Hello Oleg Nesterov,
The patch eb6d8479b73d: "exit: reparent: cleanup the changing of
->parent" from Nov 13, 2014, leads to the following static checker
warning:
kernel/exit.c:543 forget_original_parent()
warn: add some parenthesis here?
kernel/exit.c
538 /* Can drop and reacquire tasklist_lock */
539 reaper = find_new_reaper(father);
540 list_for_each_entry(p, &father->children, sibling) {
541 for_each_thread(p, t) {
542 t->real_parent = reaper;
543 BUG_ON(!t->ptrace != (t->parent == father));
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The reason for this warning is that many people forget that ! is higher
precedence than ==. This is a complicated condition however you write
it, but it might be more clear to say:
BUG_ON((!!t->ptrace) == (t->parent == father));
I'm not sure.
544 if (likely(!t->ptrace))
545 t->parent = t->real_parent;
546 if (t->pdeath_signal)
547 group_send_sig_info(t->pdeath_signal,
548 SEND_SIG_NOINFO, t);
549 }
550 /*
551 * If this is a threaded reparent there is no need to
552 * notify anyone anything has happened.
553 */
554 if (!same_thread_group(reaper, father))
555 reparent_leader(father, p, &dead_children);
556 }
regards,
dan carpenter
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