Messages in this thread | | | Subject | Re: [PATCH v7 03/15] s390/zcrypt: driver callback to indicate resource in use | From | Tony Krowiak <> | Date | Fri, 24 Apr 2020 13:07:38 -0400 |
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On 4/23/20 11:33 PM, Halil Pasic wrote: > On Thu, 16 Apr 2020 11:37:21 +0200 > Cornelia Huck <cohuck@redhat.com> wrote: > >> On Wed, 15 Apr 2020 13:10:10 -0400 >> Tony Krowiak <akrowiak@linux.ibm.com> wrote: >> >>> On 4/14/20 8:58 AM, Cornelia Huck wrote: >>>> On Tue, 7 Apr 2020 15:20:03 -0400 >>>> Tony Krowiak <akrowiak@linux.ibm.com> wrote: >>>>> + >>>>> + if (ap_drv->in_use) >>>>> + if (ap_drv->in_use(newapm, ap_perms.aqm)) >>>> Can we log the offending apm somewhere, preferably with additional info >>>> that allows the admin to figure out why an error was returned? >>> One of the things on my TODO list is to add logging to the vfio_ap >>> module which will track all significant activity within the device >>> driver. I plan to do that with a patch or set of patches specifically >>> put together for that purpose. Having said that, the best place to >>> log this would be in the in_use callback in the vfio_ap device driver >>> (see next patch) where the APQNs that are in use can be identified. >>> For now, I will log a message to the dmesg log indicating which >>> APQNs are in use by the matrix mdev. >> Sounds reasonable. My main issue was what an admin was supposed to do >> until logging was in place :) > Logging may not be the right answer here. Imagine somebody wants to build > a nice web-tool for managing this stuff at scale -- e.g. something HMC. I > don't think the solution is to let this tool parse the kernel messages > and try to relate that to its own transactions.
I don't believe there is no right or wrong answer here; I simply don't see the relevance of discussing a tool in this context. We are talking about a sysfs attribute interface here, so - correct me if I'm mistaken - our options for notifying the user that a queue is in use are limited to the return code from the sysfs interface and logging. I would expect that a tool would have to do something similar to the callback implemented in the vfio_ap device driver and check the APQNs removed against the APQNs assigned to the mdevs to determine which is in use.
> > But I do agree, having a way to report why "won't do" to the end user is > important for usability. > > Regards, > Halil > >>>> >>>>> + rc = -EADDRINUSE; >>>>> + >>>>> + module_put(drv->owner); >>>>> + >>>>> + return rc; >>>>> +}
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