A General Notification Queue Was Pushed Back From Linux 5.5 Introduction

Red Hat has been working on a "general notification queue" that is built off the Linux kernel's pipe code and will notify the user-space of events like key/keyring changes, block layer events like disk errors, USB attach/remove events, and other notifications without user-space having to continually poll kernel interfaces. This general notification queue was proposed for Linux 5.5 but has been pushed back to at least 5.6.

This Linux kernel general notification queue builds off a standard pipe and allows user-space applications to efficiently become aware of changes to block devices (disks), keys, USB subsystem happenings, and other possible events. The proposed documentation spells out more of the planned functionality and behavior.

This general notification queue can be used for a variety of possible use-cases as laid out via the pull request and more options would come as other areas of the kernel hook into this reporting mechanism.

But Linus Torvalds announced on Thursday that this notification queue isn't ready for Linux 5.5. He's not pulling it due to "something" (still being evaluated / debugged around Btrfs problems) issues going on with the proposed pipe changes. At least it looks like this interesting work stands good chances of being merged in 2020.