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Message-ID: <alpine.DEB.2.20.1702280939090.3153@hadrien>
Date: Tue, 28 Feb 2017 09:44:57 +0100 (CET)
From: Julia Lawall <julia.lawall@...6.fr>
To: Arushi Singhal <arushisinghal19971997@...il.com>
cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
arnaud.patard@...-net.org, devel@...verdev.osuosl.org,
linux-kernel@...r.kernel.org, outreachy-kernel@...glegroups.com
Subject: Re: [Outreachy kernel] Re: [PATCH v6] staging: xgifb: correct the
multiple line dereference
On Tue, 28 Feb 2017, Arushi Singhal wrote:
>
>
> On Tue, Feb 28, 2017 at 11:21 AM, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
> On Tue, Feb 28, 2017 at 10:35:30AM +0530, Arushi Singhal wrote:
> > Error reported by checkpatch.pl as "avoid multiple line dereference".
> > Addition of new variables to make the code more readable and also to
> > correct about mentioned error as by itroducing new variables line is
> > not exceeding 80 characters.
> >
> > Signed-off-by: Arushi Singhal <arushisinghal19971997@...il.com>
> > ---
> > changes in v6
> > - changes done such that no other errors can generate.
> > - Improve the coding style.
> > - Introduced new variables.
> > - type of the variable is changed.
> >
> > drivers/staging/xgifb/XGI_main_26.c | 29 ++++++-----------------------
> > drivers/staging/xgifb/vb_setmode.c | 17 +++++++++++------
> > 2 files changed, 17 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/staging/xgifb/XGI_main_26.c b/drivers/staging/xgifb/XGI_main_26.c
> > index 69ed137337ce..9870ea3b76b4 100644
> > --- a/drivers/staging/xgifb/XGI_main_26.c
> > +++ b/drivers/staging/xgifb/XGI_main_26.c
> > @@ -878,30 +878,13 @@ static void XGIfb_post_setmode(struct xgifb_video_info *xgifb_info)
> > }
> >
> > if ((filter >= 0) && (filter <= 7)) {
> > + const u8 *f = XGI_TV_filter[filter_tb].filter[filter];
> > pr_debug("FilterTable[%d]-%d: %*ph\n",
> > - filter_tb, filter,
> > - 4, XGI_TV_filter[filter_tb].
> > - filter[filter]);
> > - xgifb_reg_set(
> > - XGIPART2,
> > - 0x35,
> > - (XGI_TV_filter[filter_tb].
> > - filter[filter][0]));
> > - xgifb_reg_set(
> > - XGIPART2,
> > - 0x36,
> > - (XGI_TV_filter[filter_tb].
> > - filter[filter][1]));
> > - xgifb_reg_set(
> > - XGIPART2,
> > - 0x37,
> > - (XGI_TV_filter[filter_tb].
> > - filter[filter][2]));
> > - xgifb_reg_set(
> > - XGIPART2,
> > - 0x38,
> > - (XGI_TV_filter[filter_tb].
> > - filter[filter][3]));
> > + filter_tb, filter, 4, f);
> > + xgifb_reg_set(XGIPART2, 0x35, f[0]);
> > + xgifb_reg_set(XGIPART2, 0x36, f[1]);
> > + xgifb_reg_set(XGIPART2, 0x37, f[2]);
> > + xgifb_reg_set(XGIPART2, 0x38, f[3]);
> > }
> > }
> > }
> > diff --git a/drivers/staging/xgifb/vb_setmode.c b/drivers/staging/xgifb/vb_setmode.c
> > index 7c7c8c8f1df3..249a32804c06 100644
> > --- a/drivers/staging/xgifb/vb_setmode.c
> > +++ b/drivers/staging/xgifb/vb_setmode.c
> > @@ -221,8 +221,11 @@ static unsigned char XGI_AjustCRT2Rate(unsigned short ModeIdIndex,
> >
> > for (; XGI330_RefIndex[RefreshRateTableIndex + (*i)].ModeID ==
> > tempbx; (*i)--) {
> > - infoflag = XGI330_RefIndex[RefreshRateTableIndex + (*i)].
> > - Ext_InfoFlag;
> > + unsigned short j;
> > +
> > + j = XGI330_RefIndex[RefreshRateTableIndex + (*i)].Ext_InfoFlag;
> > + infoflag = j;
> > +
> > if (infoflag & tempax)
> > return 1;
>
>
> Why are you using a temporary variable 'j' here? It's not needed at
> all, and just is confusing to read the code now, don't you agree?
>
>
> I am using temporary variable of small size(character) so that when
> I fixed the multiple line dereference then the line number of characters in a line will
> not increase by 80.
I agree with Greg that this is not a readable solution. Putting the whole
thing on one line would be better, even if it goes over 80 characters.
Having the field on a line by itself is much worse, because then it looks
like a variable name - one doesn't easily see the connection to the
structure. Hopefully someone will come up with a shorter name for
RefreshRateTableIndex and then the problem will be completely solved.
Maybe ref_table_index? Although to me ref looks like reference, not
refresh...
julia
>
> > @@ -231,8 +234,11 @@ static unsigned char XGI_AjustCRT2Rate(unsigned short ModeIdIndex,
> > }0
> >
> > for ((*i) = 0;; (*i)++) {
> > - infoflag = XGI330_RefIndex[RefreshRateTableIndex + (*i)].
> > - Ext_InfoFlag;
> > + unsigned short m;
> > +
> > + m = XGI330_RefIndex[RefreshRateTableIndex + (*i)].Ext_InfoFlag;
> > + infoflag = m;
> > +
> > if (XGI330_RefIndex[RefreshRateTableIndex + (*i)].ModeID
> > != tempbx) {
> > return 0;
>
> Same here, why add a new variable that isn't used more than once? You
> are trying to work around something that doesn't make sense to work
> around.
>
> Same reason as above.
> Thanks
> Arushi
>
> Remember, coding style cleanups are to be done to make the code easier
> to understand and follow. Not to blindly follow a perl script that
> can not think. Sometimes it is not right...
>
> thanks,
>
> greg k-h
>
>
>
>
>
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