| Message ID | 1530600642-25090-4-git-send-email-kernelfans@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | drivers/base: bugfix for supplier<-consumer ordering in device_kset | expand |
On Tuesday, July 3, 2018 8:50:41 AM CEST Pingfan Liu wrote: > Clean up the referring to the code in commit 52cdbdd49853 ("driver core: > correct device's shutdown order"). So later we can revert it safely. > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Cc: Grygorii Strashko <grygorii.strashko@ti.com> > Cc: Christoph Hellwig <hch@infradead.org> > Cc: Bjorn Helgaas <helgaas@kernel.org> > Cc: Dave Young <dyoung@redhat.com> > Cc: linux-pci@vger.kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > --- > drivers/base/core.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 684b994..db3deb8 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -127,13 +127,6 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) > { > struct device_link *link; > > - /* > - * Devices that have not been registered yet will be put to the ends > - * of the lists during the registration, so skip them here. > - */ > - if (device_is_registered(dev)) > - devices_kset_move_last(dev); > - > if (device_pm_initialized(dev)) > device_pm_move_last(dev); You can't do this. If you do it, that will break power management in some situations. Thanks, Rafael
On Tue, Jul 3, 2018 at 10:28 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > On Tuesday, July 3, 2018 8:50:41 AM CEST Pingfan Liu wrote: > > Clean up the referring to the code in commit 52cdbdd49853 ("driver core: > > correct device's shutdown order"). So later we can revert it safely. > > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Cc: Grygorii Strashko <grygorii.strashko@ti.com> > > Cc: Christoph Hellwig <hch@infradead.org> > > Cc: Bjorn Helgaas <helgaas@kernel.org> > > Cc: Dave Young <dyoung@redhat.com> > > Cc: linux-pci@vger.kernel.org > > Cc: linuxppc-dev@lists.ozlabs.org > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > > --- > > drivers/base/core.c | 7 ------- > > 1 file changed, 7 deletions(-) > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > index 684b994..db3deb8 100644 > > --- a/drivers/base/core.c > > +++ b/drivers/base/core.c > > @@ -127,13 +127,6 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) > > { > > struct device_link *link; > > > > - /* > > - * Devices that have not been registered yet will be put to the ends > > - * of the lists during the registration, so skip them here. > > - */ > > - if (device_is_registered(dev)) > > - devices_kset_move_last(dev); > > - > > if (device_pm_initialized(dev)) > > device_pm_move_last(dev); > > You can't do this. > > If you do it, that will break power management in some situations. > Could you shed light on it? I had a quick browsing of pm code, but it is a big function, and I got lost in it. If the above code causes failure, then does it imply that the seq in devices_kset should be the same as dpm_list? But in device_shutdown(), it only intersect with pm by pm_runtime_get_noresume(dev) and pm_runtime_barrier(dev). How do these function affect the seq in dpm_list? Need your help to see how to handle this issue. Thanks and regards, Pingfan
On Wednesday, July 4, 2018 6:40:09 AM CEST Pingfan Liu wrote: > On Tue, Jul 3, 2018 at 10:28 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > > > On Tuesday, July 3, 2018 8:50:41 AM CEST Pingfan Liu wrote: > > > Clean up the referring to the code in commit 52cdbdd49853 ("driver core: > > > correct device's shutdown order"). So later we can revert it safely. > > > > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > Cc: Grygorii Strashko <grygorii.strashko@ti.com> > > > Cc: Christoph Hellwig <hch@infradead.org> > > > Cc: Bjorn Helgaas <helgaas@kernel.org> > > > Cc: Dave Young <dyoung@redhat.com> > > > Cc: linux-pci@vger.kernel.org > > > Cc: linuxppc-dev@lists.ozlabs.org > > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > > > --- > > > drivers/base/core.c | 7 ------- > > > 1 file changed, 7 deletions(-) > > > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > > index 684b994..db3deb8 100644 > > > --- a/drivers/base/core.c > > > +++ b/drivers/base/core.c > > > @@ -127,13 +127,6 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) > > > { > > > struct device_link *link; > > > > > > - /* > > > - * Devices that have not been registered yet will be put to the ends > > > - * of the lists during the registration, so skip them here. > > > - */ > > > - if (device_is_registered(dev)) > > > - devices_kset_move_last(dev); > > > - > > > if (device_pm_initialized(dev)) > > > device_pm_move_last(dev); > > > > You can't do this. > > > > If you do it, that will break power management in some situations. > > > Could you shed