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Subject[PATCH 3/9] ptrace: ptrace_check_attach(): rename @kill to @ignore_state and add comments
Date
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>
---
include/linux/ptrace.h | 2 +-
kernel/ptrace.c | 24 +++++++++++++++++++-----
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index a1147e5..974e187 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -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);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 30de03b..5cd77a8 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -96,10 +96,24 @@ 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;

@@ -118,13 +132,13 @@ 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.. */
--
1.7.1


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