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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 29 Apr 2020 09:42:04 +0200
Message-ID: <CAK8P3a2s3SLw7qehipMCP2m4TG+S089nBiqFfY3c7M2qjVTHWw@mail.gmail.com>
Subject: Re: [RFC PATCH] powerpc/spufs: fix copy_to_user while atomic
To:     Jeremy Kerr <jk@ozlabs.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Wed, Apr 29, 2020 at 8:33 AM Jeremy Kerr <jk@ozlabs.org> wrote:
>
> Hi Christoph,
>
> > And another one that should go on top of this one to address Al's other
> > compaint:
>
> Yeah, I was pondering that one. The access_ok() is kinda redundant, but
> it does avoid forcing a SPU context save on those errors.
>
> However, it's not like we really need to optimise for the case of
> invalid addresses from userspace. So, I'll include this change in the
> submission to Michael's tree. Arnd - let me know if you have any
> objections.

Sounds good. A lot of the access_ok() checks in the kernel are redundant
or wrong, I think it makes a lot of sense to remove these.

       Arnd