UTRACE_PREPARE_EXAMI(9) utrace core API UTRACE_PREPARE_EXAMI(9)NAMEutrace_prepare_examine - prepare to examine thread state
SYNOPSIS
int utrace_prepare_examine(struct task_struct * target,
struct utrace_engine * engine,
struct utrace_examiner * exam);
ARGUMENTS
target
thread of interest, a struct task_struct pointer
engine
engine pointer returned by utrace_attach_task
exam
temporary state, a struct utrace_examiner pointer
DESCRIPTION
This call prepares to safely examine the thread target using struct
user_regset calls, or direct access to thread-synchronous fields.
When target is current, this call is superfluous. When target is
another thread, it must be held stopped via UTRACE_STOP by engine.
This call may block the caller until target stays stopped, so it must
be called only after the caller is sure target is about to unschedule.
This means a zero return from a utrace_control call on engine giving
UTRACE_STOP, or a report_quiesce or report_signal callback to engine
that used UTRACE_STOP in its return value.
Returns -ESRCH if target is dead or -EINVAL if UTRACE_STOP was not
used. If target has started running again despite UTRACE_STOP (for
SIGKILL or a spurious wakeup), this call returns -EAGAIN.
When this call returns zero, it´s safe to use struct user_regset calls
and task_user_regset_view on target and to examine some of its fields
directly. When the examination is complete, a utrace_finish_examine
call must follow to check whether it was completed safely.
Kernel Hackers Manual 2.6. November 2013 UTRACE_PREPARE_EXAMI(9)
