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Re: [Qemu-devel] [PATCH] exec.c: ensure all AddressSpaceDispatch updates
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] exec.c: ensure all AddressSpaceDispatch updates under RCU |
Date: |
Mon, 24 Oct 2016 16:17:02 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 |
On 21/10/2016 17:34, Alex Bennée wrote:
> The memory_dispatch field is meant to be protected by RCU so we should
> use the correct primitives when accessing it. This race was flagged up
> by the ThreadSanitizer.
>
> Signed-off-by: Alex Bennée <address@hidden>
> ---
> exec.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 738e8ba..c5e4073 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -459,7 +459,7 @@ address_space_translate_for_iotlb(CPUState *cpu, int
> asidx, hwaddr addr,
> hwaddr *xlat, hwaddr *plen)
> {
> MemoryRegionSection *section;
> - AddressSpaceDispatch *d = cpu->cpu_ases[asidx].memory_dispatch;
> + AddressSpaceDispatch *d =
> atomic_rcu_read(&cpu->cpu_ases[asidx].memory_dispatch);
>
> section = address_space_translate_internal(d, addr, xlat, plen, false);
>
> @@ -2342,7 +2342,7 @@ static void tcg_commit(MemoryListener *listener)
> * may have split the RCU critical section.
> */
> d = atomic_rcu_read(&cpuas->as->dispatch);
> - cpuas->memory_dispatch = d;
> + atomic_rcu_set(&cpuas->memory_dispatch, d);
> tlb_flush(cpuas->cpu, 1);
> }
>
>
Oops, this missed today's pull request but it's a bug so it can go in later.
Thanks,
Paolo