Re: [PATCH 0/2] block: Allow concurrent BB context changes

[Michael Tokarev]

09.02.2024 19:51, Hanna Czenczek :
> On 09.02.24 15:08, Michael Tokarev wrote:
> > 02.02.2024 17:47, Hanna Czenczek :
> > > Hi,
> > >
> > > Without the AioContext lock, a BB's context may kind of change at any
> > > time (unless it has a root node, and I/O requests are pending). That
> > > also means that its own context (BlockBackend.ctx) and that of its root
> > > node can differ sometimes (while the context is being changed).
> >
> > How relevant this is for -stable (8.2 at least) which does not have
> > "scsi: eliminate AioContext lock" patchset, and in particular,:
> > v8.2.0-124-geaad0fe260 "scsi: only access SCSIDevice->requests from
> > one thread"?
> >
> > The issue first patch "block-backend: Allow concurrent context changes"
> > fixes (RHEL-19381) seems to be for 8.1.something, so it exists in 8.2
> > too, and this particular fix applies to 8.2.
> >
> > But with other changes around all this, I'm a bit lost as of what should
> > be done on stable.  Not even thinking about 7.2 here :)
>
> Ah, sorry, yes.  Since we do still have the AioContext lock, this series won’t 
> be necessary in -stable.  Sorry for the noise!

Hm. Now I'm confused even more.. :)

ad89367202 "block-backend: Allow concurrent context changes" - the first
one in this series - apparently is needed, as it fixes an issue reported
for qemu 8.1 (https://issues.redhat.com/browse/RHEL-19381).  Or is it not
the case?

FWIW, truth is born in the noise, not in silence ;)

Thanks,

/mjt