From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eduardo Valentin Subject: Re: [PATCH V4 13/13] Thermal: Introduce locking for cdev.thermal_instances list. Date: Tue, 21 Aug 2012 08:01:21 +0300 Message-ID: <20120821050121.GT9833@besouro> References: <1343292083-2047-1-git-send-email-rui.zhang@intel.com> <1343292083-2047-14-git-send-email-rui.zhang@intel.com> <20120820154518.GB9833@besouro> <1345510407.1682.930.camel@rui.sh.intel.com> Reply-To: eduardo.valentin@ti.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from na3sys009aog132.obsmtp.com ([74.125.149.250]:36734 "EHLO na3sys009aog132.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902Ab2HUFBb (ORCPT ); Tue, 21 Aug 2012 01:01:31 -0400 Received: by weyu54 with SMTP id u54so5546443wey.17 for ; Mon, 20 Aug 2012 22:01:27 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1345510407.1682.930.camel@rui.sh.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhang Rui Cc: eduardo.valentin@ti.com, "Rafael J. Wysocki" , Matthew Garrett , Len Brown , R Durgadoss , Amit Kachhap , Wei Ni , linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org Hello, On Tue, Aug 21, 2012 at 08:53:27AM +0800, Zhang Rui wrote: > On =E4=B8=80, 2012-08-20 at 18:45 +0300, Eduardo Valentin wrote: > > Hello Rui, > >=20 > > On Thu, Jul 26, 2012 at 04:41:23PM +0800, Zhang Rui wrote: > > > we need to go over all the thermal_instance list of a cooling dev= ice > > > to decide which cooling state to put the cooling device to. > > >=20 > > > But at this time, as a cooling device may be referenced in multip= le > > > thermal zones, we need to lock the list first in case > > > another thermal zone is updating this cooling device. > > >=20 > > > Signed-off-by: Zhang Rui > >=20 > > Reviewed-by: Eduardo Valentin > >=20 > > A minor comment bellow. > >=20 > > > --- > > > drivers/thermal/thermal_sys.c | 8 ++++++++ > > > include/linux/thermal.h | 1 + > > > 2 files changed, 9 insertions(+) > > >=20 > > > diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/ther= mal_sys.c > > > index 7f3a891..356a59d 100644 > > > --- a/drivers/thermal/thermal_sys.c > > > +++ b/drivers/thermal/thermal_sys.c > > > @@ -799,6 +799,7 @@ int thermal_zone_bind_cooling_device(struct t= hermal_zone_device *tz, > > > goto remove_symbol_link; > > > =20 > > > mutex_lock(&tz->lock); > > > + mutex_lock(&cdev->lock); > >=20 > > Why do you need to lock while going through the tz thermal_instance= s? > >=20 > > > list_for_each_entry(pos, &tz->thermal_instances, tz_node) > > > if (pos->tz =3D=3D tz && pos->trip =3D=3D trip && pos->cdev= =3D=3D cdev) { > > > result =3D -EEXIST; > > > @@ -808,6 +809,7 @@ int thermal_zone_bind_cooling_device(struct t= hermal_zone_device *tz, > > > list_add_tail(&dev->tz_node, &tz->thermal_instances); > > > list_add_tail(&dev->cdev_node, &cdev->thermal_instances); > >=20 > > Locking the above operation should be enough, no? > >=20 > we need to add this thermal_instance to the cooling device > thermal_instance list. > say, what if another thermal zone that references this cooling device= is > being unregistered at the same time? Well yes, that part I got it. But do you need to lock the cdev->lock while doing the search under tz->thermal_instances? I believe you need to lock it only while adding it to cdev->thermal_ins= tances. That would cover the situation you are talking about. >=20 > thanks, > rui >=20 > > > } > > > + mutex_unlock(&cdev->lock); > > > mutex_unlock(&tz->lock); > > > =20 > > > if (!result) > > > @@ -840,14 +842,17 @@ int thermal_zone_unbind_cooling_device(stru= ct thermal_zone_device *tz, > > > struct thermal_instance *pos, *next; > > > =20 > > > mutex_lock(&tz->lock); > > > + mutex_lock(&cdev->lock); > > > list_for_each_entry_safe(pos, next, &tz->thermal_instances, tz_= node) { > > > if (pos->tz =3D=3D tz && pos->trip =3D=3D trip && pos->cdev =3D= =3D cdev) { > > > list_del(&pos->tz_node); > > > list_del(&pos->cdev_node); > > > + mutex_unlock(&cdev->lock); > > > mutex_unlock(&tz->lock); > > > goto unbind; > > > } > > > } > > > + mutex_unlock(&cdev->lock); > > > mutex_unlock(&tz->lock); > > > =20 > > > return -ENODEV; > > > @@ -913,6 +918,7 @@ thermal_cooling_device_register(char *type, v= oid *devdata, > > > } > > > =20 > > > strcpy(cdev->type, type); > > > + mutex_init(&cdev->lock); > > > INIT_LIST_HEAD(&cdev->thermal_instances); > > > cdev->ops =3D ops; > > > cdev->updated =3D true; > > > @@ -1016,6 +1022,7 @@ static void thermal_cdev_do_update(struct t= hermal_cooling_device *cdev) > > > if (cdev->updated) > > > return; > > > =20 > > > + mutex_lock(&cdev->lock); > > > /* Make sure cdev enters the deepest cooling state */ > > > list_for_each_entry(instance, &cdev->thermal_instances, cdev_no= de) { > > > if (instance->target =3D=3D THERMAL_NO_TARGET) > > > @@ -1023,6 +1030,7 @@ static void thermal_cdev_do_update(struct t= hermal_cooling_device *cdev) > > > if (instance->target > target) > > > target =3D instance->target; > > > } > > > + mutex_unlock(&cdev->lock); > > > cdev->ops->set_cur_state(cdev, target); > > > cdev->updated =3D true; > > > } > > > diff --git a/include/linux/thermal.h b/include/linux/thermal.h > > > index 06fd04d..d02d06d 100644 > > > --- a/include/linux/thermal.h > > > +++ b/include/linux/thermal.h > > > @@ -95,6 +95,7 @@ struct thermal_cooling_device { > > > void *devdata; > > > const struct thermal_cooling_device_ops *ops; > > > bool updated; /* true if the cooling device does not need updat= e */ > > > + struct mutex lock; /* protect thermal_instances list */ > > > struct list_head thermal_instances; > > > struct list_head node; > > > }; > > > --=20 > > > 1.7.9.5 > > >=20 >=20 >=20 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html