linux-kernel - Re: [PATCH v3 1/5] PM / clock_ops: Add pm_clk_add

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <54492A69.5070505@ti.com>
Date:	Thu, 23 Oct 2014 19:18:49 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:	<ssantosh@...nel.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>,
	<khilman@...aro.org>, <linux-pm@...r.kernel.org>,
	Rob Herring <robh+dt@...nel.org>, <grant.likely@...retlab.ca>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v3 1/5] PM / clock_ops: Add pm_clk_add_clk()

On 10/23/2014 06:49 PM, Dmitry Torokhov wrote:
> On Thu, Oct 23, 2014 at 05:22:58PM +0300, Grygorii Strashko wrote:
>> From: Geert Uytterhoeven <geert+renesas@...der.be>
>>
>> The existing pm_clk_add() allows to pass a clock by con_id. However,
>> when referring to a specific clock from DT, no con_id is available.
>>
>> Add pm_clk_add_clk(), which allows to specify the struct clk * directly.
>>
>> CC: Ulf Hansson <ulf.hansson@...aro.org>
>> CC: Dmitry Torokhov <dmitry.torokhov@...il.com>
>> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@...com>
>> Reviewed-by: Kevin Hilman <khilman@...aro.org>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> ---
>>   drivers/base/power/clock_ops.c | 41 +++++++++++++++++++++++++++++++----------
>>   include/linux/pm_clock.h       |  8 ++++++++
>>   2 files changed, 39 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
>> index 7836930..f14b767 100644
>> --- a/drivers/base/power/clock_ops.c
>> +++ b/drivers/base/power/clock_ops.c
>> @@ -53,7 +53,8 @@ static inline int __pm_clk_enable(struct device *dev, struct clk *clk)
>>    */
>>   static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
>>   {
>> -	ce->clk = clk_get(dev, ce->con_id);
>> +	if (!ce->clk)
>> +		ce->clk = clk_get(dev, ce->con_id);
>>   	if (IS_ERR(ce->clk)) {
>>   		ce->status = PCE_STATUS_ERROR;
>>   	} else {
>> @@ -63,15 +64,8 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
>>   	}
>>   }
>>
>> -/**
>> - * pm_clk_add - Start using a device clock for power management.
>> - * @dev: Device whose clock is going to be used for power management.
>> - * @con_id: Connection ID of the clock.
>> - *
>> - * Add the clock represented by @con_id to the list of clocks used for
>> - * the power management of @dev.
>> - */
>> -int pm_clk_add(struct device *dev, const char *con_id)
>> +static int __pm_clk_add(struct device *dev, const char *con_id,
>> +			struct clk *clk)
>>   {
>>   	struct pm_subsys_data *psd = dev_to_psd(dev);
>>   	struct pm_clock_entry *ce;
>> @@ -93,6 +87,8 @@ int pm_clk_add(struct device *dev, const char *con_id)
>>   			kfree(ce);
>>   			return -ENOMEM;
>>   		}
>> +	} else {
>
> You need __clk_get(clk) here, otherwise when you will be removing clocks
> you'll be dropping a reference that does not belong to you (as yiou have
> not taken it).

No, I don't ;)

pm_clk_add_clk is intended to be used with valid pointer on clk,
which means clk_get() has been called already. In our case:
	clk = of_clk_get(dev->of_node, i));
	ret = pm_clk_add_clk(dev, clk);

It's just a different way to fill list of clocks for device,
once pm_clk_add_clk() is called - PM clock framework will be the owner
of clock.

>
>> +		ce->clk = clk;
>>   	}
>>
>

regards,
-grygorii

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/