From: Paolo Bonzini <pbonzini@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-block@nongnu.org
Cc: kwolf@redhat.com, Fam Zheng <fam@euphon.net>,
qemu-devel@nongnu.org, mreitz@redhat.com, rvkagan@yandex-team.ru,
Stefan Hajnoczi <stefanha@redhat.com>,
den@openvz.org
Subject: Re: [PATCH v3 06/33] util/async: aio_co_schedule(): support reschedule in same ctx
Date: Thu, 13 May 2021 23:04:37 +0200 [thread overview]
Message-ID: <ef518e01-4f08-5fe7-b226-e70ab3102ca4@redhat.com> (raw)
In-Reply-To: <19ff6e67-e548-14df-ac7e-8b0a3bf7a798@virtuozzo.com>
On 12/05/21 09:15, Vladimir Sementsov-Ogievskiy wrote:
>>>
>>
>> I don't understand. Why doesn't aio_co_enter go through the ctx !=
>> qemu_get_current_aio_context() branch and just do aio_co_schedule?
>> That was at least the idea behind aio_co_wake and aio_co_enter.
>>
>
> Because ctx is exactly qemu_get_current_aio_context(), as we are not in
> iothread but in nbd connection thread. So,
> qemu_get_current_aio_context() returns qemu_aio_context.
So the problem is that threads other than the main thread and
the I/O thread should not return qemu_aio_context. The vCPU thread
may need to return it when running with BQL taken, though.
Something like this (untested):
diff --git a/include/block/aio.h b/include/block/aio.h
index 5f342267d5..10fcae1515 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -691,10 +691,13 @@ void aio_co_enter(AioContext *ctx, struct Coroutine *co);
* Return the AioContext whose event loop runs in the current thread.
*
* If called from an IOThread this will be the IOThread's AioContext. If
- * called from another thread it will be the main loop AioContext.
+ * called from the main thread or with the "big QEMU lock" taken it
+ * will be the main loop AioContext.
*/
AioContext *qemu_get_current_aio_context(void);
+void qemu_set_current_aio_context(AioContext *ctx);
+
/**
* aio_context_setup:
* @ctx: the aio context
diff --git a/iothread.c b/iothread.c
index 7f086387be..22b967e77c 100644
--- a/iothread.c
+++ b/iothread.c
@@ -39,11 +39,23 @@ DECLARE_CLASS_CHECKERS(IOThreadClass, IOTHREAD,
#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
#endif
-static __thread IOThread *my_iothread;
+static __thread AioContext *my_aiocontext;
+
+void qemu_set_current_aio_context(AioContext *ctx)
+{
+ assert(!my_aiocontext);
+ my_aiocontext = ctx;
+}
AioContext *qemu_get_current_aio_context(void)
{
- return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
+ if (my_aiocontext) {
+ return my_aiocontext;
+ }
+ if (qemu_mutex_iothread_locked()) {
+ return qemu_get_aio_context();
+ }
+ return NULL;
}
static void *iothread_run(void *opaque)
@@ -56,7 +68,7 @@ static void *iothread_run(void *opaque)
* in this new thread uses glib.
*/
g_main_context_push_thread_default(iothread->worker_context);
- my_iothread = iothread;
+ qemu_set_current_aio_context(iothread->ctx);
iothread->thread_id = qemu_get_thread_id();
qemu_sem_post(&iothread->init_done_sem);
diff --git a/stubs/iothread.c b/stubs/iothread.c
index 8cc9e28c55..25ff398894 100644
--- a/stubs/iothread.c
+++ b/stubs/iothread.c
@@ -6,3 +6,7 @@ AioContext *qemu_get_current_aio_context(void)
{
return qemu_get_aio_context();
}
+
+void qemu_set_current_aio_context(AioContext *ctx)
+{
+}
diff --git a/tests/unit/iothread.c b/tests/unit/iothread.c
index afde12b4ef..cab38b3da8 100644
--- a/tests/unit/iothread.c
+++ b/tests/unit/iothread.c
@@ -30,13 +30,26 @@ struct IOThread {
bool stopping;
};
-static __thread IOThread *my_iothread;
+static __thread AioContext *my_aiocontext;
+
+void qemu_set_current_aio_context(AioContext *ctx)
+{
+ assert(!my_aiocontext);
+ my_aiocontext = ctx;
+}
AioContext *qemu_get_current_aio_context(void)
{
- return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
+ if (my_aiocontext) {
+ return my_aiocontext;
+ }
+ if (qemu_mutex_iothread_locked()) {
+ return qemu_get_aio_context();
+ }
+ return NULL;
}
+
static void iothread_init_gcontext(IOThread *iothread)
{
GSource *source;
@@ -54,7 +67,7 @@ static void *iothread_run(void *opaque)
rcu_register_thread();
- my_iothread = iothread;
+ qemu_set_current_aio_context(iothread->ctx);
qemu_mutex_lock(&iothread->init_done_lock);
iothread->ctx = aio_context_new(&error_abort);
diff --git a/util/main-loop.c b/util/main-loop.c
index d9c55df6f5..4ae5b23e99 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -170,6 +170,7 @@ int qemu_init_main_loop(Error **errp)
if (!qemu_aio_context) {
return -EMFILE;
}
+ qemu_set_current_aio_context(qemu_aio_context);
qemu_notify_bh = qemu_bh_new(notify_event_cb, NULL);
gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
src = aio_get_g_source(qemu_aio_context);
If it works for you, I can post it as a formal patch.
