audit function doc. question

[randy_dunlap]

kernel/audit.c (2.6.13-rc1-git5) audit_log_start() says:

/* Obtain an audit buffer.  This routine does locking to obtain the
 * audit buffer, but then no locking is required for calls to
 * audit_log_*format.  If the tsk is a task that is currently in a
 * syscall, then the syscall is marked as auditable and an audit record
 * will be written at syscall exit.  If there is no associated task, tsk
 * should be NULL. */
struct audit_buffer *audit_log_start(struct audit_context *ctx, int type)
{


What does <tsk> refer to in the function description?
There is no <tsk> in this function.

Thanks,
---
~Randy