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Date: Tue, 20 May 2014 11:06:30 +0530 From: Inderpal Singh <inderpal.s@...sung.com> To: Nishanth Menon <nm@...com> Cc: "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Pavel Machek <pavel@....cz>, Viresh Kumar <viresh.kumar@...aro.org> Subject: Re: [PATCH] PM / OPP: Implement free_opp_table function On Tue, May 20, 2014 at 12:04 AM, Nishanth Menon <nm@...com> wrote: > On Mon, May 19, 2014 at 1:08 PM, Inderpal Singh <inderpal.s@...sung.com> wrote: >> Hi Nishanth, >> >> Thanks for the review comments. >> >> On Mon, May 19, 2014 at 6:43 PM, Nishanth Menon <nm@...com> wrote: >>> On 05/16/2014 04:09 AM, Inderpal Singh wrote: >>>> At the driver unloading time the associated opp table may need >>>> to be deleted. Otherwise it amounts to memory leak. The existing >>>> OPP library does not have provison to do so. >>>> >>>> Hence this patch implements the function to free the opp table. >>>> >>>> Signed-off-by: Inderpal Singh <inderpal.s@...sung.com> >>>> --- >>>> drivers/base/power/opp.c | 41 +++++++++++++++++++++++++++++++++++++++++ >>>> include/linux/pm_opp.h | 6 ++++++ >>>> 2 files changed, 47 insertions(+) >>>> >>>> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c >>>> index d9e376a..d45ffd5 100644 >>>> --- a/drivers/base/power/opp.c >>>> +++ b/drivers/base/power/opp.c >>>> @@ -654,4 +654,45 @@ int of_init_opp_table(struct device *dev) >>>> return 0; >>>> } >>>> EXPORT_SYMBOL_GPL(of_init_opp_table); >>>> + >>>> +/** >>>> + * dev_pm_opp_free_opp_table() - free the opp table >>>> + * @dev: device for which we do this operation >>>> + * >>>> + * Free up the allocated opp table >>>> + * >>>> + * Locking: The internal device_opp and opp structures are RCU protected. >>>> + * Hence this function internally uses RCU updater strategy with mutex locks to >>>> + * keep the integrity of the internal data structures. Callers should ensure >>>> + * that this function is *NOT* called under RCU protection or in contexts where >>>> + * mutex locking or synchronize_rcu() blocking calls cannot be used. >>>> + */ >>>> +void dev_pm_opp_free_opp_table(struct device *dev) >>>> +{ >>>> + struct device_opp *dev_opp = NULL; >>>> + struct dev_pm_opp *opp; >>>> + >>> if (!dev) >>> return; >>> >> >> missed it. Will take care in the next version. >> >>>> + /* Hold our list modification lock here */ >>>> + mutex_lock(&dev_opp_list_lock); >>>> + >>>> + /* Check for existing list for 'dev' */ >>>> + dev_opp = find_device_opp(dev); >>>> + if (IS_ERR(dev_opp)) { >>>> + mutex_unlock(&dev_opp_list_lock); >>>> + return; >>>> + } >>>> + >>>> + while (!list_empty(&dev_opp->opp_list)) { >>>> + opp = list_entry_rcu(dev_opp->opp_list.next, >>>> + struct dev_pm_opp, node); >>>> + list_del_rcu(&opp->node); >>>> + kfree_rcu(opp, head); >>>> + } >>> >>> How about the OPP notifiers? should'nt we add a new event >>> OPP_EVENT_REMOVE? >>> >> >> As this function is to free the whole opp table. Hence, I think, >> notifier may not be needed. It may be required for per opp removal as >> is the case with opp addition and enable/disable. But at present there >> are no users of these notifiers at all. Let me know your view. > > umm.. we do have devfreq which depends on OPPs :). Yes, devfreq does depend on OPPs, but no devfreq driver is registering its notifier_block to handle OPP notifications. > >>> To maintain non-dt behavior coherency, should'nt we rather add a >>> opp_remove or an opp_del function? >> >> Yes we should have opp_remove as well, but what's the use case ? >> Should we go ahead and implement it Or, wait for the use-case? > > IMHO, if we are doing it properly, we should add the requisite > function as well. we dont want to have differing behavior device tree > Vs non-DT. So we will have 2 functions then. One to remove the whole opp table and the the other to remove the individual OPPs. I will cover this in v2. Will also take care of the OPP_EVENT_REMOVE notification part. Regards, Inder > > Regards, > Nishanth Menon > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/
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