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References: <20240422-kgdb_read_refactor-v2-0-ed51f7d145fe@linaro.org> <20240422-kgdb_read_refactor-v2-6-ed51f7d145fe@linaro.org>
In-Reply-To: <20240422-kgdb_read_refactor-v2-6-ed51f7d145fe@linaro.org>
From: Doug Anderson <dianders@chromium.org>
Date: Mon, 22 Apr 2024 16:52:39 -0700
Message-ID: <CAD=FV=WpHKRGdtnRpq+Bxj0CYX3wUvYV0OmRe0V=zMwVn1AHTQ@mail.gmail.com>
Subject: Re: [PATCH v2 6/7] kdb: Replace double memcpy() with memmove() in kdb_read()
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>, kgdb-bugreport@lists.sourceforge.net, 
	linux-kernel@vger.kernel.org
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Hi,

On Mon, Apr 22, 2024 at 9:38=E2=80=AFAM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> At several points in kdb_read() there are variants of the following
> code pattern (with offsets slightly altered):
>
>     memcpy(tmpbuffer, cp, lastchar - cp);
>     memcpy(cp-1, tmpbuffer, lastchar - cp);
>     *(--lastchar) =3D '\0';
>
> There is no need to use tmpbuffer here, since we can use memmove() instea=
d
> so refactor in the obvious way. Additionally the strings that are being
> copied are already properly terminated so let's also change the code so
> that the library calls also move the terminator.
>
> Changing how the terminators are managed has no functional effect for now
> but might allow us to retire lastchar at a later point. lastchar, althoug=
h
> stored as a pointer, is functionally equivalent to caching strlen(buffer)=
.
>
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
>  kernel/debug/kdb/kdb_io.c | 19 +++++++------------
>  1 file changed, 7 insertions(+), 12 deletions(-)

Reviewed-by: Douglas Anderson <dianders@chromium.org>