From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christian Brauner <christian@brauner.io>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Kees Cook <keescook@chromium.org>,
Joel Fernandes <joel@joelfernandes.org>,
Thomas Gleixner <tglx@linutronix.de>, Tejun Heo <tj@kernel.org>,
David Howells <dhowells@redhat.com>, Jann Horn <jannh@google.com>,
Andrew Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Aleksa Sarai <cyphar@cyphar.com>,
Android Kernel Team <kernel-team@android.com>
Subject: Re: [PATCH v2 1/2] pidfd: add P_PIDFD to waitid()
Date: Sat, 27 Jul 2019 17:49:32 +0100 [thread overview]
Message-ID: <20190727164932.GR1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CAHk-=whrh5+aHmgqP9YhZ-yzCtUWT8fPi08ZSJdxusx7aHXOQQ@mail.gmail.com>
On Sat, Jul 27, 2019 at 09:28:40AM -0700, Linus Torvalds wrote:
> is the stupid and straightforward thing, but if you want to be
> *clever* you can actually avoid getting a reference to the 'struct
> file *" entirely, and do the fd->pid lookup under rcu_read_lock()
> instead. It's slightly more complex, but it avoids the fdget/fdput
> reference count games entirely.
Yecchhh... Please, don't do the last part - at least not unless
we really see that in profiles.
next prev parent reply other threads:[~2019-07-27 16:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-27 8:51 [PATCH v2 0/2] pidfd: waiting on processes through pidfds Christian Brauner
2019-07-27 8:52 ` [PATCH v2 1/2] pidfd: add P_PIDFD to waitid() Christian Brauner
2019-07-27 16:28 ` Linus Torvalds
2019-07-27 16:41 ` Linus Torvalds
2019-07-27 19:42 ` Christian Brauner
2019-07-27 16:49 ` Al Viro [this message]
2019-07-27 19:46 ` Christian Brauner
2019-07-27 19:45 ` Christian Brauner
2019-07-27 8:52 ` [PATCH v2 2/2] pidfd: add pidfd_wait tests Christian Brauner
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