linux-kernel - Re: [PATCH 02/16] treewide: rename match_string() -> __match

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Message-ID: <7309540.OPNIuQxnsW@phil>
Date:   Thu, 09 May 2019 11:02:23 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, andriy.shevchenko@...ux.intel.com
Subject: Re: [PATCH 02/16] treewide: rename match_string() -> __match_string()

Am Mittwoch, 8. Mai 2019, 19:00:06 CEST schrieb Stephen Boyd:
> (Trimming the lists but keeping lkml)
> 
> Quoting Alexandru Ardelean (2019-05-08 04:28:28)
> > This change does a rename of match_string() -> __match_string().
> > 
> > There are a few parts to the intention here (with this change):
> > 1. Align with sysfs_match_string()/__sysfs_match_string()
> > 2. This helps to group users of `match_string()` into simple users:
> >    a. those that use ARRAY_SIZE(_a) to specify the number of elements
> >    b. those that use -1 to pass a NULL terminated array of strings
> >    c. special users, which (after eliminating 1 & 2) are not that many
> > 3. The final intent is to fix match_string()/__match_string() which is
> >    slightly broken, in the sense that passing -1 or a positive value does
> >    not make any difference: the iteration will stop at the first NULL
> >    element.
> > 
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > ---
> [...]
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index 96053a96fe2f..0b6c3d300411 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -2305,8 +2305,8 @@ bool clk_has_parent(struct clk *clk, struct clk *parent)
> >         if (core->parent == parent_core)
> >                 return true;
> >  
> > -       return match_string(core->parent_names, core->num_parents,
> > -                           parent_core->name) >= 0;
> > +       return __match_string(core->parent_names, core->num_parents,
> > +                             parent_core->name) >= 0;
> 
> This is essentially ARRAY_SIZE(core->parent_names) so it should be fine
> to put this back to match_string() later in the series.
> 
> >  }
> >  EXPORT_SYMBOL_GPL(clk_has_parent);
> >  
> > diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
> > index c3ad92965823..373f13e9cd83 100644
> > --- a/drivers/clk/rockchip/clk.c
> > +++ b/drivers/clk/rockchip/clk.c
> > @@ -276,8 +276,8 @@ static struct clk *rockchip_clk_register_frac_branch(
> >                 struct clk *mux_clk;
> >                 int ret;
> >  
> > -               frac->mux_frac_idx = match_string(child->parent_names,
> > -                                                 child->num_parents, name);
> > +               frac->mux_frac_idx = __match_string(child->parent_names,
> > +                                                   child->num_parents, name);
> 
> I suspect this is the same as above, but Heiko can ack/confirm.

Right now, clock-driver do carry the parent_names in static arrays,
but that isn't necessarily guaranteed. So only in the driver declaring
the array do we use ARRAY_SIZE to determine the number of elements
(from inside the helper-macros in drivers/clk/rockchip/clk.h), but the
rest of the code does explicitly carry around the real number of elements
so later clocks could in theory also do that dynamically.


Heiko