From: Jan Glauber <jglauber@marvell.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>,
lizhengui <lizhengui@huawei.com>,
dann frazier <dann.frazier@canonical.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Bug 1805256 <1805256@bugs.launchpad.net>,
QEMU Developers - ARM <qemu-arm@nongnu.org>
Subject: Re: [Qemu-devel] qemu_futex_wait() lockups in ARM64: 2 possible issues
Date: Wed, 2 Oct 2019 11:05:59 +0000 [thread overview]
Message-ID: <20191002110550.GA3482@hc> (raw)
In-Reply-To: <ed5c4522-9250-e403-c55d-d3dbcda82540@redhat.com>
On Wed, Oct 02, 2019 at 11:45:19AM +0200, Paolo Bonzini wrote:
> On 02/10/19 11:23, Jan Glauber wrote:
> > I've tried to verify me theory with this patch and didn't run into the
> > issue for ~500 iterations (usually I would trigger the issue ~20 iterations).
>
> Awesome! That would be a compiler bug though, as atomic_add and atomic_sub
> are defined as sequentially consistent:
>
> #define atomic_add(ptr, n) ((void) __atomic_fetch_add(ptr, n, __ATOMIC_SEQ_CST))
> #define atomic_sub(ptr, n) ((void) __atomic_fetch_sub(ptr, n, __ATOMIC_SEQ_CST))
Compiler bug sounds kind of unlikely...
> What compiler are you using and what distro? Can you compile util/aio-posix.c
> with "-fdump-rtl-all -fdump-tree-all", zip the boatload of debugging files and
> send them my way?
This is on Ubuntu 18.04.3,
gcc version 7.4.0 (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1)
I've uploaded the debug files to:
https://bugs.launchpad.net/qemu/+bug/1805256/+attachment/5293619/+files/aio-posix.tar.xz
Thanks,
Jan
> Thanks,
>
> Paolo
next prev parent reply other threads:[~2019-10-02 12:27 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 2:15 [Qemu-arm] qemu_futex_wait() lockups in ARM64: 2 possible issues Rafael David Tinoco
2019-09-11 7:05 ` Rafael David Tinoco
2019-09-11 13:17 ` Paolo Bonzini
2019-09-11 14:48 ` [Qemu-devel] " Rafael David Tinoco
2019-09-11 19:09 ` [Qemu-arm] " Rafael David Tinoco
2019-09-24 20:25 ` [Qemu-devel] " dann frazier
2019-10-02 9:23 ` Jan Glauber
2019-10-02 9:45 ` Paolo Bonzini
2019-10-02 11:05 ` Jan Glauber [this message]
2019-10-02 13:20 ` memory barriers and ATOMIC_SEQ_CST on aarch64 (was Re: [Qemu-devel] qemu_futex_wait() lockups in ARM64: 2 possible issues) Paolo Bonzini
2019-10-02 14:58 ` Torvald Riegel
2019-10-02 16:30 ` Paolo Bonzini
2019-10-07 11:06 ` [Qemu-devel] qemu_futex_wait() lockups in ARM64: 2 possible issues Paolo Bonzini
2019-10-07 14:36 ` Jan Glauber
2019-10-07 14:44 ` dann frazier
2019-10-07 14:58 ` Paolo Bonzini
2019-10-09 8:02 ` Jan Glauber
2019-10-09 9:15 ` Paolo Bonzini
2019-10-11 6:05 ` Jan Glauber
2019-10-11 8:18 ` Paolo Bonzini
2019-10-11 8:30 ` Jan Glauber
2019-10-11 17:50 ` dann frazier
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