Re: [PATCH v6] Work around vhost-user-blk-test hang

[Stefan Hajnoczi]

On Thu, Oct 14, 2021 at 04:32:23AM +0000, Raphael Norwitz wrote:
> The vhost-user-blk-test qtest has been hanging intermittently for a
> while. The root cause is not yet fully understood, but the hang is
> impacting enough users that it is important to merge a workaround for
> it.
> 
> The race which causes the hang occurs early on in vhost-user setup,
> where a vhost-user message is never received by the backend. Forcing
> QEMU to wait until the storage-daemon has had some time to initialize
> prevents the hang. Thus the existing storage-daemon pidfile option can
> be used to implement a workaround cleanly and effectively, since it
> creates a file only once the storage-daemon initialization is complete.
> 
> This change implements a workaround for the vhost-user-blk-test hang by
> making QEMU wait until the storage-daemon has written out a pidfile
> before attempting to connect and send messages over the vhost-user
> socket.
> 
> Some relevent mailing list discussions:
> 
> [1] 
> https://lore.kernel.org/qemu-devel/CAFEAcA8kYpz9LiPNxnWJAPSjc=nv532bEdyfynaBeMeohqBp3A@mail.gmail.com/
> [2] 
> https://lore.kernel.org/qemu-devel/YWaky%2FKVbS%2FKZjlV@stefanha-x1.localdomain/

I sent a fix for the hang so the workaround is no longer needed:
"[PATCH] vhost-user-blk-test: pass vhost-user socket fds to QSD"

Stefan

signature.asc
Description: PGP signature