Understanding Linux Network Internals

Deleting a Bridge

Before a bridge device can be removed, it must be shut down. If it hasn't been shut down, br_del_bridge returns -EBUSY and refuses to remove the device. To remove it, br_del_bridge invokes del_br, which does most of the work, as follows:

• Removes all its bridge ports. For each bridge port, it also removes the associated links (which appear as directories) in /sys. See the section "Deleting a Bridge Port."

• For each port, removes all the associated entries in the forwarding database with br_fdb_delete_by_port, stops all the port's timers, and decrements the promiscuity counter. (The promiscuity counter is described in the upcoming section, "Adding Ports to a Bridge.")

• Stops the garbage collection timer br->gc_timer.

• Removes the bridge device directory in the /sys/class/net directory with br_sysfs_delbr.

• Unregisters the device with unregister_netdevice. This function is described in Chapter 8.