As the large array of sysctls in kernel/sysctl.c is reduced we get to the point of wanting to optimize how we register sysctls by only dealing with flat simple structures, with no subdirectories. In particular the last empty element should not be needed. We'll get there, and save some memory, but as we move forward that path will be come the more relevant path to use in the sysctl registration. It is much simpler as it avoids recursion. Turns out we can also convert existing users of register_sysctl_table() which just need their subdirectories created for them. This effort addresses most users of register_sysctl_table() in drivers/ except parport -- that needs a bit more review. This is part of the process to deprecate older sysctl users which uses APIs which can incur recursion, but don't need it [0]. This is the second effort. Yes -- we'll get to the point *each* of these conversions means saving one empty syctl, but that change needs a bit more careful review before merging. But since these conversion are also deleting tables for subdirectories, the delta in size of the kernel should not incrase really. The most complex change is the sgi-xp change which does deal with a case where we have a subdirectory with an entry, I just split that in two registrations. No point in keeping recursion just for a few minor if we can simplify code around. More eyeballs / review / testing on that change is appreciated. Sending these out early so they can get tested properly early on linux-next. I'm happy to take these via sysctl-next [0] but since I don' think register_sysctl_table() will be nuked on v6.4 I think it's fine for each of these to go into each respective tree. I can pick up last stragglers on sysctl-next. If you want me to take this via sysctl-next too, just let me know and I'm happy to do that. Either way works. [0] https://lkml.kernel.org/r/20230302202826.776286-1-mcgrof@xxxxxxxxxx Luis Chamberlain (7): scsi: simplify sysctl registration with register_sysctl() ipmi: simplify sysctl registration hv: simplify sysctl registration md: simplify sysctl registration sgi-xp: simplify sysctl registration tty: simplify sysctl registration xen: simplify sysctl registration for balloon drivers/char/ipmi/ipmi_poweroff.c | 16 +--------------- drivers/hv/vmbus_drv.c | 11 +---------- drivers/md/md.c | 22 +--------------------- drivers/misc/sgi-xp/xpc_main.c | 24 ++++++++++-------------- drivers/scsi/scsi_sysctl.c | 16 +--------------- drivers/tty/tty_io.c | 20 +------------------- drivers/xen/balloon.c | 20 +------------------- 7 files changed, 16 insertions(+), 113 deletions(-) -- 2.39.1
