ACC Programmer's Reference Guide

Chapter 3 127
ZCOM Tables and Data Structures
ZCOM Kernel Data
ZC_SLOCK - Super IFT spinlock
This lock protects against deadlock situations while multiple IFTs need
to be access simultaneously. A piece of code must obtain this lock first if
it is going to lock multiple IFTs.
Each of the above fields is a data structure (zlock_t) with the data fields
shown in Table 3-52.
LOCKP - Pointer to kernel spinlock structure
This is a pointer to the spinlock structure allocated dynamically from the
kernel. It is used for the locking mechanism in the kernel.
REFCOUNT - Lock reference count
This is to support locks that could be acquired recursively in the ZCOM
subsystem. Every t ime when the ZCOM lock is acquired, this count is
incremented. When the ZCOM lock is released, this count is
decremented. Only when this count reaches zero, t he kernel lock (via the
LOCKP pointer) is released.
Table 3-52 Super IFT spinlock (ZC_SLOCK) Data Structure
Field Name Field Description Field Type Size
(Bytes)
LOCKP Pointer to kernel spinlock structure pointer 8
REFCOUNT Lock reference count int 4
SPARE1 Reserved, not used int 4