The patch titled
Subject: exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()
has been added to the -mm tree. Its filename is
exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent.patch
echo and later at
echo http://ozlabs.org/~akpm/mmotm/broken-out/exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Cc: Aaron Tomlin <atomlin@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>,
Cc: Sterling Alexander <stalexan@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ptrace.h | 2 +-
kernel/exit.c | 10 ++++------
kernel/ptrace.c | 23 +++--------------------
3 files changed, 8 insertions(+), 27 deletions(-)
diff -puN include/linux/ptrace.h~exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent include/linux/ptrace.h
--- a/include/linux/ptrace.h~exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent
+++ a/include/linux/ptrace.h
@@ -52,7 +52,7 @@ extern void ptrace_notify(int exit_code)
extern void __ptrace_link(struct task_struct *child,
struct task_struct *new_parent);
extern void __ptrace_unlink(struct task_struct *child);
-extern void exit_ptrace(struct task_struct *tracer);
+extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
#define PTRACE_MODE_READ 0x01
#define PTRACE_MODE_ATTACH 0x02
#define PTRACE_MODE_NOAUDIT 0x04
diff -puN kernel/exit.c~exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent kernel/exit.c
--- a/kernel/exit.c~exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent
+++ a/kernel/exit.c
@@ -553,13 +553,11 @@ static void forget_original_parent(struc
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 -puN kernel/ptrace.c~exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent kernel/ptrace.c
--- a/kernel/ptrace.c~exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent
+++ a/kernel/ptrace.c
@@ -485,36 +485,19 @@ static int ptrace_detach(struct task_str
/*
* 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);
+ list_add(&p->ptrace_entry, 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);
- }
-
- write_lock_irq(&tasklist_lock);
}
int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
mmfs-introduce-helpers-around-the-i_mmap_mutex.patch
mm-use-new-helper-functions-around-the-i_mmap_mutex.patch
mm-convert-i_mmap_mutex-to-rwsem.patch
mm-rmap-share-the-i_mmap_rwsem.patch
uprobes-share-the-i_mmap_rwsem.patch
mm-xip-share-the-i_mmap_rwsem.patch
mm-memory-failure-share-the-i_mmap_rwsem.patch
mm-nommu-share-the-i_mmap_rwsem.patch
mm-memoryc-share-the-i_mmap_rwsem.patch
proc-task_state-read-cred-group_info-outside-of-task_lock.patch
proc-task_state-deuglify-the-max_fds-calculation.patch
proc-task_state-move-the-main-seq_printf-outside-of-rcu_read_lock.patch
proc-task_state-ptrace_parent-doesnt-need-pid_alive-check.patch
sched_show_task-fix-unsafe-usage-of-real_parent.patch
exit-reparent-use-ptrace_entry-rather-than-sibling-for-exit_dead-tasks.patch
exit-reparent-cleanup-the-changing-of-parent.patch
exit-reparent-cleanup-the-usage-of-reparent_leader.patch
exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent.patch
usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper.patch
usermodehelper-kill-the-kmod_thread_locker-logic.patch
linux-next.patch
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