On Tue, 30 Jul 2019 15:24:47 -0700, Takshak Chahande wrote: > Having static variable `cpus` in libbpf_num_possible_cpus function without > guarding it with mutex makes this function thread-unsafe. > > If multiple threads accessing this function, in the current form; it > leads to incrementing the static variable value `cpus` in the multiple > of total available CPUs. > > Let caching the number of possile CPUs handled by libbpf's users than > this library itself;
Can we just use stack variable for the calculations and READ_ONCE()/WRITE_ONCE() for assignment to the static? libbpf itself uses this helper so caller caching wouldn't work there. > and let this function be rock bottom one which reads > and parse the file (/sys/devices/system/cpu/possible) everytime it gets > called to simplify the things. I don't understand can you rephrase? > Fixes: 6446b3155521 (bpf: add a new API libbpf_num_possible_cpus()) > No new line after the fixes tag, also I think you're missing quotation marks around the commit title? > Signed-off-by: Takshak Chahande <ctaks...@fb.com> > Acked-by: Andrey Ignatov <r...@fb.com>
