linux-kernel - Re: [Patch 1/3] clk: fix clk_mux_get

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Message-ID: <51AD88D2.7060107@ti.com>
Date:	Tue, 4 Jun 2013 11:57:30 +0530
From:	Ambresh K <ambresh@...com>
To:	Mike Turquette <mturquette@...aro.org>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	Tero Kristo <t-kristo@...com>, Rajendra <rnayak@...com>,
	Nishanth Menon <nm@...com>
Subject: Re: [Patch 1/3] clk: fix clk_mux_get_parent return's signed value


> 
> clksel is an omap-centric term.  How about:
> 
> "clk_mux_get_parent should return an error if the value read from the
> register is erroneous."
> 

Make sense, will fix it.   

> The general approach looks good to me.  Can you submit a V2 which
> removes all of the clksel-isms and updates definitions for .get_parent
> functions to avoid the warnings you mentioned in the cover letter?  You
> might find cocinelle useful for that last task.
> 

Thanks! 
Will fix them and add your ack to it? 


> Regards,
> Mike
> 
>> Currently if the value read is greater than the number of
>> available parents clk_mux_get_parent return's signed error
>> which will result in NULL pointer dereferencing in the
>> calling functions.
>>
>> Signed-off-by: Ambresh K <ambresh@...com>
>> ---
>>  drivers/clk/clk-mux.c        |    2 +-
>>  drivers/clk/clk.c            |   12 +++++++++++-
>>  include/linux/clk-provider.h |    4 ++--
>>  3 files changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
>> index 25b1734..be0857e 100644
>> --- a/drivers/clk/clk-mux.c
>> +++ b/drivers/clk/clk-mux.c
>> @@ -29,7 +29,7 @@
>>  
>>  #define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
>>  
>> -static u8 clk_mux_get_parent(struct clk_hw *hw)
>> +static int clk_mux_get_parent(struct clk_hw *hw)
>>  {
>>         struct clk_mux *mux = to_clk_mux(hw);
>>         int num_parents = __clk_get_num_parents(hw->clk);
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 934cfd1..c187321 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -1281,7 +1281,7 @@ EXPORT_SYMBOL_GPL(clk_get_parent);
>>  static struct clk *__clk_init_parent(struct clk *clk)
>>  {
>>         struct clk *ret = NULL;
>> -       u8 index;
>> +       int index;
>>  
>>         /* handle the trivial cases */
>>  
>> @@ -1309,6 +1309,11 @@ static struct clk *__clk_init_parent(struct clk *clk)
>>          */
>>  
>>         index = clk->ops->get_parent(clk->hw);
>> +       if (index < 0) {
>> +               pr_err("%s: clk(%s) invalid parent clk_sel index(%d)\n",
>> +                               __func__, clk->name, index);
>> +               goto out;
>> +       }
>>  
>>         if (!clk->parents)
>>                 clk->parents =
>> @@ -1632,6 +1637,11 @@ int __clk_init(struct device *dev, struct clk *clk)
>>         hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
>>                 if (orphan->ops->get_parent) {
>>                         i = orphan->ops->get_parent(orphan->hw);
>> +                       if (i < 0) {
>> +                               pr_err("%s: orphan clk(%s) invalid parent\n",
>> +                                               __func__, orphan->name);
>> +                               continue;
>> +                       }
>>                         if (!strcmp(clk->name, orphan->parent_names[i]))
>>                                 __clk_reparent(orphan, clk);
>>                         continue;
>> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
>> index 1186098..96337a1 100644
>> --- a/include/linux/clk-provider.h
>> +++ b/include/linux/clk-provider.h
>> @@ -80,7 +80,7 @@ struct clk_hw;
>>   *             supported by the clock.
>>   *
>>   * @get_parent:        Queries the hardware to determine the parent of a clock.  The
>> - *             return value is a u8 which specifies the index corresponding to
>> + *             return value which specifies the index corresponding to
>>   *             the parent clock.  This index can be applied to either the
>>   *             .parent_names or .parents arrays.  In short, this function
>>   *             translates the parent value read from hardware into an array
>> @@ -127,7 +127,7 @@ struct clk_ops {
>>         long            (*round_rate)(struct clk_hw *hw, unsigned long,
>>                                         unsigned long *);
>>         int             (*set_parent)(struct clk_hw *hw, u8 index);
>> -       u8              (*get_parent)(struct clk_hw *hw);
>> +       int             (*get_parent)(struct clk_hw *hw);
>>         int             (*set_rate)(struct clk_hw *hw, unsigned long,
>>                                     unsigned long);
>>         void            (*init)(struct clk_hw *hw);
>> -- 
>> 1.7.4.1
> 
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