From: "Arnd Bergmann" <arnd@arndb.de>
To: "Joe Damato" <jdamato@fastly.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, Netdev <netdev@vger.kernel.org>,
"Chuck Lever" <chuck.lever@oracle.com>,
"Jeff Layton" <jlayton@kernel.org>,
linux-api@vger.kernel.org,
"Christian Brauner" <brauner@kernel.org>,
"Eric Dumazet" <edumazet@google.com>,
"David S . Miller" <davem@davemloft.net>,
alexander.duyck@gmail.com,
"Sridhar Samudrala" <sridhar.samudrala@intel.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
weiwan@google.com, "Jonathan Corbet" <corbet@lwn.net>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Jan Kara" <jack@suse.cz>,
"Michael Ellerman" <mpe@ellerman.id.au>,
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"Steve French" <stfrench@microsoft.com>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"Jiri Slaby" <jirislaby@kernel.org>,
"Julien Panis" <jpanis@baylibre.com>,
"Andrew Waterman" <waterman@eecs.berkeley.edu>,
"Thomas Huth" <thuth@redhat.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
"open list:FILESYSTEMS (VFS and infrastructure)"
<linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH net-next v3 3/3] eventpoll: Add epoll ioctl for epoll_params
Date: Fri, 26 Jan 2024 07:16:29 +0100 [thread overview]
Message-ID: <57b62135-2159-493d-a6bb-47d5be55154a@app.fastmail.com> (raw)
In-Reply-To: <20240126023630.GA1235@fastly.com>
On Fri, Jan 26, 2024, at 03:36, Joe Damato wrote:
> On Thu, Jan 25, 2024 at 04:23:58PM -0800, Greg Kroah-Hartman wrote:
>> On Thu, Jan 25, 2024 at 04:11:28PM -0800, Joe Damato wrote:
>> > On Thu, Jan 25, 2024 at 03:21:46PM -0800, Greg Kroah-Hartman wrote:
>> > > On Thu, Jan 25, 2024 at 10:56:59PM +0000, Joe Damato wrote:
>> > > > +struct epoll_params {
>> > > > + u64 busy_poll_usecs;
>> > > > + u16 busy_poll_budget;
>> > > > +
>> > > > + /* for future fields */
>> > > > + u8 data[118];
>> > > > +} EPOLL_PACKED;
>> > >
>
> Sure, that makes sense to me. I'll remove it in the v4 alongside the other
> changes you've requested.
>
> Thanks for your time and patience reviewing my code. I greatly appreciate
> your helpful comments and feedback.
Note that you should still pad the structure to its normal
alignment. On non-x86 targets this would currently mean a
multiple of 64 bits.
I would suggest dropping the EPOLL_PACKED here entirely and
just using a fully aligned structure on all architectures, like
struct epoll_params {
__aligned_u64 busy_poll_usecs;
__u16 busy_poll_budget;
__u8 __pad[6];
};
The explicit padding can help avoid leaking stack data when
a structure is copied back from kernel to userspace, so I would
just always use it in ioctl data structures.
Arnd
next prev parent reply other threads:[~2024-01-26 6:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-25 22:56 [PATCH net-next v3 0/3] Per epoll context busy poll support Joe Damato
2024-01-25 22:56 ` [PATCH net-next v3 1/3] eventpoll: support busy poll per epoll instance Joe Damato
2024-01-25 22:56 ` [PATCH net-next v3 2/3] eventpoll: Add per-epoll busy poll packet budget Joe Damato
2024-01-25 22:56 ` [PATCH net-next v3 3/3] eventpoll: Add epoll ioctl for epoll_params Joe Damato
2024-01-25 23:20 ` Greg Kroah-Hartman
2024-01-26 0:04 ` Joe Damato
2024-01-25 23:21 ` Greg Kroah-Hartman
2024-01-26 0:11 ` Joe Damato
2024-01-26 0:23 ` Greg Kroah-Hartman
2024-01-26 2:36 ` Joe Damato
2024-01-26 6:16 ` Arnd Bergmann [this message]
2024-01-27 14:51 ` David Laight
2024-01-26 10:07 ` Christian Brauner
2024-01-26 16:52 ` Joe Damato
2024-01-25 23:22 ` Greg Kroah-Hartman
2024-01-26 0:07 ` Joe Damato
2024-01-28 11:24 ` kernel test robot
2024-01-27 16:20 ` [PATCH net-next v3 0/3] Per epoll context busy poll support Willem de Bruijn
2024-01-29 19:09 ` Joe Damato
2024-01-30 20:33 ` Willem de Bruijn
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