From mboxrd@z Thu Jan  1 00:00:00 1970
From: hch@lst.de (Christoph Hellwig)
Date: Tue, 15 May 2018 09:48:26 +0200
Subject: [PATCH 2/5] nvme: don't hold nvmf_transports_rwsem for more
 than transport lookups
In-Reply-To: <20180515074043.22843-3-jthumshirn@suse.de>
References: <20180515074043.22843-1-jthumshirn@suse.de>
 <20180515074043.22843-3-jthumshirn@suse.de>
Message-ID: <20180515074826.GA23659@lst.de>

> diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
> index 7ae732a77fe8..febf82639b40 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -957,16 +957,17 @@ nvmf_create_ctrl(struct device *dev, const char *buf, size_t count)
>  
>  	down_read(&nvmf_transports_rwsem);
>  	ops = nvmf_lookup_transport(opts);
> +	up_read(&nvmf_transports_rwsem);

And what protects us from the transport getting unregister right here
from anothet thread waiting to acquire nvmf_transports_rwsem?