KSession

class KSession extends KAutoObject;

Size : 0x4C bytes

Offset	Type	Description
0x0	u32	Pointer to vtable
0x4	u32	Reference count
0x20	KThread*	X ?
0x24	KThread*	Y ?
0x2C	KThread*	Z ?

It seems X=Y=Z. X, Y and Z can be NULL.

Structure for at least 5.0.0-11 NATIVE_FIRM upward:

Size : 0x4C bytes (KAutoObject, KServerSession, KClientSession, sequentially):

Offset	Type		Description
0x0	KAutoObject	u32	Pointer to vtable
0x4		u32	Reference count
0x8	KServerSession	u32	Pointer to vtable
0xC		u32	Reference count
0x10		u32	KLinkedListNode count for sync threads
0x14		KLinkedListNode*	Pointer to first KLinkedListNode in the list of threads that sync with this object
0x18		KLinkedListNode*	Pointer to last KLinkedListNode in the list of threads that sync with this object
0x1C		KSession*	Pointer to parent session
0x20		KThread*	Last stolen KThread during sync request- current thread when KServerSession code is running during svc - noted in KThread+0xA8 as well
0x24		KThread*	First stolen KThread during sync request
0x28		KThread*	KThread that originated the session
0x2C	KClientSession	u32	Pointer to vtable
0x30		u32	Reference count
0x34		u32	KLinkedListNode count for sync threads
0x38		KLinkedListNode*	Pointer to first KLinkedListNode in the list of threads that sync with this object
0x3C		KLinkedListNode*	Pointer to last KLinkedListNode in the list of threads that sync with this object
0x40		KSession*	Pointer to parent session
0x44		u32	Session status
0x48		KClientPort*	Pointer to associated client port inside parent KPort

Session status:

1: open
2: closed by client
3: closed by server?