Re: [PATCH v3] checkpatch.pl: New instances of ENOSYS are errors

[Joe Perches <joe@perches.com>]

On Fri, 2014-08-22 at 11:05 -0700, Andy Lutomirski wrote:
> ENOSYS means that a nonexistent system call was called.  We have a
> bad habit of using it for things like invalid operations on
> otherwise valid syscalls.  We should avoid this in new code.

Seems sensible thanks for persisting.

Andrew Morton is generally the upstream path (cc'd)

> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
> ---
> 
> Pervasive incorrect usage of ENOSYS came up at the kernel summit ABI
> review discussion.  Let's see if checkpatch can help.
> 
> I'll submit a separate patch for include/uapi/asm-generic/errno.h.
> 
> Changes from v2:
>  - Reduce severity to WARN.
>  - Remove unnecessary clarification.
>  - Rebase onto Linus' tree instead of v3.16.
> 
> Changes from v1:
>  - Moved later so that it won't warn on context lines.
>  - Use $herecur.
>  - Improve regex pattern.
> 
>  scripts/checkpatch.pl | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 31a731e..448d075 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -3214,6 +3214,14 @@ sub process {
>  			     "Prefer dev_$level(... to dev_printk(KERN_$orig, ...\n" . $herecurr);
>  		}
>  
> +# ENOSYS means "bad syscall nr" and nothing else.  This will have a small
> +# number of false positives, but assembly files are not checked, so at
> +# least the arch entry code will not trigger this warning.
> +		if ($line =~ /\bENOSYS\b/) {
> +			WARN("ENOSYS",
> +			     "ENOSYS means 'invalid syscall nr' and nothing else\n" . $herecurr);
> +		}
> +
>  # function brace can't be on same line, except for #defines of do while,
>  # or if closed on same line
>  		if (($line=~/$Type\s*$Ident\(.*\).*\s*{/) and