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Commit 6b39c7bf authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

kill PT_ATTACHED 



Since the patch

	"Fix ptrace_attach()/ptrace_traceme()/de_thread() race"
	commit f5b40e36

we set PT_ATTACHED and change child->parent "atomically" wrt task_list lock.

This means we can remove the checks like "PT_ATTACHED && ->parent != ptracer"
which were needed to catch the "ptrace attach is in progress" case.  We can
also remove the flag itself since nobody else uses it.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 01b8b07a

include/linux/ptrace.h

+0 −1
Original line number Diff line number Diff line
@@ -67,7 +67,6 @@ 
#define PT_TRACE_EXEC	0x00000080

#define PT_TRACE_VFORK_DONE	0x00000100

#define PT_TRACE_EXIT	0x00000200

#define PT_ATTACHED	0x00000400	/* parent != real_parent */



#define PT_TRACE_MASK	0x000003f4

kernel/exit.c

+1 −12
Original line number Diff line number Diff line
@@ -1514,18 +1514,7 @@ static int wait_task_continued(struct task_struct *p, int noreap, 


static inline int my_ptrace_child(struct task_struct *p)

{

	if (!(p->ptrace & PT_PTRACED))

		return 0;

	if (!(p->ptrace & PT_ATTACHED))

		return 1;

	/*

	 * This child was PTRACE_ATTACH'd.  We should be seeing it only if

	 * we are the attacher.  If we are the real parent, this is a race

	 * inside ptrace_attach.  It is waiting for the tasklist_lock,

	 * which we have to switch the parent links, but has already set

	 * the flags in p->ptrace.

	 */

	return (p->parent != p->real_parent);

	return p->ptrace & PT_PTRACED;

}



static long do_wait(pid_t pid, int options, struct siginfo __user *infop,

kernel/ptrace.c

+2 −4
Original line number Diff line number Diff line
@@ -100,8 +100,7 @@ int ptrace_check_attach(struct task_struct *child, int kill) 
	 */

	read_lock(&tasklist_lock);

	if ((child->ptrace & PT_PTRACED) && child->parent == current &&

	    (!(child->ptrace & PT_ATTACHED) || child->real_parent != current)

	    && child->signal != NULL) {

	     child->signal != NULL) {

		ret = 0;

		spin_lock_irq(&child->sighand->siglock);

		if (task_is_stopped(child))
@@ -200,8 +199,7 @@ repeat: 
		goto bad;



	/* Go */

	task->ptrace |= PT_PTRACED | ((task->real_parent != current)

				      ? PT_ATTACHED : 0);

	task->ptrace |= PT_PTRACED;

	if (capable(CAP_SYS_PTRACE))

		task->ptrace |= PT_PTRACE_CAP;

kernel/signal.c

+0 −5
Original line number Diff line number Diff line
@@ -1556,11 +1556,6 @@ static inline int may_ptrace_stop(void) 
{

	if (!likely(current->ptrace & PT_PTRACED))

		return 0;



	if (unlikely(current->parent == current->real_parent &&

		    (current->ptrace & PT_ATTACHED)))

		return 0;



	/*

	 * Are we in the middle of do_coredump?

	 * If so and our tracer is also part of the coredump stopping