From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Menon Subject: Re: [PATCH -next] PM / OPP: using kfree_rcu() to simplify the code Date: Fri, 26 Oct 2012 19:14:25 -0500 Message-ID: <20121027001425.GA28617@kahuna> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:43245 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934312Ab2J0AOn (ORCPT ); Fri, 26 Oct 2012 20:14:43 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Wei Yongjun , Vincent Guittot Cc: len.brown@intel.com, pavel@ucw.cz, rjw@sisk.pl, gregkh@linuxfoundation.org, yongjun_wei@trendmicro.com.cn, linux-pm@vger.kernel.org On 22:57-20121026, Wei Yongjun wrote: > From: Wei Yongjun > > The callback function of call_rcu() just calls a kfree(), so we > can use kfree_rcu() instead of call_rcu() + callback function. > > dpatch engine is used to auto generate this patch. > (https://github.com/weiyj/dpatch) > > Signed-off-by: Wei Yongjun > --- > drivers/base/power/opp.c | 13 +------------ > 1 file changed, 1 insertion(+), 12 deletions(-) > > diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c > index c8a908b..50b2831 100644 > --- a/drivers/base/power/opp.c > +++ b/drivers/base/power/opp.c > @@ -461,17 +461,6 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) > } > > /** > - * opp_free_rcu() - helper to clear the struct opp when grace period has > - * elapsed without blocking the the caller of opp_set_availability > - */ > -static void opp_free_rcu(struct rcu_head *head) > -{ > - struct opp *opp = container_of(head, struct opp, head); > - > - kfree(opp); > -} > - > -/** > * opp_set_availability() - helper to set the availability of an opp > * @dev: device for which we do this operation > * @freq: OPP frequency to modify availability > @@ -542,7 +531,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq, > > list_replace_rcu(&opp->node, &new_opp->node); > mutex_unlock(&dev_opp_list_lock); > - call_rcu(&opp->head, opp_free_rcu); > + kfree_rcu(opp, head); > > /* Notify the change of the OPP availability */ > if (availability_req) A good idea. thanks. I wonder if we might squash this with https://patchwork.kernel.org/patch/1504361/ on a side note: struct opp { struct list_head node; bool available; unsigned long rate; unsigned long u_volt; struct device_opp *dev_opp; struct rcu_head; }; we could move rcu_head to the top of the struct .. just to avoid revisiting this at a later point in time *if* struct opp expands.. If we are squashing it, we might consider fixing the kern-doc for "head".. -- Regards, Nishanth Menon