Messages in this thread | | | Date | Wed, 25 Feb 2015 11:29:32 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH for stable] x86/spinlocks/paravirt: Fix memory corruption on unlock |
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* Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> > By all means! > > > > You'll first need to cherry-pick these commits: > > > 927609d622a3 kernel: tighten rules for ACCESS ONCE > > c5b19946eb76 kernel: Fix sparse warning for ACCESS_ONCE > > dd36929720f4 kernel: make READ_ONCE() valid on const arguments > > If you go before 3.19, you will also need > > 230fa253df63 kernel: Provide READ_ONCE and ASSIGN_ONCE > 43239cbe79fc kernel: Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)
The affected spinlock code went over several iterations post v3.18, which I think makes the spinlock change too risky and complex to backport so far back. So it's not necessay to backport these READ_ONCE() changes.
> > That's the minimum set you will need for backporting, > > due to overlapping changes to the ACCESS_ONCE() > > definition. > > > > and then apply this commit: > > > > d6abfdb20223 x86/spinlocks/paravirt: Fix memory corruption on unlock > > the alternative might be to replace READ_ONCE with > ACCESS_ONCE when doing the backport.
Doing changes to patches when doing a backport is a big no-no IMHO. Either there is a clean sequence of upstream commit IDs to cherry-pick, or it should not be backported in most cases.
Thanks,
Ingo
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