* [Qemu-devel] rcu kicking CPU threads before they're set up...
@ 2015-03-11 10:23 Peter Maydell
2015-03-11 14:06 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Peter Maydell @ 2015-03-11 10:23 UTC (permalink / raw)
To: QEMU Developers; +Cc: Paolo Bonzini
I noticed this while I was trying to debug something and so was
single stepping through the CPU realize function.
The rcu thread seems to get set up and try to start working too
early in QEMU's initialization process. Specifically, it can try
to do things before we've completed the creation and init of all
the CPUs: I'm seeing call_rcu_thread() calling qemu_mutex_lock_iothread()
calling qemu_cpu_kick_thread() before we've even finished actually
creating and realizing the CPU objects. This segfaults because
cpu->thread isn't set yet.
-- PMM
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] rcu kicking CPU threads before they're set up...
2015-03-11 10:23 [Qemu-devel] rcu kicking CPU threads before they're set up Peter Maydell
@ 2015-03-11 14:06 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2015-03-11 14:06 UTC (permalink / raw)
To: Peter Maydell, QEMU Developers
On 11/03/2015 11:23, Peter Maydell wrote:
> I noticed this while I was trying to debug something and so was
> single stepping through the CPU realize function.
>
> The rcu thread seems to get set up and try to start working too
> early in QEMU's initialization process. Specifically, it can try
> to do things before we've completed the creation and init of all
> the CPUs: I'm seeing call_rcu_thread() calling qemu_mutex_lock_iothread()
> calling qemu_cpu_kick_thread() before we've even finished actually
> creating and realizing the CPU objects. This segfaults because
> cpu->thread isn't set yet.
Should be fixed by now:
commit 6b49809c597331803ea941eadda813e5bb4e8fe2
Author: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri Feb 27 19:58:23 2015 +0100
cpus: fix deadlock and segfault in qemu_mutex_lock_iothread
commit 21618b3e55ad2c6fede0bffcaea466091811ce59
Author: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri Feb 27 20:01:03 2015 +0100
cpus: be more paranoid in avoiding deadlocks
Paolo
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2015-03-11 10:23 [Qemu-devel] rcu kicking CPU threads before they're set up Peter Maydell
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