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From:   "=?ISO-8859-15?B?/YCAgISB?=" <jbi.octave@gmail.com>
Date:   Mon, 1 Jun 2020 23:01:15 +0100 (BST)
To:     Steven Rostedt <rostedt@goodmis.org>
cc:     Jules Irenge <jbi.octave@gmail.com>, linux-kernel@vger.kernel.org,
        tglx@linutronix.de, paulmck@kernel.org, mingo@redhat.com,
        boqun.feng@gmail.com, Borislav Petkov <bp@alien8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 4/5] x86/ftrace: Add annotations for ftrace_arch_code_modify_prepare()
 and ftrace_arch_code_modify_post_process()
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References: <20200601184552.23128-1-jbi.octave@gmail.com> <20200601184552.23128-5-jbi.octave@gmail.com> <20200601154647.581fa345@oasis.local.home>
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On Mon, 1 Jun 2020, Steven Rostedt wrote:

> On Mon,  1 Jun 2020 19:45:51 +0100
> Jules Irenge <jbi.octave@gmail.com> wrote:
>
>> Sparse reports warnings
>>
>> warning: context imbalance in ftrace_arch_code_modify_prepare()
>> 	- wrong count at exit
>> warning: context imbalance in ftrace_arch_code_modify_post_process()
>> 	- wrong count at exit
>>
>> The root cause is that even if
>>  the annotations on the function are correct,
>> mutex do not support annotation
>> This makes Sparse to complain.
>> To fix this,
>> __acquire(&text_mutex) and
>>  __release(&text_mutex) annotations are added
>> inside ftrace_arch_code_modify_prepare()
>> and ftrace_arch_code_modify_post_process()
>> respectively.
>
> Wait what? This looks like either a bug in sparse, or we just remove the
> annotations. This just makes the code ugly, and looks silly.
>
> Nack!
>
> -- Steve
>
>
>
Thanks for the feedback, I take good note.
Jules