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Subject: Re: [PATCH v4 06/16] dyndbg: fix a BUG_ON in ddebug_describe_flags
To:     Jim Cromie <jim.cromie@gmail.com>, linux-kernel@vger.kernel.org,
        akpm@linuxfoundation.org
Cc:     gregkh@linuxfoundation.org, linux@rasmusvillemoes.dk,
        kbuild test robot <lkp@intel.com>
References: <20191210022742.822686-1-jim.cromie@gmail.com>
 <20191210022742.822686-7-jim.cromie@gmail.com>
From:   Jason Baron <jbaron@akamai.com>
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Date:   Tue, 10 Dec 2019 14:58:07 -0500
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On 12/9/19 9:27 PM, Jim Cromie wrote:
> ddebug_describe_flags currently fills a caller provided string buffer,
> after testing its size (also passed) in a BUG_ON.  Fix this with a
> struct containing a known-big-enough string buffer, and passing it
> instead.
> 
> Also simplify ddebug_describe_flags sig, and de-ref the struct in the
> caller; this makes function reusable (soon) in contexts where flags
> are already unpacked.
> 
> -v3 fix compile err introduced in patchset grooming.
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  lib/dynamic_debug.c | 31 +++++++++++++++----------------
>  1 file changed, 15 insertions(+), 16 deletions(-)
> 
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index b5fb0aa0fbc3..49cb24948e12 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -62,6 +62,8 @@ struct ddebug_iter {
>  	unsigned int idx;
>  };
>  
> +struct flagsbuf { char buf[12]; };	/* big enough to hold all the flags */


ARRAY_SIZE(opt_array) + 1

max number of flags + string termination.