Messages in this thread Patch in this message | | | Date | Sun, 6 Jul 2008 20:02:52 +0400 | From | Oleg Nesterov <> | Subject | [PATCH] ptrace: simplify ptrace_stop()->sigkill_pending() path |
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1. SIGKILL can't be blocked, remove this check from sigkill_pending().
2. When ptrace_stop() sees sigkill_pending() == T, it can just return. Kill "int killed" and simplify the code. This also is more correct, the tracer shouldn't see us in TASK_TRACED if we are not going to stop.
I strongly believe this code needs further changes. We should do the "was this task killed" check unconditionally, currently it depends on arch_ptrace_stop_needed(). On the other hand, sigkill_pending() isn't very clever. If the task was killed tkill(SIGKILL), the signal can be already dequeued if the caller is do_exit().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 26-rc2/kernel/signal.c~PT_KILL 2008-06-28 17:06:58.000000000 +0400 +++ 26-rc2/kernel/signal.c 2008-07-06 19:29:27.000000000 +0400 @@ -1498,9 +1498,8 @@ static inline int may_ptrace_stop(void) */ static int sigkill_pending(struct task_struct *tsk) { - return ((sigismember(&tsk->pending.signal, SIGKILL) || - sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) && - !unlikely(sigismember(&tsk->blocked, SIGKILL))); + return sigismember(&tsk->pending.signal, SIGKILL) || + sigismember(&tsk->signal->shared_pending.signal, SIGKILL); } /* @@ -1516,8 +1515,6 @@ static int sigkill_pending(struct task_s */ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) { - int killed = 0; - if (arch_ptrace_stop_needed(exit_code, info)) { /* * The arch code has something special to do before a @@ -1533,7 +1530,8 @@ static void ptrace_stop(int exit_code, i spin_unlock_irq(¤t->sighand->siglock); arch_ptrace_stop(exit_code, info); spin_lock_irq(¤t->sighand->siglock); - killed = sigkill_pending(current); + if (sigkill_pending(current)) + return; } /* @@ -1550,7 +1548,7 @@ static void ptrace_stop(int exit_code, i __set_current_state(TASK_TRACED); spin_unlock_irq(¤t->sighand->siglock); read_lock(&tasklist_lock); - if (!unlikely(killed) && may_ptrace_stop()) { + if (may_ptrace_stop()) { do_notify_parent_cldstop(current, CLD_TRAPPED); read_unlock(&tasklist_lock); schedule();
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