Re: [PATCH] KVM: Start lock documentation

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-02-15 17:44, Marcelo Tosatti wrote:
> On Wed, Feb 09, 2011 at 03:11:28PM +0100, Jan Kiszka wrote:
>> The goal of this document shall be
>> - overview of all locks used in KVM core
>> - provide details on the scope of each lock
>> - explain the lock type, specifically of a raw spin locks
>> - provide a lock ordering guide
>>
>> Start with one dependency chain and two locks.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>  Documentation/kvm/locking.txt |   30 ++++++++++++++++++++++++++++++
>>  1 files changed, 30 insertions(+), 0 deletions(-)
>>  create mode 100644 Documentation/kvm/locking.txt
>>
>> diff --git a/Documentation/kvm/locking.txt b/Documentation/kvm/locking.txt
>> new file mode 100644
>> index 0000000..23f9092
>> --- /dev/null
>> +++ b/Documentation/kvm/locking.txt
>> @@ -0,0 +1,30 @@
>> +KVM Lock Overview
>> +=================
>> +
>> +1. Acquisition Orders
>> +---------------------
>> +
>> +kvm_lock
>> ++-> kvm::srcu / kvm::lock
>> +    +-> kvm::slots_lock
>> +        +-> kvm::mmu_lock
>> +...
> 
> Its not easy to understand what you mean here. What kvm_lock has to do
> with the ordering described below it?

kvm_lock is the head of this chain, i.e. there are code paths where it
is taken first, then kvm::lock, etc.

Jan

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