On Thu, Apr 09, 2015 at 11:21:10AM +0200, Paolo Bonzini wrote:
> There are two problems with memory barriers in async.c. The fix is
> to use atomic_xchg in order to achieve sequential consistency between
> the scheduling of a bottom half and the corresponding execution.
>
> First, if bh->schedule
There are two problems with memory barriers in async.c. The fix is
to use atomic_xchg in order to achieve sequential consistency between
the scheduling of a bottom half and the corresponding execution.
First, if bh->scheduled is already 1 in qemu_bh_schedule, QEMU does
not execute a memory barrie
On Tue, Apr 7, 2015 at 4:16 PM, Paolo Bonzini wrote:
> There are two problems with memory barriers in async.c. The fix is
> to use atomic_xchg in order to achieve sequential consistency between
> the scheduling of a bottom half and the corresponding execution.
>
> First, if bh->scheduled is alrea
Paolo,
I've applied your patch in place of my prototype patch and, as expected, it's
working fine. Thanks!
-Original Message-
From: Paolo Bonzini [mailto:pbonz...@redhat.com]
Sent: Tuesday, April 07, 2015 11:16 AM
To: qemu-devel@nongnu.org
Cc: ler...@redhat.com; Leveille, Paul; stefa...
On 04/08/15 12:15, Richard W.M. Jones wrote:
> On Tue, Apr 07, 2015 at 05:16:19PM +0200, Paolo Bonzini wrote:
>> This bug is, most likely, also the cause of failures in the libguestfs
>> testsuite on AArch64.
>
> I'm afraid I have to agree with Laszlo, that this patch unfortunately
> does not cure
On Tue, Apr 07, 2015 at 05:16:19PM +0200, Paolo Bonzini wrote:
> This bug is, most likely, also the cause of failures in the libguestfs
> testsuite on AArch64.
I'm afraid I have to agree with Laszlo, that this patch unfortunately
does not cure the aarch64 race.
The test case I'm using is:
http://
On 04/07/15 20:20, Leveille, Paul wrote:
> Paolo,
>
> I've applied your patch in place of my prototype patch and, as expected, it's
> working fine. Thanks!
I also tested the patch (on top of 5a24f20a72), and on aarch64 it
doesn't fix the hang.
If there's interest, I can write up the reproducer
There are two problems with memory barriers in async.c. The fix is
to use atomic_xchg in order to achieve sequential consistency between
the scheduling of a bottom half and the corresponding execution.
First, if bh->scheduled is already 1 in qemu_bh_schedule, QEMU does
not execute a memory barrie
