fixes: a9cdbe72c4e8 ("x86/dumpstack: Fix partial register dumps")


I just noticed my annotation got lost when I sent the patch. I originally
meant to ask Josh to double-check whether it should be 'false' or 'true'
here, or if we maybe need a larger change.

Josh, could you take a look? Unfortunately I did not really understand
your original commit, so I don't know what the safe choice is here
in those cases in which 'partial' is uninitialized.

       Arnd