From: Markus Armbruster <armbru@redhat.com>
To: qemu-devel@nongnu.org
Cc: kwolf@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>
Subject: [PULL 12/14] block: Add bdrv_co_enter()/leave()
Date: Fri, 9 Oct 2020 08:34:30 +0200 [thread overview]
Message-ID: <20201009063432.303441-13-armbru@redhat.com> (raw)
In-Reply-To: <20201009063432.303441-1-armbru@redhat.com>
From: Kevin Wolf <kwolf@redhat.com>
Add a pair of functions to temporarily move the current coroutine to the
AioContext of a given BlockDriverState.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201005155855.256490-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
include/block/block.h | 17 +++++++++++++++++
block.c | 23 +++++++++++++++++++++++
2 files changed, 40 insertions(+)
diff --git a/include/block/block.h b/include/block/block.h
index ce2ac39299..1027c58a41 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -640,6 +640,23 @@ bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag);
*/
AioContext *bdrv_get_aio_context(BlockDriverState *bs);
+/**
+ * Move the current coroutine to the AioContext of @bs and return the old
+ * AioContext of the coroutine. Increase bs->in_flight so that draining @bs
+ * will wait for the operation to proceed until the corresponding
+ * bdrv_co_leave().
+ *
+ * Consequently, you can't call drain inside a bdrv_co_enter/leave() section as
+ * this will deadlock.
+ */
+AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs);
+
+/**
+ * Ends a section started by bdrv_co_enter(). Move the current coroutine back
+ * to old_ctx and decrease bs->in_flight again.
+ */
+void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx);
+
/**
* Transfer control to @co in the aio context of @bs
*/
diff --git a/block.c b/block.c
index 52b2e2709f..8d9b9017d3 100644
--- a/block.c
+++ b/block.c
@@ -6303,6 +6303,29 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs)
return bs ? bs->aio_context : qemu_get_aio_context();
}
+AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs)
+{
+ Coroutine *self = qemu_coroutine_self();
+ AioContext *old_ctx = qemu_coroutine_get_aio_context(self);
+ AioContext *new_ctx;
+
+ /*
+ * Increase bs->in_flight to ensure that this operation is completed before
+ * moving the node to a different AioContext. Read new_ctx only afterwards.
+ */
+ bdrv_inc_in_flight(bs);
+
+ new_ctx = bdrv_get_aio_context(bs);
+ aio_co_reschedule_self(new_ctx);
+ return old_ctx;
+}
+
+void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
+{
+ aio_co_reschedule_self(old_ctx);
+ bdrv_dec_in_flight(bs);
+}
+
void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co)
{
aio_co_enter(bdrv_get_aio_context(bs), co);
--
2.26.2
next prev parent reply other threads:[~2020-10-09 6:44 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-09 6:34 [PULL 00/14] Monitor patches for 2020-10-09 Markus Armbruster
2020-10-09 6:34 ` [PULL 01/14] monitor: Add Monitor parameter to monitor_set_cpu() Markus Armbruster
2020-10-09 6:34 ` [PULL 02/14] monitor: Add Monitor parameter to monitor_get_cpu_index() Markus Armbruster
2020-10-09 6:34 ` [PULL 03/14] monitor: Use getter/setter functions for cur_mon Markus Armbruster
2020-10-09 6:34 ` [PULL 04/14] hmp: Update current monitor only in handle_hmp_command() Markus Armbruster
2020-10-09 6:34 ` [PULL 05/14] qmp: Assert that no other monitor is active Markus Armbruster
2020-10-09 6:34 ` [PULL 06/14] qmp: Call monitor_set_cur() only in qmp_dispatch() Markus Armbruster
2020-10-09 6:34 ` [PULL 07/14] monitor: Make current monitor a per-coroutine property Markus Armbruster
2020-10-09 6:34 ` [PULL 08/14] qapi: Add a 'coroutine' flag for commands Markus Armbruster
2020-10-09 6:34 ` [PULL 09/14] qmp: Move dispatcher to a coroutine Markus Armbruster
2020-10-12 10:47 ` Alex Bennée
2020-10-12 11:25 ` Kevin Wolf
2020-10-12 11:53 ` Philippe Mathieu-Daudé
2020-10-12 12:47 ` Kevin Wolf
2020-10-12 15:02 ` Alex Bennée
2020-10-12 18:49 ` Ben Widawsky
2020-10-13 7:56 ` Philippe Mathieu-Daudé
2020-10-13 11:29 ` Kevin Wolf
2020-10-17 8:15 ` Volker Rümelin
2020-10-19 8:57 ` Kevin Wolf
2020-10-19 18:24 ` Volker Rümelin
2020-10-09 6:34 ` [PULL 10/14] hmp: Add support for coroutine command handlers Markus Armbruster
2020-10-09 6:34 ` [PULL 11/14] util/async: Add aio_co_reschedule_self() Markus Armbruster
2020-10-09 6:34 ` Markus Armbruster [this message]
2020-10-09 6:34 ` [PULL 13/14] block: Add bdrv_lock()/unlock() Markus Armbruster
2020-10-09 6:34 ` [PULL 14/14] block: Convert 'block_resize' to coroutine Markus Armbruster
2020-10-09 13:47 ` [PULL 00/14] Monitor patches for 2020-10-09 Peter Maydell
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