Messages in this thread | | | Date | Mon, 19 May 2014 13:34:17 -0500 | Subject | Re: [PATCH] PM / OPP: Implement free_opp_table function | From | Nishanth Menon <> |
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On Mon, May 19, 2014 at 1:08 PM, Inderpal Singh <inderpal.s@samsung.com> wrote: > Hi Nishanth, > > Thanks for the review comments. > > On Mon, May 19, 2014 at 6:43 PM, Nishanth Menon <nm@ti.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@samsung.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 :).
>> 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.
Regards, Nishanth Menon
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