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Date:   Wed, 16 Jun 2021 10:30:16 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     Anand Khoje <anand.a.khoje@oracle.com>
Cc:     linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        dledford@redhat.com, jgg@ziepe.ca, haakon.bugge@oracle.com
Subject: Re: [PATCH v4 for-next 3/3] IB/core: Obtain subnet_prefix from cache
 in IB devices
Message-ID: <YMmoiD5mXm4/OWj3@unreal>
References: <20210616065213.987-1-anand.a.khoje@oracle.com>
 <20210616065213.987-4-anand.a.khoje@oracle.com>
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On Wed, Jun 16, 2021 at 12:22:13PM +0530, Anand Khoje wrote:
> ib_query_port() calls device->ops.query_port() to get the port
> attributes. The method of querying is device driver specific.
> The same function calls device->ops.query_gid() to get the GID and
> extract the subnet_prefix (gid_prefix).
> 
> The GID and subnet_prefix are stored in a cache. But they do not get
> read from the cache if the device is an Infiniband device. The
> following change takes advantage of the cached subnet_prefix.
> Testing with RDBMS has shown a significant improvement in performance
> with this change.
> 
> The function ib_cache_is_initialised() is introduced because
> ib_query_port() gets called early in the stage when the cache is not
> built while reading port immutable property.
> 
> In that case, the default GID still gets read from HCA for IB link-
> layer devices.
> 
> In the situation of an event causing cache update, the subnet_prefix
> will get retrieved from newly updated GID cache in ib_cache_update(),
> so that we do not end up reading a stale value from cache via
> ib_query_port().
> 
> Fixes: fad61ad ("IB/core: Add subnet prefix to port info")
> Suggested-by: Leon Romanovsky <leonro@nvidia.com>
> Suggested-by: Aru Kolappan <aru.kolappan@oracle.com>
> Signed-off-by: Anand Khoje <anand.a.khoje@oracle.com>
> Signed-off-by: Haakon Bugge <haakon.bugge@oracle.com>
> ---

<...>

> @@ -1523,13 +1526,21 @@ static int config_non_roce_gid_cache(struct ib_device *device,
>  	device->port_data[port].cache.lmc = tprops->lmc;
>  	device->port_data[port].cache.port_state = tprops->state;
>  
> -	device->port_data[port].cache.subnet_prefix = tprops->subnet_prefix;
> +	ret = rdma_query_gid(device, port, 0, &gid);
> +	if (ret) {
> +		write_unlock_irq(&device->cache.lock);

And this patch can't compile. It should be cache_lock and not cache.lock.

Thanks