Consider the following own goal I just discovered I scored:
[~] zgrep -i fq_codel /proc/config.gz
CONFIG_NET_SCH_FQ_CODEL=m
CONFIG_DEFAULT_FQ_CODEL=y
CONFIG_DEFAULT_NET_SCH="fq_codel"
Obviously, fq_codel didn't get set as the default, because that happens
before the module gets loaded (which may never happen if the sysadmin
thinks the DEFAULT_NET_SCH already made it happen)
Whoops. My bad, probably - but....
The deeper question, part 1:
There's this chunk in net/sched/Kconfig:
config DEFAULT_NET_SCH
string
default "pfifo_fast" if DEFAULT_PFIFO_FAST
default "fq" if DEFAULT_FQ
default "fq_codel" if DEFAULT_FQ_CODEL
default "fq_pie" if DEFAULT_FQ_PIE
default "sfq" if DEFAULT_SFQ
default "pfifo_fast"
endif
(And a similar chunk right above it with a similar issue)
Should those be "if (foo=y)" so =m can't be chosen? (I'll be
happy to write the patch if that's what we want)
Deeper question, part 2:
Should there be a way in the Kconfig language to ensure that
these two chunks can't accidentally get out of sync? There's other
places in the kernel where similar issues arise - a few days ago I was
chasing a CPU governor issue where it looked like it was possible
to set a default that was a module and thus possibly not actually loaded.
Attachment:
pgpuQf36l6RkX.pgp
Description: PGP signature
