Documentation of the kvm->srcu lock

[Thomas Huth <thuth@linux.vnet.ibm.com>]

 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!

 Regards,
  Thomas