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Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module? |
Date: |
Mon, 12 May 2014 13:18:44 +0300 |
On Mon, May 12, 2014 at 12:14:25PM +0200, Paolo Bonzini wrote:
> Il 12/05/2014 12:08, Michael S. Tsirkin ha scritto:
> >On Mon, May 12, 2014 at 11:57:32AM +0200, Paolo Bonzini wrote:
> >>Perhaps we can check for cases where only the address is changing,
> >>and poke at an existing struct kvm_kernel_irq_routing_entry without
> >>doing any RCU synchronization?
> >
> >I suspect interrupts can get lost then: e.g. if address didn't match any
> >cpus, now it matches some. No?
>
> Can you explain the problem more verbosely? :)
>
> Multiple writers would still be protected by the mutex, so you
> cannot have an "in-place update" writer racing with a "copy the
> array" writer.
>
> Paolo
I am not sure really.
I'm worried about reader vs writer.
If reader sees a stale msi value msi will be sent to a wrong
address.
- [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Gonglei (Arei), 2014/05/08
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/09
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Gonglei (Arei), 2014/05/09
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/09
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Gonglei (Arei), 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Michael S. Tsirkin, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Michael S. Tsirkin, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Michael S. Tsirkin, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Michael S. Tsirkin, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Paolo Bonzini, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Michael S. Tsirkin, 2014/05/12
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Gonglei (Arei), 2014/05/13
- Re: [Qemu-devel] [RFC] vhost: Can we change synchronize_rcu to call_rcu in vhost_set_memory() in vhost kernel module?, Michael S. Tsirkin, 2014/05/13