When will your kernel issue be fixed ?
Understanding how bugs actually get fixed and fixes get propagated through the kernel is important to understanding when and how your specific issue may be fixed upstream. It should also help you as a user understand why using bleeding edge can tend to help accelerate the pace for a bug fix.
Getting fixes in to wireless-testing first
cfg80211, mac80211, or wireless driver bugs will always be fixed first on the wireless-testing git tree. Once a bug is fixed there it will be determined by the developer and community whether the fix is also required for older stable kernel releases, if it is it will undergo the process described below.
Getting fixes in to stable kernel releases
If a patch submitted for inclusion into wireless-testing is a stable fix candidate the patch will be annotated as such prior to submission with a note towards the bottom of the patch commit log for stable:
Once the patch gets merged onto John's tree, John Linville (wireless maintainer) will determine whether or not the patch also fixes an issue on Linus' tree; and if so it gets submitted to David Miller (networking maintainer) so that David can then propagate the fix to Linus. Once the patch gets merged onto Linus' tree an e-mail will be sent to email@example.com and the patch will be either directly queued or ported for review on the stable-review mailing list. If no objections are raised the patch then gets merged onto the respective stable kernels.
Getting the fix in your Linux distribution
Linux distributions which make official tagged release stick to a series of stable kernels for each release. This is contrary to rolling distributions which always just keep on the latest and greatest all the time. Distributions like Ubuntu, Debian, RHEL, Fedora are not rolling distributions, distributions like Gentoo and Arch are rolling distributions. Non-rolling distributions usually stick to supporting only one kernel per tagged release. The kernel they pick for use on a release is based on the date of the targeted release. Updates to the kernel will be made on a Linux distribution once a new stable kernel release with a newer extraversion is released. The extraversion is the last number in a 4 series number release, so in 18.104.22.168 the extraversion would be 2.
When a fix cannot be propagated to stable releases
Not all fixes will be propagated to stable releases of the Linux kernel. It is better to understand what fixes will be merged onto stable kernel releases than to consider which fixes will not. Fixes which will be accepted for stable kernel releases will vary but a general rule of thumb is:
- Kernel oops
- Security flaws
- Memory leaks
- Regressions (issues introduced into newer kernels which did not exist in older kernel releases)
- Critical fixes
What fits into a Critical fix category are left to the judgment of the subsystem maintainer. Unfortunately for users the reality of this model is some minor fixes which can help a user out on a stable kernel will not be merged into new stable kernel release, but this is also why new kernels are always encouraged, and also why we have come up with bleeding edge compat-wireless releases and stable compat-wireless releases.