Am 07.09.2023 um 20:40 hat Stefan Hajnoczi geschrieben: > On Tue, Sep 05, 2023 at 04:50:02PM +0200, Kevin Wolf wrote: > > virtio_load() as a whole should run in coroutine context because it > > reads from the migration stream and we don't want this to block. > > Is that "should" a "must" or a "can"? > > If it's a "must" then virtio_load() needs assert(qemu_in_coroutine()). > > But the previous patch mentioned that loadvm for snapshots calls it > outside coroutine context. So maybe it's a "can"?
Where this makes a difference is when the function indirectly calls into QIOChannel. When called from a coroutine, it yields while waiting for I/O, and outside of a coroutine it blocks. Yielding is always preferable, but in cases like HMP savevm/loadvm we also don't really care because it's synchronous anyway. Whether that makes it a MAY or a SHOULD in the RFC sense, you decide. If you wanted to make it a MUST, you'd need to check all callers first and change some of them. Kevin
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