From: Al Viro <viro@zeniv.linux.org.uk>
To: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH RFC] uaccess: user_access_begin_after_access_ok()
Date: Thu, 4 Jun 2020 15:59:24 +0100 [thread overview]
Message-ID: <20200604145924.GF23230@ZenIV.linux.org.uk> (raw)
In-Reply-To: <ec086f7b-be01-5ffd-6fc3-f865d26b0daf@redhat.com>
On Thu, Jun 04, 2020 at 02:10:27PM +0800, Jason Wang wrote:
> > > get_user(flags, desc->flags)
> > > smp_rmb()
> > > if (flags & VALID)
> > > copy_from_user(&adesc, desc, sizeof adesc);
> > >
> > > this would be a good candidate I think.
> > Perhaps, once we get stac/clac out of raw_copy_from_user() (coming cycle,
> > probably). BTW, how large is the structure and how is it aligned?
>
>
> Each descriptor is 16 bytes, and 16 bytes aligned.
Won't it be cheaper to grap the entire thing unconditionally? And what does
that rmb order, while we are at it - won't all coherency work in terms of
entire cachelines anyway?
Confused...
next prev parent reply other threads:[~2020-06-04 14:59 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 8:45 [PATCH RFC] uaccess: user_access_begin_after_access_ok() Michael S. Tsirkin
2020-06-02 10:15 ` Jason Wang
2020-06-02 16:33 ` Al Viro
2020-06-02 17:18 ` Linus Torvalds
2020-06-02 17:44 ` Al Viro
2020-06-02 17:46 ` Al Viro
2020-06-02 20:32 ` Michael S. Tsirkin
2020-06-02 20:41 ` David Laight
2020-06-02 21:58 ` Al Viro
2020-06-03 8:08 ` David Laight
2020-06-02 20:43 ` Linus Torvalds
2020-06-03 6:01 ` Michael S. Tsirkin
[not found] ` <CAHk-=wi3=QuD30fRq8fYYTj9WmkgeZ0VR_Sh3DQHU+nmwj-jMg@mail.gmail.com>
2020-06-03 16:59 ` Linus Torvalds
2020-06-02 16:30 ` Al Viro
2020-06-02 20:42 ` Michael S. Tsirkin
2020-06-02 22:10 ` Al Viro
2020-06-03 5:17 ` Michael S. Tsirkin
2020-06-03 1:48 ` Al Viro
2020-06-03 3:57 ` Jason Wang
2020-06-03 4:18 ` Al Viro
2020-06-03 5:18 ` Jason Wang
2020-06-03 5:46 ` Michael S. Tsirkin
2020-06-03 6:23 ` Jason Wang
2020-06-03 6:30 ` Michael S. Tsirkin
2020-06-03 6:36 ` Jason Wang
2020-06-04 16:49 ` Michael S. Tsirkin
2020-06-05 10:03 ` Jason Wang
2020-06-06 20:08 ` Michael S. Tsirkin
2020-06-03 6:25 ` Michael S. Tsirkin
2020-06-03 5:29 ` Michael S. Tsirkin
2020-06-03 16:52 ` Al Viro
2020-06-04 6:10 ` Jason Wang
2020-06-04 14:59 ` Al Viro [this message]
2020-06-04 16:46 ` Michael S. Tsirkin
2020-06-04 10:10 ` Michael S. Tsirkin
2020-06-04 15:03 ` Al Viro
2020-06-04 16:47 ` Michael S. Tsirkin
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