[PATCH 1/1] nvme-fabrics: Generate uevent on namespace AENs

[Christoph Hellwig]

On Fri, Apr 30, 2021 at 09:21:04AM -0700, Keith Busch wrote:
> On Fri, Apr 30, 2021 at 05:14:55AM +0000, Rao, Vinay wrote:
> > + Madhu
> > 
> > Hi Chaitanya, 
> > 
> > Some of the AEN's like ANA state change and Name Space attribute change events are of interest outside the NVME driver. 
> > 
> > It would be good to consider these events to be propagated up to user space. I am not yet convinced on how propagating this above to user space is problematic.
> 
> The namespace attribute change event pairs with the Changed Namespace
> List log, and reading that log will change the result for a subsequent
> reader. User space racing with the kernel on a log access when there are
> read side effects creates non-deterministic behavior, and that is
> problematic.

The only way I could think of making this work is by:

forcing the RAE bit on for all log pages that the kernel cares about,
and only delivering the uevent on controllers that actually do support
the RAE bit (IIRC it got added in 1.3, but I'd have to check).