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Date:   Mon, 13 Jul 2020 08:56:14 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>,
        linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Steven Rostedt <rostedt@goodmis.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Alexandre Ghiti <alex@ghiti.fr>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Peter Collingbourne <pcc@google.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH RFC] kprobes: Remove MODULES dependency
Message-ID: <20200713055614.GF956284@linux.intel.com>
References: <20200709234521.194005-1-jarkko.sakkinen@linux.intel.com>
 <20200710193257.4eeb19e9cd042d99cbca7f9a@kernel.org>
 <202007100849.9FA1E414A@keescook>
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On Fri, Jul 10, 2020 at 08:51:56AM -0700, Kees Cook wrote:
> On Fri, Jul 10, 2020 at 07:32:57PM +0900, Masami Hiramatsu wrote:
> > On Fri, 10 Jul 2020 02:45:19 +0300
> > Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote:
> > > +#ifdef CONFIG_MODULES
> > >  	/* Lock modules while optimizing kprobes */
> > >  	mutex_lock(&module_mutex);
> > > +#endif
> > 
> > Hmm, can you reduce these "#ifdef CONFIG_MODULE"s ?
> > 
> > e.g. 
> > 
> > #ifdef CONFIG_MODULES
> > static void lock_modules(void)
> > {
> > 	mutex_lock(&module_mutex);
> > }
> > ...
> > #else
> > #define lock_modules() do { } while (0)
> > ...
> > #endif
> 
> I prefer using "static inline" for no-op functions just because they
> will maintain argument type validation by the compiler regardless of the
> CONFIG state (though it doesn't really matter here since it's void).
> 
> #else
> static inline lock_modules(void) { }
> #endif
> 
> -- 
> Kees Cook

Thanks Kees, good remark.

/Jarkko