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authorOleg Nesterov <oleg@redhat.com>2014-12-10 15:45:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 17:41:10 -0800
commit7c8bd2322c7fd973d089b27de55e29c92c667a06 (patch)
tree8d9c9d6dbc32eabc303368d913dab3c683b94e2d /kernel
parent2831096e21503897ee474c23131c3feb8db0ffb1 (diff)
exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()
Now that forget_original_parent() uses ->ptrace_entry for EXIT_DEAD tasks, we can simply pass "dead_children" list to exit_ptrace() and remove another release_task() loop. Plus this way we do not need to drop and reacquire tasklist_lock. Also shift the list_empty(ptraced) check, if we want this optimization it makes sense to eliminate the function call altogether. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/exit.c10
-rw-r--r--kernel/ptrace.c23
2 files changed, 7 insertions, 26 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 772e9175735c..9c9526d87276 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -553,13 +553,11 @@ static void forget_original_parent(struct task_struct *father)
LIST_HEAD(dead_children);
write_lock_irq(&tasklist_lock);
- /*
- * Note that exit_ptrace() and find_new_reaper() might
- * drop tasklist_lock and reacquire it.
- */
- exit_ptrace(father);
- reaper = find_new_reaper(father);
+ if (unlikely(!list_empty(&father->ptraced)))
+ exit_ptrace(father, &dead_children);
+ /* Can drop and reacquire tasklist_lock */
+ reaper = find_new_reaper(father);
list_for_each_entry(p, &father->children, sibling) {
for_each_thread(p, t) {
t->real_parent = reaper;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 54e75226c2c4..1eb9d90c3af9 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -485,36 +485,19 @@ static int ptrace_detach(struct task_struct *child, unsigned int data)
/*
* Detach all tasks we were using ptrace on. Called with tasklist held
- * for writing, and returns with it held too. But note it can release
- * and reacquire the lock.
+ * for writing.
*/
-void exit_ptrace(struct task_struct *tracer)
- __releases(&tasklist_lock)
- __acquires(&tasklist_lock)
+void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
{
struct task_struct *p, *n;
- LIST_HEAD(ptrace_dead);
-
- if (likely(list_empty(&tracer->ptraced)))
- return;
list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
if (unlikely(p->ptrace & PT_EXITKILL))
send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
if (__ptrace_detach(tracer, p))
- list_add(&p->ptrace_entry, &ptrace_dead);
- }
-
- write_unlock_irq(&tasklist_lock);
- BUG_ON(!list_empty(&tracer->ptraced));
-
- list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
- list_del_init(&p->ptrace_entry);
- release_task(p);
+ list_add(&p->ptrace_entry, dead);
}
-
- write_lock_irq(&tasklist_lock);
}
int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)