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

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  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

#1323683 — Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init()

On 12/28, Masahiro Yamada wrote:
> The .git_parent is mandatory for multi-parent clocks.  Move the check

s/git/get/

Same for the subject.

> 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.

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

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#1323705 — Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init()

Hi Stephen,



2016-02-02 9:50 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> On 12/28, Masahiro Yamada wrote:
>> The .git_parent is mandatory for multi-parent clocks.  Move the check
>
> s/git/get/
>
> Same for the subject.
>
>> 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().




-- 
Best Regards
Masahiro Yamada

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#1323729

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

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#1323743 — Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init()

2016-02-02 11:39 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> 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.
>

Ah, I missed that.

We need

   ret = -EINVAL;
   goto out;

here, I think.

Shall I send the v3 for 08/16?

Or, if it is too late, shall I send a fix-up patch?




-- 
Best Regards
Masahiro Yamada

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#1324617

On 02/02, Masahiro Yamada wrote:
> 2016-02-02 11:39 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> >
> > 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.
> >
> 
> Ah, I missed that.
> 
> We need
> 
>    ret = -EINVAL;
>    goto out;
> 
> here, I think.
> 
> Shall I send the v3 for 08/16?
> 
> Or, if it is too late, shall I send a fix-up patch?
> 

I'll split the patch out again and squash in those two lines.
Nothing more to do. Thanks.

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

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#1324831 — Re: [RESEND PATCH v2 10/16] clk: move checking .git_parent to __clk_core_init()

Hi Stephen,


2016-02-03 5:43 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> On 02/02, Masahiro Yamada wrote:
>> 2016-02-02 11:39 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
>> >
>> > 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.
>> >
>>
>> Ah, I missed that.
>>
>> We need
>>
>>    ret = -EINVAL;
>>    goto out;
>>
>> here, I think.
>>
>> Shall I send the v3 for 08/16?
>>
>> Or, if it is too late, shall I send a fix-up patch?
>>
>
> I'll split the patch out again and squash in those two lines.
> Nothing more to do. Thanks.


Thank you very much for taking care of all of them!



-- 
Best Regards
Masahiro Yamada

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