light on it? I had a quick browsing of pm code, but it > is a big function, and I got lost in it. > If the above code causes failure, then does it imply that the seq in > devices_kset should be the same as dpm_list? Generally, yes it should. > But in device_shutdown(), it only intersect with pm by > pm_runtime_get_noresume(dev) and pm_runtime_barrier(dev). How do these > function affect the seq in dpm_list? They are not related to dpm_list directly. However, if you shut down a supplier device before its consumer and that involves power management, then the consumer shutdown may fail and lock up the system I asked you elsewhere to clearly describe the problem you are trying to address. Please do that in the first place. Thanks, Rafael
On Wed, Jul 4, 2018 at 6:18 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > On Wednesday, July 4, 2018 6:40:09 AM CEST Pingfan Liu wrote: > > On Tue, Jul 3, 2018 at 10:28 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > > > > > On Tuesday, July 3, 2018 8:50:41 AM CEST Pingfan Liu wrote: > > > > Clean up the referring to the code in commit 52cdbdd49853 ("driver core: > > > > correct device's shutdown order"). So later we can revert it safely. > > > > > > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > Cc: Grygorii Strashko <grygorii.strashko@ti.com> > > > > Cc: Christoph Hellwig <hch@infradead.org> > > > > Cc: Bjorn Helgaas <helgaas@kernel.org> > > > > Cc: Dave Young <dyoung@redhat.com> > > > > Cc: linux-pci@vger.kernel.org > > > > Cc: linuxppc-dev@lists.ozlabs.org > > > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > > > > --- > > > > drivers/base/core.c | 7 ------- > > > > 1 file changed, 7 deletions(-) > > > > > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > > > index 684b994..db3deb8 100644 > > > > --- a/drivers/base/core.c > > > > +++ b/drivers/base/core.c > > > > @@ -127,13 +127,6 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) > > > > { > > > > struct device_link *link; > > > > > > > > - /* > > > > - * Devices that have not been registered yet will be put to the ends > > > > - * of the lists during the registration, so skip them here. > > > > - */ > > > > - if (device_is_registered(dev)) > > > > - devices_kset_move_last(dev); > > > > - > > > > if (device_pm_initialized(dev)) > > > > device_pm_move_last(dev); > > > > > > You can't do this. > > > > > > If you do it, that will break power management in some situations. > > > > > Could you shed light on it? I had a quick browsing of pm code, but it > > is a big function, and I got lost in it. > > If the above code causes failure, then does it imply that the seq in > > devices_kset should be the same as dpm_list? > > Generally, yes it should. > > > But in device_shutdown(), it only intersect with pm by > > pm_runtime_get_noresume(dev) and pm_runtime_barrier(dev). How do these > > function affect the seq in dpm_list? > > They are not related to dpm_list directly. > > However, if you shut down a supplier device before its consumer and that > involves power management, then the consumer shutdown may fail and lock up > the system > Ah, get your point. The patch in this series "[PATCHv3 2/4] drivers/base: utilize device tree info to shutdown devices" still obey the shutdown order "parent<-child" and "supplier<-consumer". It just utilizes device-tree info to achieve this, since it turns out not easy to maintain such order in devices_kset. As I described in the commit log of [2/4], it needs two nested recursion, and should consider the breakage of devices_kset's spinlock. > I asked you elsewhere to clearly describe the problem you are trying to > address. Please do that in the first place. > OK, I will reply your question in [0/4] Thanks, Pingfan
diff --git a/drivers/base/core.c b/drivers/base/core.c index 684b994..db3deb8 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -127,13 +127,6 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) { struct device_link *link; - /* - * Devices that have not been registered yet will be put to the ends - * of the lists during the registration, so skip them here. - */ - if (device_is_registered(dev)) - devices_kset_move_last(dev); - if (device_pm_initialized(dev)) device_pm_move_last(dev);
Clean up the referring to the code in commit 52cdbdd49853 ("driver core: correct device's shutdown order"). So later we can revert it safely. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Grygorii Strashko <grygorii.strashko@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Bjorn Helgaas <helgaas@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: linux-pci@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Pingfan Liu <kernelfans@gmail.com> --- drivers/base/core.c | 7 ------- 1 file changed, 7 deletions(-)