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SubjectRe: [patch] ptrace-fix-2.5.33-A1

On Fri, 6 Sep 2002, Daniel Jacobowitz wrote:

> Because it's also needed for non-CLONE_DETACH processes. I added it
> earlier down by the release_task, remember? I deleted it in this patch
> originally, and the change got lost somewhere; my intent is to check for
> this only in release_task and nowhere else. When I have a clear point
> to resync with Linus again then I'll make sure this is right.

Linus' tree is at http://linux.bkbits.net/linux-2.5/, and i've done the
attached patch to collect & clean up all the things that happened since
yesterday. It's basically what was your tree this morning - i'd suggest
for you to base subsequent patches on BK-curr + this patch. (To reduce
confusion i wont send any new patches for this area from now on.)

Ingo

diff -rNu linux.orig/kernel/exit.c linux/kernel/exit.c
--- linux.orig/kernel/exit.c Fri Sep 6 11:37:53 2002
+++ linux/kernel/exit.c Fri Sep 6 11:39:47 2002
@@ -66,8 +66,12 @@
atomic_dec(&p->user->processes);
security_ops->task_free_security(p);
free_uid(p->user);
- BUG_ON(p->ptrace || !list_empty(&p->ptrace_list) ||
- !list_empty(&p->ptrace_children));
+ if (unlikely(p->ptrace)) {
+ write_lock_irq(&tasklist_lock);
+ __ptrace_unlink(p);
+ write_unlock_irq(&tasklist_lock);
+ }
+ BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
unhash_process(p);

release_thread(p);
@@ -428,7 +432,7 @@
* There are only two places where our children can be:
*
* - in our child list
- * - in the global ptrace list
+ * - in our ptraced child list
*
* Search them and reparent children.
*/
@@ -443,14 +447,22 @@
read_unlock(&tasklist_lock);
}

-static inline void zap_thread(task_t *p, task_t *father)
+static inline void zap_thread(task_t *p, task_t *father, int traced)
{
- ptrace_unlink(p);
- list_del_init(&p->sibling);
- p->ptrace = 0;
+ /* If we were tracing the thread, release it; otherwise preserve the
+ ptrace links. */
+ if (unlikely(traced)) {
+ task_t *trace_task = p->parent;
+ __ptrace_unlink(p);
+ p->ptrace = 1;
+ __ptrace_link(p, trace_task);
+ } else {
+ p->ptrace = 0;
+ list_del_init(&p->sibling);
+ p->parent = p->real_parent;
+ list_add_tail(&p->sibling, &p->parent->children);
+ }

- p->parent = p->real_parent;
- list_add_tail(&p->sibling, &p->parent->children);
if (p->state == TASK_ZOMBIE && p->exit_signal != -1)
do_notify_parent(p, p->exit_signal);
/*
@@ -541,11 +553,11 @@

zap_again:
list_for_each_safe(_p, _n, &current->children)
- zap_thread(list_entry(_p,struct task_struct,sibling), current);
+ zap_thread(list_entry(_p,struct task_struct,sibling), current, 0);
list_for_each_safe(_p, _n, &current->ptrace_children)
- zap_thread(list_entry(_p,struct task_struct,ptrace_list), current);
+ zap_thread(list_entry(_p,struct task_struct,ptrace_list), current, 1);
/*
- * reparent_thread might drop the tasklist lock, thus we could
+ * zap_thread might drop the tasklist lock, thus we could
* have new children queued back from the ptrace list into the
* child list:
*/
@@ -716,17 +728,11 @@
retval = p->pid;
if (p->real_parent != p->parent) {
write_lock_irq(&tasklist_lock);
- ptrace_unlink(p);
+ __ptrace_unlink(p);
do_notify_parent(p, SIGCHLD);
write_unlock_irq(&tasklist_lock);
- } else {
- if (p->ptrace) {
- write_lock_irq(&tasklist_lock);
- ptrace_unlink(p);
- write_unlock_irq(&tasklist_lock);
- }
+ } else
release_task(p);
- }
goto end_wait4;
default:
continue;

-
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