Re: [RFC PATCH bpf-next v2 4/4] error-injection: Support fault injection framework

[Alexei Starovoitov]

On Tue, Dec 26, 2017 at 04:48:25PM +0900, Masami Hiramatsu wrote:
> Support in-kernel fault-injection framework via debugfs.
> This allows you to inject a conditional error to specified
> function using debugfs interfaces.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> ---
>  Documentation/fault-injection/fault-injection.txt |    5 +
>  kernel/Makefile                                   |    1 
>  kernel/fail_function.c                            |  169 +++++++++++++++++++++
>  lib/Kconfig.debug                                 |   10 +
>  4 files changed, 185 insertions(+)
>  create mode 100644 kernel/fail_function.c
> 
> diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt
> index 918972babcd8..6243a588dd71 100644
> --- a/Documentation/fault-injection/fault-injection.txt
> +++ b/Documentation/fault-injection/fault-injection.txt
> @@ -30,6 +30,11 @@ o fail_mmc_request
>    injects MMC data errors on devices permitted by setting
>    debugfs entries under /sys/kernel/debug/mmc0/fail_mmc_request
>  
> +o fail_function
> +
> +  injects error return on specific functions by setting debugfs entries
> +  under /sys/kernel/debug/fail_function. No boot option supported.

I like it.
Could you document it a bit better?
In particular retval is configurable, but without an example no one
will be able to figure out how to use it.

I think you can drop RFC tag from the next version of these patches.
Thanks!