On Friday, September 23, 2016 03:50:02 PM Lukas Wunner wrote: > On Fri, Sep 23, 2016 at 02:49:20PM +0200, Rafael J. Wysocki wrote: > > On Tuesday, September 20, 2016 10:51:13 AM Marek Szyprowski wrote: > > > On 2016-09-19 23:45, Tobias Jakobi wrote: > > > > I did some tests with the new version today. Sadly the reboot/shutdown > > > > issues are still present. > > > > > > Thanks for the report. I've managed to reproduce this issue and it is again > > > caused by modifying device on devices_kset list before it will be finally > > > added by device_add(). I thought that the new patchset allows creating > > > links to a device, which has not been yet added to system device list. > > Hm, Marek, why isn't it possible to set up the links from the consumer's > ->probe hook in this case? > > > > > Should it be allowed to create a link to device, which > > > has not yet been added to system device list by device_add()? > > > > While it would be easy to require both the consumer and producer devices to > > be registered for creating a link between them, that would just make it > > harder to use links in the first place. > > > > So ideally, it should be possible to create links between devices before > > registering them, but since I didn't take that into account in the current > > patch series, some quite substantial changes are needed to cover that. > > > > Additional link states come to mind, but then the "stateless" links are > > affected by this problem too. > > device_link_add() could be changed to call device_reorder_to_tail() > only if device_is_registered(consumer) returns true. > > That's an inline function defined in <linux/device.h> which returns > dev->kobj.state_in_sysfs, a flag which is set in kobject_add(). I know what that function is, but using it alone is not sufficient, because dev->kobj.state_in_sysfs is set before the device is added to dpm_list. > Then device_add() would have to check if any links are already > set up and reorder the consumer behind the suppliers. > > Doesn't seem to be *that* complex, but probably I'm missing something, > this is just off the cuff... There are some cases to consider and some races to avoid AFAICS. It all gets a lot simpler if device_link_add() is allowed to return NULL when the supplier device passed to it has not been registered yet. That looks like a reasonable thing to do to me, but I wonder if someone has a use case in which it would be a substantial limitation. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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