Paolo
next prev parent reply other threads:[~2021-05-13 21:06 UTC|newest]
Thread overview: 121+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 8:08 [PATCH v3 00/33] block/nbd: rework client connection Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 01/33] block/nbd: fix channel object leak Vladimir Sementsov-Ogievskiy
2021-05-24 21:31 ` Eric Blake
2021-05-25 4:47 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 02/33] block/nbd: fix how state is cleared on nbd_open() failure paths Vladimir Sementsov-Ogievskiy
2021-04-21 14:00 ` Roman Kagan
2021-04-21 22:27 ` Vladimir Sementsov-Ogievskiy
2021-04-22 8:49 ` Roman Kagan
2021-06-01 21:39 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 03/33] block/nbd: ensure ->connection_thread is always valid Vladimir Sementsov-Ogievskiy
2021-06-01 21:41 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 04/33] block/nbd: nbd_client_handshake(): fix leak of s->ioc Vladimir Sementsov-Ogievskiy
2021-04-22 8:59 ` Roman Kagan
2021-04-16 8:08 ` [PATCH v3 05/33] block/nbd: BDRVNBDState: drop unused connect_err and connect_status Vladimir Sementsov-Ogievskiy
2021-06-01 21:43 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 06/33] util/async: aio_co_schedule(): support reschedule in same ctx Vladimir Sementsov-Ogievskiy
2021-04-23 10:09 ` Roman Kagan
2021-04-26 8:52 ` Vladimir Sementsov-Ogievskiy
2021-05-12 6:56 ` Paolo Bonzini
2021-05-12 7:15 ` Vladimir Sementsov-Ogievskiy
2021-05-13 21:04 ` Paolo Bonzini [this message]
2021-05-14 17:27 ` Roman Kagan
2021-05-14 21:19 ` Paolo Bonzini
2021-06-08 18:45 ` Vladimir Sementsov-Ogievskiy
2021-06-09 9:35 ` Paolo Bonzini
2021-06-09 10:24 ` Vladimir Sementsov-Ogievskiy
2021-06-09 12:17 ` Paolo Bonzini
2021-04-16 8:08 ` [PATCH v3 07/33] block/nbd: simplify waking of nbd_co_establish_connection() Vladimir Sementsov-Ogievskiy
2021-04-27 21:44 ` Roman Kagan
2021-06-02 19:05 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 08/33] block/nbd: drop thr->state Vladimir Sementsov-Ogievskiy
2021-04-27 22:23 ` Roman Kagan
2021-04-28 8:01 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 09/33] block/nbd: bs-independent interface for nbd_co_establish_connection() Vladimir Sementsov-Ogievskiy
2021-06-02 19:14 ` Eric Blake
2021-06-08 10:12 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 10/33] block/nbd: make nbd_co_establish_connection_cancel() bs-independent Vladimir Sementsov-Ogievskiy
2021-06-02 21:18 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 11/33] block/nbd: rename NBDConnectThread to NBDClientConnection Vladimir Sementsov-Ogievskiy
2021-04-27 22:28 ` Roman Kagan
2021-06-02 21:21 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 12/33] block/nbd: introduce nbd_client_connection_new() Vladimir Sementsov-Ogievskiy
2021-06-02 21:22 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 13/33] block/nbd: introduce nbd_client_connection_release() Vladimir Sementsov-Ogievskiy
2021-04-27 22:35 ` Roman Kagan
2021-04-28 8:06 ` Vladimir Sementsov-Ogievskiy
2021-06-02 21:27 ` Eric Blake
2021-06-03 11:59 ` Vladimir Sementsov-Ogievskiy
2021-06-08 10:00 ` Vladimir Sementsov-Ogievskiy
2021-06-08 14:18 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 14/33] nbd: move connection code from block/nbd to nbd/client-connection Vladimir Sementsov-Ogievskiy
2021-04-27 22:45 ` Roman Kagan
2021-04-28 8:14 ` Vladimir Sementsov-Ogievskiy
2021-06-09 15:49 ` Vladimir Sementsov-Ogievskiy
2021-06-03 15:55 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 15/33] nbd/client-connection: use QEMU_LOCK_GUARD Vladimir Sementsov-Ogievskiy
2021-04-28 6:08 ` Roman Kagan
2021-04-28 8:17 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 16/33] nbd/client-connection: add possibility of negotiation Vladimir Sementsov-Ogievskiy
2021-05-11 10:45 ` Roman Kagan
