Re: [PATCH] KVM: Start lock documentation

[Avi Kivity <avi@redhat.com>]

On 02/15/2011 06:44 PM, 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?
>

Yeah, I meant to make the same comment but forgot.  I suggest a union of 
paths:

   kvm::srcu (read) -> { fields }
| kvm::slots_lock(write) -> { fields }

but let's start with the reference section.