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authorStefan Hajnoczi <stefanha@redhat.com>2023-05-16 15:02:29 -0400
committerKevin Wolf <kwolf@redhat.com>2023-05-30 17:32:02 +0200
commitf6eac904f6825d47adc6102c8d7b59b8ba5b778e (patch)
tree5b1faf62077883c92fd8619063bd3738680c20e0 /hw/xen
parentab61335025b1274bd7042219203524045b23e0d3 (diff)
downloadfocaccia-qemu-f6eac904f6825d47adc6102c8d7b59b8ba5b778e.tar.gz
focaccia-qemu-f6eac904f6825d47adc6102c8d7b59b8ba5b778e.zip
xen-block: implement BlockDevOps->drained_begin()
Detach event channels during drained sections to stop I/O submission
from the ring. xen-block is no longer reliant on aio_disable_external()
after this patch. This will allow us to remove the
aio_disable_external() API once all other code that relies on it is
converted.

Extend xen_device_set_event_channel_context() to allow ctx=NULL. The
event channel still exists but the event loop does not monitor the file
descriptor. Event channel processing can resume by calling
xen_device_set_event_channel_context() with a non-NULL ctx.

Factor out xen_device_set_event_channel_context() calls in
hw/block/dataplane/xen-block.c into attach/detach helper functions.
Incidentally, these don't require the AioContext lock because
aio_set_fd_handler() is thread-safe.

It's safer to register BlockDevOps after the dataplane instance has been
created. The BlockDevOps .drained_begin/end() callbacks depend on the
dataplane instance, so move the blk_set_dev_ops() call after
xen_block_dataplane_create().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230516190238.8401-12-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'hw/xen')
-rw-r--r--hw/xen/xen-bus.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index c59850b1de..b8f408c9ed 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -846,8 +846,11 @@ void xen_device_set_event_channel_context(XenDevice *xendev,
                            NULL, NULL, NULL, NULL, NULL);
 
     channel->ctx = ctx;
-    aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), true,
-                       xen_device_event, NULL, xen_device_poll, NULL, channel);
+    if (ctx) {
+        aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh),
+                           true, xen_device_event, NULL, xen_device_poll, NULL,
+                           channel);
+    }
 }
 
 XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,