linux-kernel - Re: [PATCH v9 6/7] kgdb: Provide a stub kgdb_nmicallback() if !CONFIG

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Message-ID: <ZNDG9AIdH443Z4BX@FVFF77S0Q05N.cambridge.arm.com>
Date:   Mon, 7 Aug 2023 11:27:00 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Sumit Garg <sumit.garg@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        linux-perf-users@...r.kernel.org, ito-yuichi@...itsu.com,
        Chen-Yu Tsai <wens@...e.org>, Ard Biesheuvel <ardb@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org,
        kgdb-bugreport@...ts.sourceforge.net,
        Masayoshi Mizuma <msys.mizuma@...il.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Lecopzer Chen <lecopzer.chen@...iatek.com>,
        Jason Wessel <jason.wessel@...driver.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 6/7] kgdb: Provide a stub kgdb_nmicallback() if
 !CONFIG_KGDB

On Thu, Jun 01, 2023 at 02:31:50PM -0700, Douglas Anderson wrote:
> To save architectures from needing to wrap the call in #ifdefs, add a
> stub no-op version of kgdb_nmicallback(), which returns 1 if it didn't
> handle anything.
> 
> Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> In v9 this is the only kgdb dependency. I'm assuming it could go
> through the arm64 tree? If that's not a good idea, we could always
> change the patch ("arm64: kgdb: Roundup cpus using IPI as NMI") not to
> depend on it by only calling kgdb_nmicallback() if CONFIG_KGDB is not
> defined.
> 
> Changes in v9:
> - Added missing "inline"
> 
> Changes in v8:
> - "Provide a stub kgdb_nmicallback() if !CONFIG_KGDB" new for v8
> 
>  include/linux/kgdb.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
> index 258cdde8d356..76e891ee9e37 100644
> --- a/include/linux/kgdb.h
> +++ b/include/linux/kgdb.h
> @@ -365,5 +365,6 @@ extern void kgdb_free_init_mem(void);
>  #define dbg_late_init()
>  static inline void kgdb_panic(const char *msg) {}
>  static inline void kgdb_free_init_mem(void) { }
> +static inline int kgdb_nmicallback(int cpu, void *regs) { return 1; }

Is '1' an error?

Can we return an actual error code if so? It makes it *much* clearer to anyone
looking at the code.

Thanks,
Mark.

>  #endif /* ! CONFIG_KGDB */
>  #endif /* _KGDB_H_ */
> -- 
> 2.41.0.rc2.161.g9c6817b8e7-goog
>