On Wed, 7 Mar 2018 15:34:24 -0500 Waiman Long <longman@xxxxxxxxxx> wrote: > This patch series is to be applied on top of the patch > series "ipc: Clamp *mni to the real IPCMNI limit" > (https://lkml.org/lkml/2018/3/1/716). > > The purpose of this patch series is to enable easy addition of new > auxillary sysctl parameters that can be read to display ranges of > other sysctl parameters they are associated with. > > With this patch series applied, a developer can add a range-showing > auxillary sysctl entries by just setting the CTL_FLAGS_SHOW_RANGE > flag in the ctl_table entry that has a range to show and add one more > to the number of reserved range entries in the CTL_RESERVE_RANGES() > macro before the terminating null entry. The new auxillary sysctl > parameters will have the "_range" suffix added. > > The number of ctl_table entries that have the CTL_FLAGS_SHOW_RANGE flag > should match the number of reserved entries in the CTL_RESERVE_RANGES() > macro. Otherwise, warning or error like below will be logged in the > kernel ring buffer. > > Warning: Too many reserved ctl_table range entries ("shmmax")! > > Error: Insufficient reserved ctl_table range entries ("shmmax")! > > The IPC sysctl parameters msgmni and shmmni are extended to have > those auxillary sysctl entries. As a result, one can now find out > the range of allowable value by looking at the corresponding > auxillary _range sysctl parameters. For example, > > % cat msgmni_range > [0, 32768] > > That means the msgmni sysctl parameter has to be within the 0 - 32768 > range inclusively. > > ... > > fs/proc/proc_sysctl.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++--- > include/linux/sysctl.h | 52 +++++++++++++++++++++++++- > ipc/ipc_sysctl.c | 5 ++- > kernel/sysctl.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 238 insertions(+), 9 deletions(-) That quite a bunch of new code and it's not clear to me that we get a lot of value from it all. Perhaps I'm missing the point. A worked example would help, along the lines of: a) Here's how we do X at present and here's the output b) Here's how we X after these patches and here's the new output c) b) is better than a) for <reasons>
