netdev - how to determine if buffers are in user-space/kernel-space

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Message-ID: <20210118182636.GB15369@chelsio.com>
Date:   Mon, 18 Jan 2021 23:56:37 +0530
From:   Raju Rangoju <rajur@...lsio.com>
To:     netdev@...r.kernel.org
Cc:     hch@....de, rahul.lakkireddy@...lsio.com, rajur@...lsio.com
Subject: how to determine if buffers are in user-space/kernel-space

Hi,

We have an out-of-tree kernel module which was using
segment_eq(get_fs(), KERNEL_DS) to determine whether buffers are in
Kernel space vs User space. However, with the get_fs() and its friends
removed[1], we are out of ideas on how to determine if buffers are in
user space or kernel space. Can someone shed some light on how to
accomplish it?

Thanks in Advance,
Raju

[1]
https://patchwork.kernel.org/project/linux-fsdevel/patch/20200817073212.830069-10-hch@lst.de/