Messages in this thread | | | Subject | Re: [PATCH v2] um: read multiple msg from virtio slave request fd | From | Johannes Berg <> | Date | Tue, 09 Aug 2022 20:07:47 +0200 |
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On Tue, 2022-06-07 at 11:27 +0000, Benjamin Beichler wrote: > If VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS is activated, the user mode > linux virtio irq handler only read one msg from the corresponding socket. > This creates issues, when the device emulation creates multiple call > requests (e.g. for multiple virtqueues), as the socket buffer tend to fill > up and the call requests are delayed. > > This creates a deadlock situation, when the device simulation blocks, > because of sending a msg and the kernel side blocks because of > synchronously waiting for an acknowledge of kick request. > > Actually inband notifications are meant to be used in combination with the > time travel protocol, but it is not required, therefore this corner case > needs to be handled. > > Anyways, in general it seems to be more natural to consume always all > messages from a socket, instead of only a single one. > > Fixes: 2cd097ba8c05 ("um: virtio: Implement VHOST_USER_PROTOCOL_F_SLAVE_REQ") > Signed-off-by: Benjamin Beichler <benjamin.beichler@uni-rostock.de> >
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Sorry, should've sent that earlier.
johannes
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