2021-05-12 6:42 ` Vladimir Sementsov-Ogievskiy
2021-06-08 19:23 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 17/33] nbd/client-connection: implement connection retry Vladimir Sementsov-Ogievskiy
2021-05-11 20:54 ` Roman Kagan
2021-06-08 10:24 ` Vladimir Sementsov-Ogievskiy
2021-06-03 16:17 ` Eric Blake
2021-06-03 17:49 ` Vladimir Sementsov-Ogievskiy
2021-06-08 10:38 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:08 ` [PATCH v3 18/33] nbd/client-connection: shutdown connection on release Vladimir Sementsov-Ogievskiy
2021-05-11 21:08 ` Roman Kagan
2021-05-12 6:39 ` Vladimir Sementsov-Ogievskiy
2021-06-03 16:20 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 19/33] block/nbd: split nbd_handle_updated_info out of nbd_client_handshake() Vladimir Sementsov-Ogievskiy
2021-05-12 8:40 ` Roman Kagan
2021-06-03 16:29 ` Eric Blake
2021-06-09 17:23 ` Vladimir Sementsov-Ogievskiy
2021-06-09 18:28 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 20/33] block/nbd: use negotiation of NBDClientConnection Vladimir Sementsov-Ogievskiy
2021-06-03 18:05 ` Eric Blake
2021-04-16 8:08 ` [PATCH v3 21/33] qemu-socket: pass monitor link to socket_get_fd directly Vladimir Sementsov-Ogievskiy
2021-04-19 9:34 ` Daniel P. Berrangé
2021-04-19 10:09 ` Vladimir Sementsov-Ogievskiy
2021-05-12 9:40 ` Roman Kagan
2021-05-12 9:59 ` Daniel P. Berrangé
2021-05-13 11:02 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:09 ` [PATCH v3 22/33] block/nbd: pass monitor directly to connection thread Vladimir Sementsov-Ogievskiy
2021-06-03 18:16 ` Eric Blake
2021-06-03 18:31 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:09 ` [PATCH v3 23/33] block/nbd: nbd_teardown_connection() don't touch s->sioc Vladimir Sementsov-Ogievskiy
2021-06-03 19:04 ` Eric Blake
2021-04-16 8:09 ` [PATCH v3 24/33] block/nbd: drop BDRVNBDState::sioc Vladimir Sementsov-Ogievskiy
2021-06-03 19:12 ` Eric Blake
2021-04-16 8:09 ` [PATCH v3 25/33] nbd/client-connection: return only one io channel Vladimir Sementsov-Ogievskiy
2021-06-03 19:58 ` Eric Blake
2021-04-16 8:09 ` [PATCH v3 26/33] block-coroutine-wrapper: allow non bdrv_ prefix Vladimir Sementsov-Ogievskiy
2021-06-03 20:00 ` Eric Blake
2021-06-03 20:53 ` Eric Blake
2021-06-04 5:29 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:09 ` [PATCH v3 27/33] block/nbd: split nbd_co_do_establish_connection out of nbd_reconnect_attempt Vladimir Sementsov-Ogievskiy
2021-06-03 20:04 ` Eric Blake
2021-06-04 5:30 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:09 ` [PATCH v3 28/33] nbd/client-connection: do qio_channel_set_delay(false) Vladimir Sementsov-Ogievskiy
2021-06-03 20:48 ` Eric Blake
2021-06-04 5:32 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:09 ` [PATCH v3 29/33] nbd/client-connection: add option for non-blocking connection attempt Vladimir Sementsov-Ogievskiy
2021-06-03 20:51 ` Eric Blake
2021-04-16 8:09 ` [PATCH v3 30/33] block/nbd: reuse nbd_co_do_establish_connection() in nbd_open() Vladimir Sementsov-Ogievskiy
2021-06-03 20:57 ` Eric Blake
2021-04-16 8:09 ` [PATCH v3 31/33] block/nbd: add nbd_clinent_connected() helper Vladimir Sementsov-Ogievskiy
2021-05-12 7:06 ` Paolo Bonzini
2021-05-12 7:19 ` Vladimir Sementsov-Ogievskiy
2021-06-03 21:08 ` Eric Blake
2021-04-16 8:09 ` [PATCH v3 32/33] block/nbd: safer transition to receiving request Vladimir Sementsov-Ogievskiy
2021-06-03 21:11 ` Eric Blake
2021-06-04 5:36 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:09 ` [PATCH v3 33/33] block/nbd: drop connection_co Vladimir Sementsov-Ogievskiy
2021-04-16 8:14 ` Vladimir Sementsov-Ogievskiy
2021-04-16 8:21 ` Vladimir Sementsov-Ogievskiy
2021-06-03 21:27 ` Eric Blake
2021-06-04 5:39 ` Vladimir Sementsov-Ogievskiy
2021-05-12 6:54 ` [PATCH v3 00/33] block/nbd: rework client connection Paolo Bonzini
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