On Thu, Nov 25, 2021 at 05:14:23PM +0100, Petr Mladek wrote: > On Tue 2021-11-23 12:23:39, Luis Chamberlain wrote: > > From: Xiaoming Ni <nixiaoming@xxxxxxxxxx> > > > > The kernel/sysctl.c is a kitchen sink where everyone leaves > > their dirty dishes, this makes it very difficult to maintain. > > > > To help with this maintenance let's start by moving sysctls to > > places where they actually belong. The proc sysctl maintainers > > do not want to know what sysctl knobs you wish to add for your own > > piece of code, we just care about the core logic. > > > > Today though folks heavily rely on tables on kernel/sysctl.c so > > they can easily just extend this table with their needed sysctls. > > In order to help users move their sysctls out we need to provide a > > helper which can be used during code initialization. > > > > We special-case the initialization use of register_sysctl() since > > it *is* safe to fail, given all that sysctls do is provide a dynamic > > interface to query or modify at runtime an existing variable. So the > > use case of register_sysctl() on init should *not* stop if the sysctls > > don't end up getting registered. It would be counter productive to > > stop boot if a simple sysctl registration failed. > > > > Provide a helper for init then, and document the recommended init > > levels to use for callers of this routine. We will later use this > > in subsequent patches to start slimming down kernel/sysctl.c tables > > and moving sysctl registration to the code which actually needs > > these sysctls. > > Do we really need a new helper for this? > Is the failure acceptable only during system initialization? Yes because it is __init and we allow / guide folks to *think* clearly about not stopping the init process when it comes to sysctls on failure. > The warning would be useful even for the original register_sysctl(). We can open code those. > It should be up-to-the caller to decide if the failure is fatal > or not. It might be enough to document the reasoning why a warning > is enough in most cases. For most case I have seen so far special casing init seems like a worthy objective. When we're done with the full conversion we can re-visit things but at this point I can't say sharing this outside of init uses makes too much sense. Luis
