From: Peter Zijlstra <peterz@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Jann Horn <jannh@google.com>,
Greg KH <gregkh@linuxfoundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
raven@themaw.net, linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
linux-block@vger.kernel.org, keyrings@vger.kernel.org,
linux-security-module <linux-security-module@vger.kernel.org>,
kernel list <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH 1/7] General notification queue with user mmap()'able ring buffer
Date: Fri, 31 May 2019 13:14:45 +0200 [thread overview]
Message-ID: <20190531111445.GO2677@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <16193.1559163763@warthog.procyon.org.uk>
On Wed, May 29, 2019 at 10:02:43PM +0100, David Howells wrote:
> Jann Horn <jannh@google.com> wrote:
>
> > Does this mean that refcount_read() isn't sufficient for what you want
> > to do with tracing (because for some reason you actually need to know
> > the values atomically at the time of increment/decrement)?
>
> Correct. There's a gap and if an interrupt or something occurs, it's
> sufficiently big for the refcount trace to go weird.
>
> I've seen it in afs/rxrpc where the incoming network packets that are part of
> the rxrpc call flow disrupt the refcounts noted in trace lines.
Can you re-iterate the exact problem? I konw we talked about this in the
past, but I seem to have misplaced those memories :/
FWIW I agree that kref is useless fluff, but I've long ago given up on
that fight.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Jann Horn <jannh@google.com>,
Greg KH <gregkh@linuxfoundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
raven@themaw.net, linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
linux-block@vger.kernel.org, keyrings@vger.kernel.org,
linux-security-module <linux-security-module@vger.kernel.org>,
kernel list <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH 1/7] General notification queue with user mmap()'able ring buffer
Date: Fri, 31 May 2019 11:14:45 +0000 [thread overview]
Message-ID: <20190531111445.GO2677@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <16193.1559163763@warthog.procyon.org.uk>
On Wed, May 29, 2019 at 10:02:43PM +0100, David Howells wrote:
> Jann Horn <jannh@google.com> wrote:
>
> > Does this mean that refcount_read() isn't sufficient for what you want
> > to do with tracing (because for some reason you actually need to know
> > the values atomically at the time of increment/decrement)?
>
> Correct. There's a gap and if an interrupt or something occurs, it's
> sufficiently big for the refcount trace to go weird.
>
> I've seen it in afs/rxrpc where the incoming network packets that are part of
> the rxrpc call flow disrupt the refcounts noted in trace lines.
Can you re-iterate the exact problem? I konw we talked about this in the
past, but I seem to have misplaced those memories :/
FWIW I agree that kref is useless fluff, but I've long ago given up on
that fight.
next prev parent reply other threads:[~2019-05-31 11:15 UTC|newest]
Thread overview: 131+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-28 16:01 [RFC][PATCH 0/7] Mount, FS, Block and Keyrings notifications David Howells
2019-05-28 16:01 ` David Howells
2019-05-28 16:01 ` [PATCH 1/7] General notification queue with user mmap()'able ring buffer David Howells
2019-05-28 16:01 ` David Howells
2019-05-28 16:26 ` Greg KH
2019-05-28 16:26 ` Greg KH
2019-05-28 17:30 ` David Howells
2019-05-28 17:30 ` David Howells
2019-05-28 23:12 ` Greg KH
2019-05-28 23:12 ` Greg KH
2019-05-29 16:06 ` David Howells
2019-05-29 16:06 ` David Howells
2019-05-29 17:46 ` Jann Horn
2019-05-29 17:46 ` Jann Horn
2019-05-29 21:02 ` David Howells
2019-05-29 21:02 ` David Howells
2019-05-31 11:14 ` Peter Zijlstra [this message]
2019-05-31 11:14 ` Peter Zijlstra
2019-05-31 12:02 ` David Howells
2019-05-31 12:02 ` David Howells
2019-05-31 13:26 ` Peter Zijlstra
2019-05-31 13:26 ` Peter Zijlstra
2019-05-31 14:20 ` David Howells
2019-05-31 14:20 ` David Howells
2019-05-31 16:44 ` Peter Zijlstra
2019-05-31 16:44 ` Peter Zijlstra
