From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33381) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YSNHz-00024n-Mo for qemu-devel@nongnu.org; Mon, 02 Mar 2015 05:09:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YSNHy-0007ru-Qk for qemu-devel@nongnu.org; Mon, 02 Mar 2015 05:09:27 -0500 Received: from mail-wi0-x22a.google.com ([2a00:1450:400c:c05::22a]:39516) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YSNHy-0007rm-Ko for qemu-devel@nongnu.org; Mon, 02 Mar 2015 05:09:26 -0500 Received: by widex7 with SMTP id ex7so13505087wid.4 for ; Mon, 02 Mar 2015 02:09:26 -0800 (PST) Received: from localhost.localdomain (net-37-116-207-136.cust.vodafonedsl.it. [37.116.207.136]) by mx.google.com with ESMTPSA id g10sm15364685wic.7.2015.03.02.02.09.24 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Mar 2015 02:09:25 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Mon, 2 Mar 2015 11:08:54 +0100 Message-Id: <1425290934-60872-16-git-send-email-pbonzini@redhat.com> In-Reply-To: <1425290934-60872-1-git-send-email-pbonzini@redhat.com> References: <1425290934-60872-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 15/15] cpus: be more paranoid in avoiding deadlocks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org For good measure, ensure that the following sequence: thread 1 calls qemu_mutex_lock_iothread thread 2 calls qemu_mutex_lock_iothread VCPU thread are created VCPU thread enters execution loop results in the VCPU threads letting the other two threads run and obeying iothread_requesting_mutex even if the VCPUs are not halted. To do this, check iothread_requesting_mutex before execution starts. Tested-by: Leon Alrae Signed-off-by: Paolo Bonzini --- cpus.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/cpus.c b/cpus.c index 83c078e..0fac143 100644 --- a/cpus.c +++ b/cpus.c @@ -1025,6 +1025,9 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) } } + /* process any pending work */ + exit_request = 1; + while (1) { tcg_exec_all(); @@ -1115,10 +1118,11 @@ bool qemu_in_vcpu_thread(void) void qemu_mutex_lock_iothread(void) { + atomic_inc(&iothread_requesting_mutex); if (!tcg_enabled() || !first_cpu) { qemu_mutex_lock(&qemu_global_mutex); + atomic_dec(&iothread_requesting_mutex); } else { - atomic_inc(&iothread_requesting_mutex); if (qemu_mutex_trylock(&qemu_global_mutex)) { qemu_cpu_kick_thread(first_cpu); qemu_mutex_lock(&qemu_global_mutex); -- 2.3.0