linux-kernel - Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit

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Date:   Sun, 30 Aug 2020 09:05:13 -0700
From:   Joe Perches <joe@...ches.com>
To:     Denis Efremov <efremov@...ux.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Alex Dewar <alex.dewar90@...il.com>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format
 sysfs output

On Sun, 2020-08-30 at 18:25 +0300, Denis Efremov wrote:
> 
> On 8/30/20 3:43 AM, Joe Perches wrote:
> > $ cat sysfs_emit.cocci
> > @@
> > identifier d_show =~ "^.*show.*$";
> 
> I think this additional pattern will allow to take more functions into the scope. 
> 
> @da@
> identifier show, store;
> expression name, mode;
> @@
> 
> (
>   DEVICE_ATTR(name, mode, show, store)
>   DEVICE_ATTR_PREALLOC(name, mode, show, store)
>   DEVICE_ATTR_IGNORE_LOCKDEP(name, mode, show, store)
> )

Thanks Denis.

I'll try that out too.

A trivial grep shows there are at least 130+
DEVICE_ATTR functions that have a show function
that doesn't include "show" in the function name.

$ grep-2.5.4 -rP --include=*.[ch] '\bDEVICE_ATTR\s*\(\s*\w+\s*,\s*[^,]+,\s*[^,]*,[^;]+;' * | \
  perl -p -e 's/[[:space:]]*//g; s/;/;\n/g' | \
  cut -f3 -d, | \
  grep -v show | \
  sort | uniq | wc -l
139

> @@
> // I think device_show_ulong, device_show_int, device_show_bool
> // functions deserve explicit handling because they are somewhat
> // reference implementations.

Those reference implementations could be send as
a separate patch but this preliminary script does
already handle them.

I do like the idea below of renaming the show
functions without _show in the name adding _show.

> identifier d_show = { da.show, device_show_ulong, device_show_int, device_show_bool };
> identifier dev, attr, buf;
> @@
> 
> * ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
>   {
>      ...
>   }
> 
> 
> I tried also to handle DEVICE_ATTR_RW, but I failed to use fresh identifier.
> This doesn't work:
> 
> @darw@
> identifier name;
> @@
> 
> (
>   DEVICE_ATTR_RW(name)
>   DEVICE_ATTR_RO(name)
>   DEVICE_ATTR_WO(name)
> )
> 
> @@
> identifier darw.name;
> fresh identifier d_show = name ## "_show"; // <== parse error
> identifier dev, attr, buf;
> @@
> 
> * ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
>   {
>      ...
>   }
> 
> 
> Regards,
> Denis