[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v3 01/16] perf: Ensure perf_guest_cbs aren't reloaded between !NULL check and deref
- To: Sean Christopherson <seanjc@xxxxxxxxxx>, Like Xu <like.xu.linux@xxxxxxxxx>
- From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
- Date: Wed, 10 Nov 2021 12:07:54 +0100
- Authentication-results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@xxxxxxxxxx
- Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>, Jiri Olsa <jolsa@xxxxxxxxxx>, Namhyung Kim <namhyung@xxxxxxxxxx>, James Morse <james.morse@xxxxxxx>, Alexandru Elisei <alexandru.elisei@xxxxxxx>, Suzuki K Poulose <suzuki.poulose@xxxxxxx>, Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>, Wanpeng Li <wanpengli@xxxxxxxxxxx>, Jim Mattson <jmattson@xxxxxxxxxx>, Joerg Roedel <joro@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-perf-users@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, kvmarm@xxxxxxxxxxxxxxxxxxxxx, linux-csky@xxxxxxxxxxxxxxx, linux-riscv@xxxxxxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, Artem Kashkanov <artem.kashkanov@xxxxxxxxx>, Zhu Lingshan <lingshan.zhu@xxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Albert Ou <aou@xxxxxxxxxxxxxxxxx>, Palmer Dabbelt <palmer@xxxxxxxxxxx>, Vincent Chen <deanbo422@xxxxxxxxx>, Paul Walmsley <paul.walmsley@xxxxxxxxxx>, Greentime Hu <green.hu@xxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Marc Zyngier <maz@xxxxxxxxxx>, Nick Hu <nickhu@xxxxxxxxxxxxx>, Guo Ren <guoren@xxxxxxxxxx>, Mark Rutland <mark.rutland@xxxxxxx>, Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
- Delivery-date: Wed, 10 Nov 2021 11:08:24 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 11/4/21 15:18, Sean Christopherson wrote:
If I'm interpeting Paolo's suggestion
correctly, he's pointing out that oustanding stores to the function pointers in
@cbs need to complete before assigning a non-NULL pointer to perf_guest_cbs,
otherwise a perf event handler may see a valid pointer with half-baked
callbacks.
I think smp_store_release() with a comment would be appropriate, assuming my
above interpretation is correct.
Yes, exactly. It should even be rcu_assign_pointer(), matching the
synchronize_rcu() in patch 1 (and the change can be done in patch 1, too).
Paolo
|