Re: [PATCH] error.3: ATTRIBUTES: Note functions that are/aren't thread-safe

["Michael Kerrisk (man-pages)" <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 06/24/2015 11:28 AM, Zeng Linggang wrote:
> The markings match glibc markings.
> markings of functions in glibc are:
> - error:         MT-Safe locale
> - error_at_line: MT-Unsafe race:error_at_line/error_one_per_line locale
> 
> Signed-off-by: Zeng Linggang <zenglg.jy-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>


Hi, Zeng Linggang. 

I'm having some trouble understanding the text you've added. Could you review
and resubmit, please? See below.

> ---
>  man3/error.3 | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/man3/error.3 b/man3/error.3
> index 7e1d47c..f040a26 100644
> --- a/man3/error.3
> +++ b/man3/error.3
> @@ -118,6 +118,35 @@ is assigned the address of a function
>  instead of prefixing the message with the program name and colon.
>  The function should print a suitable string to
>  .IR stderr .
> +.SH ATTRIBUTES
> +For an explanation of the terms used in this section, see
> +.BR attributes (7).
> +.TS
> +allbox;
> +lb lb lbw37
> +l l l.
> +Interface	Attribute	Value
> +T{
> +.BR error ()
> +T}	Thread safety	MT-Safe locale
> +T{
> +.BR error_at_line ()
> +T}	Thread safety	T{
> +MT-Unsafe race:error_at_line/error_one_per_line locale
> +T}
> +.TE
> +
> +The internal
> +.I error_one_per_line
> +variable is accessed (without any form of
> +synchronization, but since it's an int used once, it should be safe
> +enough) and, if this mode is enabled, static variables used to hold

What does "this mode" refer to? That needs to be made clearer in
the text.

> +the last printed file name and line number are accessed and modified
> +without synchronization; the update is not atomic and it occurs
> +before disabling cancellation, so it can be interrupted after only
> +one of the two variables is modified.  After that, it's very much

What does "it" (in "it's") refer to? error_at_line()? 
That needs to be made clearer in the text.

> +like
> +.BR error (3).
>  .SH CONFORMING TO
>  These functions and variables are GNU extensions, and should not be
>  used in programs intended to be portable.

Thanks,

Michael



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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