From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51132) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eC24Q-0002WZ-KK for qemu-devel@nongnu.org; Tue, 07 Nov 2017 06:29:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eC24N-0004RQ-7I for qemu-devel@nongnu.org; Tue, 07 Nov 2017 06:29:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44818) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eC24N-0004Qv-15 for qemu-devel@nongnu.org; Tue, 07 Nov 2017 06:29:27 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2336D5D5E6 for ; Tue, 7 Nov 2017 11:29:26 +0000 (UTC) References: <20171106190233.1175-1-stefanha@redhat.com> From: Paolo Bonzini Message-ID: <1164825c-8f4a-ec21-0a29-ae0ff42bdb1d@redhat.com> Date: Tue, 7 Nov 2017 12:29:18 +0100 MIME-Version: 1.0 In-Reply-To: <20171106190233.1175-1-stefanha@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.11] tests-aio-multithread: fix /aio/multi/schedule race condition List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , qemu-devel@nongnu.org On 06/11/2017 20:02, Stefan Hajnoczi wrote: > test_multi_co_schedule_entry() set to_schedule[id] in the final loop > iteration before terminating the coroutine. There is a race condition > where the main thread attempts to enter the terminating or terminated > coroutine when signalling coroutines to stop: > > atomic_mb_set(&now_stopping, true); > for (i = 0; i < NUM_CONTEXTS; i++) { > ctx_run(i, finish_cb, NULL); <--- enters dead coroutine! > to_schedule[i] = NULL; > } > > Make sure only to set to_schedule[id] if this coroutine really needs to > be scheduled! > > Reported-by: "R.Nageswara Sastry" > Signed-off-by: Stefan Hajnoczi > --- > This patch is appropriate for the QEMU 2.11 release to eliminate > spurious test failures. > > tests/test-aio-multithread.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/tests/test-aio-multithread.c b/tests/test-aio-multithread.c > index 549d784915..d396185972 100644 > --- a/tests/test-aio-multithread.c > +++ b/tests/test-aio-multithread.c > @@ -144,17 +144,16 @@ static void finish_cb(void *opaque) > static coroutine_fn void test_multi_co_schedule_entry(void *opaque) > { > g_assert(to_schedule[id] == NULL); > - atomic_mb_set(&to_schedule[id], qemu_coroutine_self()); > > while (!atomic_mb_read(&now_stopping)) { > int n; > > n = g_test_rand_int_range(0, NUM_CONTEXTS); > schedule_next(n); > + > + atomic_mb_set(&to_schedule[id], qemu_coroutine_self()); > qemu_coroutine_yield(); > - > g_assert(to_schedule[id] == NULL); > - atomic_mb_set(&to_schedule[id], qemu_coroutine_self()); > } > } > > Reviewed-by: Paolo Bonzini Thanks, Paolo