bridge: reliably pin the MAC on a bridge that lost its ports#1265
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bridge: reliably pin the MAC on a bridge that lost its ports#1265twz123 wants to merge 2 commits into
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The ensureAddr function pins the bridge's MAC address so it doesn't change as ports come and go. The pinning happens after the gateway address is set, so if a run set the address but then failed before pinning, subsequent runs never reattempted to pin the MAC, leaving behind a bridge with a floating MAC. Always pin the MAC, even if the gateway address is already present, regardless of the outcomes of previous attempts. Signed-off-by: Tom Wieczorek <twieczorek@mirantis.com>
The kernel zeroes a bridge's MAC address when its last port is removed. The ensureAddr function pins the bridge's MAC address using the address read when the bridge was looked up, which is before the veth is attached. So for an existing bridge that had previously lost all its ports, the address it tried to pin is all zeros, and pinning an all-zero address fails with EINVAL. In fact, this can happen in practice: an ADD that fails has its veth cleaned up, which, if it was the first ADD, leaves the bridge portless and hence its MAC zeroed, so the next ADD fails to pin it. Detect that case and regenerate a random MAC address the same way the kernel does. This is fine as it only happens if the bridge has no ports, so no peer can hold stale state about the old address. Signed-off-by: Tom Wieczorek <twieczorek@mirantis.com>
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The
ensureAddrfunction pins the bridge's MAC address so it doesn't change as ports come and go. The pinning happens after the gateway address is set, so if a run set the address but then failed before pinning, subsequent runs never reattempted to pin the MAC, leaving behind a bridge with a floating MAC. The kernel zeroes a bridge's MAC address when its last port is removed, andensureAddrpins the MAC using the address read when the bridge was looked up, which is before the veth is attached. So for an existing bridge that had previously lost all its ports, the address it tried to pin is all zeros, and pinning an all-zero address fails withEINVAL.In fact, this can happen in practice: an ADD that fails has its veth cleaned up, which, if it was the first ADD, leaves the bridge portless and hence its MAC zeroed, so the next ADD fails to pin it.
Always pin the MAC, even if the gateway address is already present, regardless of the outcomes of previous attempts. Detect zero MACs and regenerate a random MAC address the same way the kernel does. This is fine as it only happens if the bridge has no ports, so no peer can hold stale state about the old address.