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ptrace: ptrace_check_attach(): rename @kill to @ignore_state and add comments 

PTRACE_INTERRUPT is going to be added which should also skip
task_is_traced() check in ptrace_check_attach().  Rename @kill to
@ignore_state and make it bool.  Add function comment while at it.

This patch doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
This commit is contained in:
Tejun Heo 2011-06-02 11:13:59 +02:00 committed by Oleg Nesterov
parent a8f072c1d6
commit 755e276b33
2 changed files with 20 additions and 6 deletions
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2
include/linux/ptrace.h
View File

@ -105,7 +105,7 @@ extern long arch_ptrace(struct task_struct *child, long request,
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
extern void ptrace_disable(struct task_struct *);
extern int ptrace_check_attach(struct task_struct *task, int kill);
extern int ptrace_check_attach(struct task_struct *task, bool ignore_state);
extern int ptrace_request(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
extern void ptrace_notify(int exit_code);

24
kernel/ptrace.c
View File

@ -97,10 +97,24 @@ void __ptrace_unlink(struct task_struct *child)
spin_unlock(&child->sighand->siglock);
}
/*
* Check that we have indeed attached to the thing..
/**
* ptrace_check_attach - check whether ptracee is ready for ptrace operation
* @child: ptracee to check for
* @ignore_state: don't check whether @child is currently %TASK_TRACED
*
* Check whether @child is being ptraced by %current and ready for further
* ptrace operations. If @ignore_state is %false, @child also should be in
* %TASK_TRACED state and on return the child is guaranteed to be traced
* and not executing. If @ignore_state is %true, @child can be in any
* state.
*
* CONTEXT:
* Grabs and releases tasklist_lock and @child->sighand->siglock.
*
* RETURNS:
* 0 on success, -ESRCH if %child is not ready.
*/
int ptrace_check_attach(struct task_struct *child, int kill)
int ptrace_check_attach(struct task_struct *child, bool ignore_state)
{
int ret = -ESRCH;
@ -119,13 +133,13 @@ int ptrace_check_attach(struct task_struct *child, int kill)
*/
spin_lock_irq(&child->sighand->siglock);
WARN_ON_ONCE(task_is_stopped(child));
if (task_is_traced(child) || kill)
if (task_is_traced(child) || ignore_state)
ret = 0;
spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
if (!ret && !kill)
if (!ret && !ignore_state)
ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
/* All systems go.. */