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authorOleg Nesterov <oleg@tv-sign.ru>2008-02-08 07:18:58 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 12:22:26 -0500
commit6b39c7bfbd1436836c0fb34c5b437fda1a7a3dd4 (patch)
tree60d3d9719eef3076527fcbf9c3cb362fe0f52d61
parent01b8b07a5d77d22e609267dcae74d15e3e9c5f13 (diff)
kill PT_ATTACHED
Since the patch "Fix ptrace_attach()/ptrace_traceme()/de_thread() race" commit f5b40e363ad6041a96e3da32281d8faa191597b9 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: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Roland McGrath <roland@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/ptrace.h1
-rw-r--r--kernel/exit.c13
-rw-r--r--kernel/ptrace.c6
-rw-r--r--kernel/signal.c5
4 files changed, 3 insertions, 22 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 6ab80714a916..ebe0c17039cf 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -67,7 +67,6 @@
67#define PT_TRACE_EXEC 0x00000080 67#define PT_TRACE_EXEC 0x00000080
68#define PT_TRACE_VFORK_DONE 0x00000100 68#define PT_TRACE_VFORK_DONE 0x00000100
69#define PT_TRACE_EXIT 0x00000200 69#define PT_TRACE_EXIT 0x00000200
70#define PT_ATTACHED 0x00000400 /* parent != real_parent */
71 70
72#define PT_TRACE_MASK 0x000003f4 71#define PT_TRACE_MASK 0x000003f4
73 72
diff --git a/kernel/exit.c b/kernel/exit.c
index eb9934a82fc1..1f2c15297f2d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1514,18 +1514,7 @@ static int wait_task_continued(struct task_struct *p, int noreap,
1514 1514
1515static inline int my_ptrace_child(struct task_struct *p) 1515static inline int my_ptrace_child(struct task_struct *p)
1516{ 1516{
1517 if (!(p->ptrace & PT_PTRACED)) 1517 return p->ptrace & PT_PTRACED;
1518 return 0;
1519 if (!(p->ptrace & PT_ATTACHED))
1520 return 1;
1521 /*
1522 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1523 * we are the attacher. If we are the real parent, this is a race
1524 * inside ptrace_attach. It is waiting for the tasklist_lock,
1525 * which we have to switch the parent links, but has already set
1526 * the flags in p->ptrace.
1527 */
1528 return (p->parent != p->real_parent);
1529} 1518}
1530 1519
1531static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 1520static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 628b03ab88a5..2dc00298e678 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -100,8 +100,7 @@ int ptrace_check_attach(struct task_struct *child, int kill)
100 */ 100 */
101 read_lock(&tasklist_lock); 101 read_lock(&tasklist_lock);
102 if ((child->ptrace & PT_PTRACED) && child->parent == current && 102 if ((child->ptrace & PT_PTRACED) && child->parent == current &&
103 (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) 103 child->signal != NULL) {
104 && child->signal != NULL) {
105 ret = 0; 104 ret = 0;
106 spin_lock_irq(&child->sighand->siglock); 105 spin_lock_irq(&child->sighand->siglock);
107 if (task_is_stopped(child)) 106 if (task_is_stopped(child))
@@ -200,8 +199,7 @@ repeat:
200 goto bad; 199 goto bad;
201 200
202 /* Go */ 201 /* Go */
203 task->ptrace |= PT_PTRACED | ((task->real_parent != current) 202 task->ptrace |= PT_PTRACED;
204 ? PT_ATTACHED : 0);
205 if (capable(CAP_SYS_PTRACE)) 203 if (capable(CAP_SYS_PTRACE))
206 task->ptrace |= PT_PTRACE_CAP; 204 task->ptrace |= PT_PTRACE_CAP;
207 205
diff --git a/kernel/signal.c b/kernel/signal.c
index 5d30ff561847..6d6d1ab39e7e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1556,11 +1556,6 @@ static inline int may_ptrace_stop(void)
1556{ 1556{
1557 if (!likely(current->ptrace & PT_PTRACED)) 1557 if (!likely(current->ptrace & PT_PTRACED))
1558 return 0; 1558 return 0;
1559
1560 if (unlikely(current->parent == current->real_parent &&
1561 (current->ptrace & PT_ATTACHED)))
1562 return 0;
1563
1564 /* 1559 /*
1565 * Are we in the middle of do_coredump? 1560 * Are we in the middle of do_coredump?
1566 * If so and our tracer is also part of the coredump stopping 1561 * If so and our tracer is also part of the coredump stopping