[PATCH v5 13/21] hw/xen: do not set is_external=true on evtchn fds

[Stefan Hajnoczi]

is_external=true suspends fd handlers between aio_disable_external() and
aio_enable_external(). The block layer's drain operation uses this
mechanism to prevent new I/O from sneaking in between
bdrv_drained_begin() and bdrv_drained_end().

The previous commit converted the xen-block device to use BlockDevOps
.drained_begin/end() callbacks. It no longer relies on is_external=true
so it is safe to pass is_external=false.

This is part of ongoing work to remove the aio_disable_external() API.

Signed-off-by: Stefan Hajnoczi 
---
 hw/xen/xen-bus.c | 8 
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index b8f408c9ed..bf256d4da2 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -842,14 +842,14 @@ void xen_device_set_event_channel_context(XenDevice 
*xendev,
 }
 
 if (channel->ctx)
-aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), 
true,
+aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), 
false,
NULL, NULL, NULL, NULL, NULL);
 
 channel->ctx = ctx;
 if (ctx) {
 aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh),
-   true, xen_device_event, NULL, xen_device_poll, NULL,
-   channel);
+   false, xen_device_event, NULL, xen_device_poll,
+   NULL, channel);
 }
 }
 
@@ -923,7 +923,7 @@ void xen_device_unbind_event_channel(XenDevice *xendev,
 
 QLIST_REMOVE(channel, list);
 
-aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), true,
+aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), false,
NULL, NULL, NULL, NULL, NULL);
 
 if (qemu_xen_evtchn_unbind(channel->xeh, channel->local_port) < 0) {
-- 
2.40.1

Re: [PATCH v5 13/21] hw/xen: do not set is_external=true on evtchn fds

[Anthony PERARD]

On Thu, May 04, 2023 at 03:53:19PM -0400, Stefan Hajnoczi wrote:
> is_external=true suspends fd handlers between aio_disable_external() and
> aio_enable_external(). The block layer's drain operation uses this
> mechanism to prevent new I/O from sneaking in between
> bdrv_drained_begin() and bdrv_drained_end().
> 
> The previous commit converted the xen-block device to use BlockDevOps
> .drained_begin/end() callbacks. It no longer relies on is_external=true
> so it is safe to pass is_external=false.
> 
> This is part of ongoing work to remove the aio_disable_external() API.
> 
> Signed-off-by: Stefan Hajnoczi 

Acked-by: Anthony PERARD 

Thanks,

-- 
Anthony PERARD