On Sat, Jan 02, 2021 at 02:25:34PM -0800, Andrii Nakryiko wrote: SNIP > > > > so your .config has > > CONFIG_CRYPTO_DEV_BCM_SPU=y > > > > and that defines 'struct device_private' which > > clashes with the same struct defined in drivers/base/base.h > > > > so several networking structs will be doubled, like net_device: > > > > $ bpftool btf dump file ../vmlinux.config | grep net_device\' | grep STRUCT > > [2731] STRUCT 'net_device' size=2240 vlen=133 > > [113981] STRUCT 'net_device' size=2240 vlen=133 > > > > each is using different 'struct device_private' when it's unwinded > > > > and that will confuse BTFIDS logic, becase we have multiple structs > > with the same name, and we can't be sure which one to pick > > > > perhaps we should check on this in pahole and warn earlier with > > better error message.. I'll check, but I'm not sure if pahole can > > survive another hastab ;-) > > > > Andrii, any ideas on this? ;-) > > It's both unavoidable and correct from the C type system's > perspective, so there is nothing for pahole to warn about. We used to > have (for a long time) a similar clash with two completely different > ring_buffer structs. Eventually they just got renamed to avoid > duplication of related structs (task_struct and tons of other). But > both BTF dedup and CO-RE relocation algorithms are designed to handle > this correctly, ... AFAIU it's all correctly dedulicated, but still all structs that contain (at some point) 'struct device_private' will appear twice in BTF data.. each with different 'struct device_private' > ... so perhaps BTFIDS should be able to handle this as > well? hm, BTFIDS sees BTF data with two same struct names and has no way to tell which one to use unless we have some annotation data for BTF types I don't see a way to handle this correctly.. but I think we can detect this directly in BTFIDS and print more accurate error message as long as we dont see this on daily basis, I think that better error message + following struct rename is good solution > > > > > easy fix is the patch below that renames the bcm's structs, > > it makes the kernel to compile.. but of course the new name > > is probably wrong and we should push this through that code > > authors > > In this case, I think renaming generic device_private name is a good > thing regardless. ok, I'll send the change jirka