2019-05-31 17:12 ` David Howells
2019-05-31 17:12 ` David Howells
2019-06-17 16:24 ` Peter Zijlstra
2019-06-17 16:24 ` Peter Zijlstra
2019-05-29 23:09 ` Greg KH
2019-05-29 23:09 ` Greg KH
2019-05-29 23:11 ` Greg KH
2019-05-29 23:11 ` Greg KH
2019-05-30 9:50 ` Andrea Parri
2019-05-30 9:50 ` Andrea Parri
2019-05-31 8:35 ` Peter Zijlstra
2019-05-31 8:35 ` Peter Zijlstra
2019-05-31 8:47 ` Peter Zijlstra
2019-05-31 8:47 ` Peter Zijlstra
2019-05-31 12:42 ` David Howells
2019-05-31 12:42 ` David Howells
2019-05-31 14:55 ` David Howells
2019-05-31 14:55 ` David Howells
2019-05-28 19:14 ` Jann Horn
2019-05-28 19:14 ` Jann Horn
2019-05-28 22:28 ` David Howells
2019-05-28 22:28 ` David Howells
2019-05-28 23:16 ` Jann Horn
2019-05-28 23:16 ` Jann Horn
2019-05-28 16:02 ` [PATCH 2/7] keys: Add a notification facility David Howells
2019-05-28 16:02 ` David Howells
2019-05-28 16:02 ` [PATCH 3/7] vfs: Add a mount-notification facility David Howells
2019-05-28 16:02 ` David Howells
2019-05-28 20:06 ` Jann Horn
2019-05-28 20:06 ` Jann Horn
2019-05-28 23:04 ` David Howells
2019-05-28 23:04 ` David Howells
2019-05-28 23:23 ` Jann Horn
2019-05-28 23:23 ` Jann Horn
2019-05-29 11:16 ` David Howells
2019-05-29 11:16 ` David Howells
2019-05-28 23:08 ` David Howells
2019-05-28 23:08 ` David Howells
2019-05-29 10:55 ` David Howells
2019-05-29 10:55 ` David Howells
2019-05-29 11:00 ` David Howells
2019-05-29 11:00 ` David Howells
2019-05-29 15:53 ` Casey Schaufler
2019-05-29 15:53 ` Casey Schaufler
2019-05-29 16:12 ` Jann Horn
2019-05-29 16:12 ` Jann Horn
2019-05-29 17:04 ` Casey Schaufler
2019-05-29 17:04 ` Casey Schaufler
2019-06-03 16:30 ` David Howells
2019-06-03 16:30 ` David Howells
2019-05-29 17:13 ` Andy Lutomirski
2019-05-29 17:13 ` Andy Lutomirski
2019-05-29 17:46 ` Casey Schaufler
2019-05-29 17:46 ` Casey Schaufler
2019-05-29 18:11 ` Jann Horn
2019-05-29 18:11 ` Jann Horn
2019-05-29 19:28 ` Casey Schaufler
2019-05-29 19:28 ` Casey Schaufler
2019-05-29 19:47 ` Jann Horn
2019-05-29 19:47 ` Jann Horn
2019-05-29 20:50 ` Casey Schaufler
2019-05-29 20:50 ` Casey Schaufler
2019-05-29 23:12 ` Andy Lutomirski
2019-05-29 23:12 ` Andy Lutomirski
2019-05-29 23:56 ` Casey Schaufler
2019-05-29 23:56 ` Casey Schaufler
2019-05-28 16:02 ` [PATCH 4/7] vfs: Add superblock notifications David Howells
2019-05-28 16:02 ` David Howells
2019-05-28 20:27 ` Jann Horn
2019-05-28 20:27 ` Jann Horn
2019-05-29 12:58 ` David Howells
2019-05-29 12:58 ` David Howells
2019-05-29 14:16 ` Jann Horn
2019-05-29 14:16 ` Jann Horn
2019-05-28 16:02 ` [PATCH 5/7] fsinfo: Export superblock notification counter David Howells
2019-05-28 16:02 ` David Howells
2019-05-28 16:02 ` [PATCH 6/7] block: Add block layer notifications David Howells
2019-05-28 16:02 ` David Howells
2019-05-28 20:37 ` Jann Horn
2019-05-28 20:37 ` Jann Horn
2019-05-28 16:02 ` [PATCH 7/7] Add sample notification program David Howells
2019-05-28 16:02 ` David Howells
2019-05-28 23:58 ` [RFC][PATCH 0/7] Mount, FS, Block and Keyrings notifications Greg KH
2019-05-28 23:58 ` Greg KH
2019-05-29 6:33 ` Amir Goldstein
2019-05-29 6:33 ` Amir Goldstein
2019-05-29 6:33 ` Amir Goldstein
2019-05-29 14:25 ` Jan Kara
2019-05-29 14:25 ` Jan Kara
2019-05-29 15:10 ` Greg KH
2019-05-29 15:10 ` Greg KH
2019-05-29 15:53 ` Amir Goldstein
2019-05-29 15:53 ` Amir Goldstein
2019-05-30 11:00 ` Jan Kara
2019-05-30 11:00 ` Jan Kara
2019-06-04 12:33 ` David Howells
2019-06-04 12:33 ` David Howells
2019-05-29 6:45 ` David Howells
2019-05-29 6:45 ` David Howells
2019-05-29 7:40 ` Amir Goldstein
2019-05-29 7:40 ` Amir Goldstein
2019-05-29 9:09 ` David Howells
2019-05-29 9:09 ` David Howells
2019-05-29 15:41 ` Casey Schaufler
2019-05-29 15:41 ` Casey Schaufler
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190531111445.GO2677@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=dhowells@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=jannh@google.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=keyrings@vger.kernel.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=raven@themaw.net \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.