Re: [PATCH net-next v7 06/13] net: mana: swap queue sets in mana_set_priv_flags

[Wei Hu <weh@linux.microsoft.com>]

Hi,

> Does this code introduce an open-coded trylock pattern?

I will keep the existing synchronization in v8. channel_changing is a
vport-admission reservation protected by vport_mutex, not an unprotected
replacement for the serialization of Ethernet reconfiguration.

RTNL serializes the Ethernet reconfiguration and reset writers. The
reservation remains set while the rebuild releases vport_mutex between
individual vport operations, so concurrent RDMA admission through
mana_cfg_vport(check=true) can reject that interval under vport_mutex.
The success and failure cleanup paths clear the reservation under the
same mutex.

Holding vport_mutex over the whole rebuild is not a drop-in replacement:
the vport configuration/unconfiguration helpers acquire it themselves.
The report does not identify a missing exclusion edge in the existing
protocol, which is also present in v6. I am not redesigning that protocol
solely on the basis of its resemblance to a trylock.

Thanks,
Wei