linux-kernel - Re: [PATCH v5 for-next 0/3] IB/core: Obtaining subnet

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Date:   Mon, 21 Jun 2021 20:52:57 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Anand Khoje <anand.a.khoje@...cle.com>
Cc:     linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        dledford@...hat.com, haakon.bugge@...cle.com, leon@...nel.org
Subject: Re: [PATCH v5 for-next 0/3] IB/core: Obtaining subnet_prefix from
 cache in

On Wed, Jun 16, 2021 at 09:15:06PM +0530, Anand Khoje wrote:
> This v5 patch series is used to read the port_attribute subnet_prefix
> from a valid cache entry instead of having to call
> device->ops.query_gid() in Infiniband link-layer devices. This requires
> addition of a flag used to check that the cache entry is initialized and
> that a valid value is being read.
> 
> 1. Removed the port validity check from ib_get_cached_subnet_prefix.
> This check was not useful as the port_num is always valid.
> 
> 2. Shuffled locks pkey_lost_lock and netdev_lock in struct ib_port_data.
> This was done as output of pahole showed two 4-byte holes in the
> structure ib_port_data after pkey_list_lock and netdev_lock. Moving
> netdev_lock shaved off 8 bytes from the structure.
> 
> 3. Added a flag to struct ib_port_data. This is used to validate the
> status of cached subnet_prefix. This valid cache entry of subnet_prefix
> is used in function __ib_query_port().
> This allows the utilization of the cache entry and hence avoids a call
> into device->ops.query_gid(). We also ensure that in the event of a
> cache update, the value for subnet_prefix gets read from the newly updated
> GID cache and not via ib_query_port(), so that we do not end up reading a
> stale cache value.
> 
> Anand Khoje (3):
>   IB/core: Removed port validity check from ib_get_cached_subnet_prefix
>   IB/core: Shuffle locks in ib_port_data to save memory

I took these two, thanks

Jason