On April 18, 2019 12:49:00 AM GMT+09:00, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > On Wed, Apr 17, 2019 at 03:15:31PM +0200, Matteo Croce wrote: > > In the sysctl code the proc_dointvec_minmax() function is often used > to > > validate the user supplied value between an allowed range. This > function > > uses the extra1 and extra2 members from struct ctl_table as minimum > and > > maximum allowed value. > > > > On sysctl handler declaration, in every source file there are some > readonly > > variables containing just an integer which address is assigned to > the > > extra1 and extra2 members, so the sysctl range is enforced. > > > > The special values 0, 1 and INT_MAX are very often used as range > boundary, > > leading duplication of variables like zero=0, one=1, int_max=INT_MAX > in > > different source files: > > > > $ git grep -E '\.extra[12].*&(zero|one|int_max)\b' |wc -l > > 245 > > > > This patch adds three const variables for the most commonly used > values, > > and use them instead of creating a local one for every object file. > > Does this actually cause the kernel size to shrink? EXPORT_SYMBOL > isn't > free, you know. Hi Matthew, In this case we have three __kstrtab_ symbols of size 11,12 and 15, and a bunch of u32 removed, so the size should shrink anyway. I will try to calculate the exact saving with bloat-o-meter. Regards, -- Matteo Croce per aspera ad upstream
