Re: Documentation of the kvm->srcu lock

[Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>]

On 09/09/2013 08:13 PM, Paolo Bonzini wrote:
> Il 09/09/2013 14:00, Thomas Huth ha scritto:
>>
>>  Hi all!
>>
>> I am quite new to KVM, and I recently had to struggle with the
>> kvm->srcu lock a little bit ... documentation for this lock seems
>> to be quite sparse, I've only found some descriptions in mailing
>> list archives (the description at the following URL is quite good:
>> http://www.mail-archive.com/kvm@vger.kernel.org/msg90003.html ).
>>
>> So I wonder whether it would be helpful for others, too, if some
>> information about this lock was added to the documentation file
>> Documentation/virtual/kvm/locking.txt for example? I'd like to
>> suggest the following text as a first draft (using some information
>> from the URL above):
>>
>>  Name:		kvm->srcu
>>  Type:		srcu lock
>>  Arch:		any
>>  Protects:	- kvm->memslots
>>  		- kvm->buses
>>  Comment:	The srcu read lock must be held while accessing memslots (e.g.
>>  		when using gfn_to_* functions) and while accessing in-kernel
>>  		MMIO/PIO address->device structure mapping (kvm->buses).
>>  		The srcu index can be stored in kvm_vcpu->srcu_idx per vcpu
>>  		if it is needed by multiple functions.
>>
>> What do you think? Since I am not an expert in this area, extension
>> and/or corrections are very welcome!
> 
> Yes, this looks good.  Xiao, any suggestions?

It's nice indeed! :)

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>