• Ido Schimmel's avatar
    ipv4: fib: Replay events when registering FIB notifier · c3852ef7
    Ido Schimmel authored
    Commit b90eb754 ("fib: introduce FIB notification infrastructure")
    introduced a new notification chain to notify listeners (f.e., switchdev
    drivers) about addition and deletion of routes.
    
    However, upon registration to the chain the FIB tables can already be
    populated, which means potential listeners will have an incomplete view
    of the tables.
    
    Solve that by dumping the FIB tables and replaying the events to the
    passed notification block. The dump itself is done using RCU in order
    not to starve consumers that need RTNL to make progress.
    
    The integrity of the dump is ensured by reading the FIB change sequence
    counter before and after the dump under RTNL. This allows us to avoid
    the problematic situation in which the dumping process sends a ENTRY_ADD
    notification following ENTRY_DEL generated by another process holding
    RTNL.
    
    Callers of the registration function may pass a callback that is
    executed in case the dump was inconsistent with current FIB tables.
    
    The number of retries until a consistent dump is achieved is set to a
    fixed number to prevent callers from looping for long periods of time.
    In case current limit proves to be problematic in the future, it can be
    easily converted to be configurable using a sysctl.
    Signed-off-by: default avatarIdo Schimmel <idosch@mellanox.com>
    Signed-off-by: default avatarJiri Pirko <jiri@mellanox.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    c3852ef7
ip_fib.h 10.4 KB