Re: [PATCH 1/1] device core: Add flag to autoremove device link on supplier unbind

[Vivek Gautam]

Hi Rafael,


On 5/30/2018 4:29 PM, Rafael J. Wysocki wrote:
> On 5/30/2018 11:57 AM, Vivek Gautam wrote:
> > When using the device links without the consumers or
> > suppliers maintaining pointers to these links, a flag can
> > help in autoremoving the links on supplier driver unbind.
> > We remove these links only when the supplier's link to its
> > consumers has gone in DL_STATE_SUPPLIER_UNBIND state.
> >
> > Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
> > Suggested-by: Lukas Wunner <lukas@xxxxxxxxx>
> > ---
> >
> > Lukas, as suggested in the thread [1] this change adds additional flag
> > to autoremove device links on supplier unbind.
> > For arm-smmu, we want to _not_ keep references to the device links
> > added between arm-smmu, and consumer devices.
> > Robin also pointed to [2] the need to autoremove the device link on
> > supplier unbind rather than consumer unbind.
>
> Please CC device links patches to linux-pm.

Thanks for the quick review. Sure, will keep this noted from now on.

> > [1] https://lkml.org/lkml/2018/3/14/390
> > [2] https://lkml.org/lkml/2018/5/21/381
> >
> > Â drivers/base/core.cÂÂÂ | 10 ++++++++++
> > Â include/linux/device.h |Â 2 ++
> > Â 2 files changed, 12 insertions(+)
> >
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index b610816eb887..52c7222bb3c4 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -490,6 +490,16 @@ void device_links_driver_cleanup(struct device 
> > *dev)
> > Â ÂÂÂÂÂÂÂÂÂ WARN_ON(link->flags & DL_FLAG_AUTOREMOVE);
> > ÂÂÂÂÂÂÂÂÂ WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
> > +
> > +ÂÂÂÂÂÂÂ /*
> > +ÂÂÂÂÂÂÂÂ * autoremove the links between this @dev and its consumer
> > +ÂÂÂÂÂÂÂÂ * devices that are not active, i.e. where the link state
> > +ÂÂÂÂÂÂÂÂ * has moved to DL_STATE_SUPPLIER_UNBIND.
> > +ÂÂÂÂÂÂÂÂ */
> > +ÂÂÂÂÂÂÂ if (link->status == DL_STATE_SUPPLIER_UNBIND &&
> > +ÂÂÂÂÂÂÂÂÂÂÂ link->flags & DL_FLAG_AUTOREMOVE_S)
> > +ÂÂÂÂÂÂÂÂÂÂÂ kref_put(&link->kref, __device_link_del);
> > +
> > ÂÂÂÂÂÂÂÂÂ WRITE_ONCE(link->status, DL_STATE_DORMANT);
> > ÂÂÂÂÂ }
> > Â diff --git a/include/linux/device.h b/include/linux/device.h
> > index 477956990f5e..6033bf58453d 100644
> > --- a/include/linux/device.h
> > +++ b/include/linux/device.h
> > @@ -779,11 +779,13 @@ enum device_link_state {
> > ÂÂ * AUTOREMOVE: Remove this link automatically on consumer driver 
> > unbind.
> > ÂÂ * PM_RUNTIME: If set, the runtime PM framework will use this link.
> > ÂÂ * RPM_ACTIVE: Run pm_runtime_get_sync() on the supplier during 
> > link creation.
> > + * AUTOREMOVE_S: Remove this link automatically on supplier driver 
> > unbind.
> > ÂÂ */
> > Â #define DL_FLAG_STATELESSÂÂÂ BIT(0)
> > Â #define DL_FLAG_AUTOREMOVEÂÂÂ BIT(1)
> > Â #define DL_FLAG_PM_RUNTIMEÂÂÂ BIT(2)
> > Â #define DL_FLAG_RPM_ACTIVEÂÂÂ BIT(3)
> > +#define DL_FLAG_AUTOREMOVE_SÂÂÂ BIT(4)
>
> Couldn't you invent a better name for this one?

Frankly, I wanted to have something like DL_FLAG_AUTOREMOVE_SUPPLIER, 
but that
felt a bit too long considering other flags.
Can you please consider suggesting a concise name?

Regards
Vivek
> > Â Â /**
> > ÂÂ * struct device_link - Device link representation.