linux-kernel - Re: [PATCH 04/17] kcmp: In kcmp_epoll_target use fget

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200820214524.GS2074@grain>
Date:   Fri, 21 Aug 2020 00:45:24 +0300
From:   Cyrill Gorcunov <gorcunov@...il.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        criu@...nvz.org, bpf@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Oleg Nesterov <oleg@...hat.com>, Jann Horn <jann@...jh.net>,
        Kees Cook <keescook@...omium.org>,
        Daniel P. Berrangé <berrange@...hat.com>,
        Jeff Layton <jlayton@...hat.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Matthew Wilcox <willy@...ian.org>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Matthew Wilcox <matthew@....cx>,
        Trond Myklebust <trond.myklebust@....uio.no>,
        Chris Wright <chrisw@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: Re: [PATCH 04/17] kcmp: In kcmp_epoll_target use fget_task

On Mon, Aug 17, 2020 at 05:04:12PM -0500, Eric W. Biederman wrote:
> Use the helper fget_task and simplify the code.
> 
> As well as simplifying the code this removes one unnecessary increment of
> struct files_struct.  This unnecessary increment of files_struct.count can
> result in exec unnecessarily unsharing files_struct and breaking posix
> locks, and it can result in fget_light having to fallback to fget reducing
> performance.
> 
> Suggested-by: Oleg Nesterov <oleg@...hat.com>
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@...il.com>

I really like this simplification!