Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1323729

Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init()

Show all headers | View raw

On 02/02, Masahiro Yamada wrote:
> 2016-02-02 9:50 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> > On 12/28, Masahiro Yamada wrote:
> >> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> >> index e6e10f5..4ad0a36 100644
> >> --- a/drivers/clk/clk.c
> >> +++ b/drivers/clk/clk.c
> >> @@ -1677,13 +1677,6 @@ static struct clk_core *__clk_init_parent(struct clk_core *core)
> >>               goto out;
> >>       }
> >>
> >> -     if (!core->ops->get_parent) {
> >> -             WARN(!core->ops->get_parent,
> >> -                     "%s: multi-parent clocks must implement .get_parent\n",
> >> -                     __func__);
> >> -             goto out;
> >> -     }
> >> -
> >>       /*
> >>        * Do our best to cache parent clocks in core->parents.  This prevents
> >>        * unnecessary and expensive lookups.  We don't set core->parent here;
> >> @@ -2315,6 +2308,11 @@ static int __clk_core_init(struct clk_core *core)
> >>               goto out;
> >>       }
> >>
> >> +     if (core->num_parents > 1 && !core->ops->get_parent) {
> >> +             pr_err("%s: %s must implement .get_parent as it has multi parents\n",
> >> +                    __func__, core->name);
> >> +     }
> >> +
> >
> > This would seem to allow a case where we may deref a null
> > get_parent op if it isn't set and we call __clk_init_parent().
> > The next patch removes that case by restructuring
> > __clk_init_parent(), so we should just combine these two patches
> > together and that theoretical problem goes away.
> >
> 
> I think the case never happens.
> 
> __clk_init_parent() is a static function that is only called from
> __clk_core_init().
> So, the null pointer for .get_parent() has been already checked before
> __clk_init_parent().
> 

Right, this patch moves the check to __clk_core_init(), and it
will print an error and then keep going (because we lost the goto
out part). Once we keep going in __clk_core_init() we'll call
__clk_init_parent() and NULL pointer deref.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to  __clk_core_init() Stephen Boyd <sboyd@codeaurora.org> - 2016-02-02 02:00 +0100
  Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-02-02 03:30 +0100
    Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to  __clk_core_init() Stephen Boyd <sboyd@codeaurora.org> - 2016-02-02 03:40 +0100
      Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-02-02 03:50 +0100
        Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to  __clk_core_init() Stephen Boyd <sboyd@codeaurora.org> - 2016-02-02 21:50 +0100
          Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-02-03 03:20 +0100

csiph-web