Re: [PATCH net] macvlan: fix allmulti reference counting in passthru mode

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Dave Miller <davem@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>:

On Mon, 26 Oct 2026 19:46:35 -0700 you wrote:
> Enabling allmulticast on a down passthru macvlan, bringing it up,
> then toggling allmulticast off and on can underflow the lower device's
> allmulti reference count.
> 
> macvlan_change_rx_flags() only propagates IFF_ALLMULTI changes while
> the macvlan is up. However, the passthru path in macvlan_open() skips
> taking an allmulti reference when IFF_ALLMULTI is already set.
> Clearing allmulticast after opening the device therefore decrements
> a reference that was never taken. With no other allmulti users, the
> unsigned counter wraps from zero to UINT_MAX. The next increment
> fails with -EOVERFLOW and reports "allmulti touches roof".
> 
> [...]

Here is the summary with links:
  - [net] macvlan: fix allmulti reference counting in passthru mode
    https://git.kernel.org/netdev/net/c/d8a4f4c59da5

You are awesome, thank you!
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