Re: [PATCH] modpost: check for static EXPORT_SYMBOL* functions

Denis Efremov
2019-07-29T09:16:33Z

> Just a reminder that some of us (just me?) do well over 100+ builds per
> day ... if this can be optimised some what that would be good.

These measurements for the worst case (allmodconfig). Is it possible to
measure the slowdown in your case? How it will perform on your typical
workflow?

Looks like it is possible to optimize it, but I need some hints from
Masahiro on how to do it properly. Because I don't know how to match
__ksymtab_<symbol> with the <symbol> without an additional loop.
Introduce another hash table?

The first loop from this patch could traverse only the exported symbols
instead of all symbols. But in this case, I don't know how to break
early from the loop because there can be many symbols with the same name
but with the different scope (static/non-static).

For example, ring_buffer_size:
kernel/trace/ring_buffer.c
4334:unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu)
4347:EXPORT_SYMBOL_GPL(ring_buffer_size);
And
drivers/usb/misc/ldusb.c
125:static int ring_buffer_size = 128;

Or for, nfs4_disable_idmapping:
fs/nfs/super.c
2920:bool nfs4_disable_idmapping = true;
2930:EXPORT_SYMBOL_GPL(nfs4_disable_idmapping);
fs/nfsd/nfs4idmap.c
48:static bool nfs4_disable_idmapping = true;

Regards,
Denis