From 7c8bd2322c7fd973d089b27de55e29c92c667a06 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:45:33 -0800 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 Cc: Aaron Tomlin Cc: Alexey Dobriyan Cc: "Eric W. Biederman" , Cc: Sterling Alexander Cc: Peter Zijlstra Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/ptrace.c | 23 +++-------------------- 1 file changed, 3 insertions(+), 20 deletions(-) (limited to 'kernel/ptrace.c') 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) -- cgit