Messages in this thread | | | From | "Valdis Klētnieks" <> | Subject | Kconfig, DEFAULT_NETSCH, and shooting yourself in the foot.. | Date | Sat, 02 Jan 2021 15:14:47 -0500 |
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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.
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