19/01/2018 19:13, Ferruh Yigit: > On 1/19/2018 5:54 PM, Thomas Monjalon wrote: > > 19/01/2018 17:19, Ferruh Yigit: > >> On 1/18/2018 6:10 PM, Matan Azrad wrote: > >>> From: Ferruh Yigit, Thursday, January 18, 2018 7:31 PM > >>>> This patch updates *all* ethdev public APIs to add if device is removed > >>>> check? > >>> > >>> Yes. > >>> > >>>> And each check goes to ethdev is_removed() dev_ops to ask if dev is > >>>> removed. > >>> Probably, if the REMOVED state setted in will not call device is_remove. > >>> > >>>> These must be better way of doing this, am I missing something. > >>> > >>> Suggest. > >> > >> With a silly analogy, this is like a blind person asking each time if he > >> is dead > >> before talking to other person. > >> > >> At first glance I can think of a kind of watchdog timer can be implemented > >> in > >> ethdev layer. It provides periodic checks and if device is dead it calls > >> the > >> registered user callback function. > >> > >> This method presented as synchronous method but not triggered from side > >> where > >> event happens, I mean not triggered from PMD but from application. > >> So does application doing polling continuously if device is dead? > >> Or if application is relying this patch to add a check in each API, what > >> happens > >> if device removed during data processing, will app rely on asynchronous > >> method? > > > > We cannot put a mutex on hardware removal :) > > So we have to live with errors du to removal. > > If we are trying to configure a removed device, > > the error will be not related to the root cause. > > This patch is just trying to improve the situation by returning > > an appropriate error code if removal can be detected. > > Note: the check is run only if there is an error > > and if the removal is not already detected. > > > > If I understand well, you prefer relying only on asynchronous > > hotplug events? Even if they come really late? > > I think asynchronous hotplug events are better approach, but if they are late > I > understand you need a solution. > > I assume issue is when device is removed, application can make API calls until > it detects the removal. > > For that case what do you think instead of ethdev abstraction layer doing a > translation, define a specific error type and return it from PMDs to indicate > that error is related to the missing device and application will know device > is > no more there? And consistently use that error type in all PMDs.
Yes it is also a good solution. I think Matan proposed to integrate it in ethdev to avoid duplicating the same mechanism in every PMDs. > Or what do you think above suggested flexible watchdog timer implementation in > ethdev, so applications may be informed about missing device faster. I think the watchdog would compete with hotplug events. So I prefer not integrating one more asynchronous mechanism for the same purpose. If we want polling, it can be an option to enable in EAL hotplug.
