Re: [PATCH 1/1] nvme-fabrics: Generate uevent on namespace AENs
From: Hannes Reinecke <hare@suse.de>
Date: 2021-06-24 09:10:33
On 5/3/21 8:52 AM, Christoph Hellwig wrote:
On Fri, Apr 30, 2021 at 09:21:04AM -0700, Keith Busch wrote:quoted
On Fri, Apr 30, 2021 at 05:14:55AM +0000, Rao, Vinay wrote:quoted
+ 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).
Yep, that sounds like a good idea. I would even go so far as to inhibit any user-space commands which read those log pages and which have the RAE bit _not_ set, as this has the potential of messing up the kernel operations... Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Felix Imendörffer _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme