From: "Alex Bennée" <alex.bennee@linaro.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: boost.lists@gmail.com, pavel.dovgaluk@ispras.ru, cota@braap.org,
qemu-devel@nongnu.org,
Peter Crosthwaite <crosthwaite.peter@gmail.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [RFC PATCH v1 3/9] cpus: only take BQL for sleeping threads
Date: Fri, 05 May 2017 16:28:59 +0100 [thread overview]
Message-ID: <87shkjmif8.fsf@linaro.org> (raw)
In-Reply-To: <8b648c73-ecfc-7a13-fc98-be349dcfceac@redhat.com>
Paolo Bonzini <pbonzini@redhat.com> writes:
> On 05/05/2017 12:38, Alex Bennée wrote:
>>
>> while (qemu_tcg_should_sleep(cpu)) {
>> + qemu_mutex_lock_iothread();
>> stop_tcg_kick_timer();
>> qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
>> + qemu_mutex_unlock_iothread();
>> }
>
> This is racy. You need to recheck the condition under the lock, or to
> switch from QemuCond to QemuEvent (then you still need to check the
> condition twice, the second between qemu_event_reset and qemu_event_wait).
Doh of course, being a bit too eager there ;-)
--
Alex Bennée
next prev parent reply other threads:[~2017-05-05 15:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 10:38 [Qemu-devel] [RFC PATCH v1 0/9] BQL and Replay Lock changes Alex Bennée
2017-05-05 10:38 ` [RFC PATCH v1 1/9] target/arm/arm-powertctl: drop BQL assertions Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] " Alex Bennée
2017-05-05 10:38 ` [RFC PATCH v1 2/9] cpus: push BQL lock to qemu_*_wait_io_event Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] " Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 3/9] cpus: only take BQL for sleeping threads Alex Bennée
2017-05-05 15:15 ` Paolo Bonzini
2017-05-05 15:28 ` Alex Bennée [this message]
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 4/9] replay/replay-internal.c: track holding of replay_lock Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 5/9] replay: make locking visible outside replay code Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 6/9] replay: push replay_mutex_lock up the call tree Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 7/9] scripts/qemu-gdb: add simple tcg lock status helper Alex Bennée
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 8/9] util/qemu-thread-*: add qemu_lock, locked and unlock trace events Alex Bennée
2017-05-05 15:17 ` Paolo Bonzini
2017-05-05 15:59 ` Alex Bennée
2017-05-06 8:19 ` Paolo Bonzini
2017-05-08 17:52 ` Stefan Hajnoczi
2017-05-09 13:50 ` Alex Bennée
2017-05-09 13:55 ` Paolo Bonzini
2017-05-05 10:38 ` [Qemu-devel] [RFC PATCH v1 9/9] scripts/analyse-locks-simpletrace.py: script to analyse lock times Alex Bennée
2017-05-05 15:38 ` [Qemu-devel] [RFC PATCH v1 0/9] BQL and Replay Lock changes no-reply
2017-05-10 13:51 ` Pavel Dovgalyuk
2017-05-10 15:24 ` Alex Bennée
2017-05-11 11:23 ` Pavel Dovgalyuk
2017-06-05 10:52 ` Pavel Dovgalyuk
2017-06-06 9:34 ` Alex Bennée
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