Install system route to kernel?

[xdxu]

frr/zebra/zebra_rib.c

Line 1000 in a89a782

if (!CHECK_FLAG(new->status, ROUTE_ENTRY_INSTALLED) ||

Before the change the condition check looks like:

if (not system route && not installed)
    /* install to kernel */

Not sure why it is changed to

if (not installed || system route)
    /* install to kernel */

which does not sound right to me.

[mjstapp]

It looks like that code has been in place for three years or so, so this isn't a recent change? I'm willing to believe Donald's comment, that there are race conditions that make this possible. Is there some specific problem you are experiencing?

[xdxu]

No I didn't run into any issue but I'm curious by we updated the checking conditions, as I thought FRR is not supposed to install any system route into the kernel even if it is selected.
The comment for race condition had been there before last change so I guess the most recent change has nothing to do with race condition.

[donaldsharp]

it doesn't install any system route. We changed this path to make all calls to install routes go to the dataplane and the dataplane will return success here.

That way every call success / failure folllows the same code path and we do not have to worry about fixing the special case code path when another change comes down the pike