diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2009-04-02 16:58:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-02 19:04:59 -0700 |
| commit | 6d69cb87f05eef3b02370b2f7bae608ad2301a00 (patch) | |
| tree | 69f38afc49df51a1a75fc5c7792ced6888af329d | |
| parent | 95c3eb76dc07fd81289888ffc42948196b34b444 (diff) | |
| download | linux-6d69cb87f05eef3b02370b2f7bae608ad2301a00.tar.bz2 | |
ptrace: simplify ptrace_exit()->ignoring_children() path
ignoring_children() takes parent->sighand->siglock and checks
k_sigaction[SIGCHLD] atomically. But this buys nothing, we can't get the
"really" wrong result even if we race with sigaction(SIGCHLD). If we read
the "stale" sa_handler/sa_flags we can pretend it was changed right after
the check.
Remove spin_lock(->siglock), and kill "int ign" which caches the result of
ignoring_children() which becomes rather trivial.
Perhaps it makes sense to export this helper, do_notify_parent() can use
it too.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/exit.c | 25 |
1 files changed, 8 insertions, 17 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 0c06b9efae3b..7a8311422930 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -732,19 +732,15 @@ static void exit_mm(struct task_struct * tsk) } /* - * Return nonzero if @parent's children should reap themselves. - * - * Called with write_lock_irq(&tasklist_lock) held. + * Called with irqs disabled, returns true if childs should reap themselves. */ -static int ignoring_children(struct task_struct *parent) +static int ignoring_children(struct sighand_struct *sigh) { int ret; - struct sighand_struct *psig = parent->sighand; - unsigned long flags; - spin_lock_irqsave(&psig->siglock, flags); - ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || - (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT)); - spin_unlock_irqrestore(&psig->siglock, flags); + spin_lock(&sigh->siglock); + ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) || + (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT); + spin_unlock(&sigh->siglock); return ret; } @@ -757,7 +753,6 @@ static int ignoring_children(struct task_struct *parent) static void ptrace_exit(struct task_struct *parent, struct list_head *dead) { struct task_struct *p, *n; - int ign = -1; list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) { __ptrace_unlink(p); @@ -779,12 +774,8 @@ static void ptrace_exit(struct task_struct *parent, struct list_head *dead) if (!task_detached(p) && thread_group_empty(p)) { if (!same_thread_group(p->real_parent, parent)) do_notify_parent(p, p->exit_signal); - else { - if (ign < 0) - ign = ignoring_children(parent); - if (ign) - p->exit_signal = -1; - } + else if (ignoring_children(parent->sighand)) + p->exit_signal = -1; } if (task_detached(p)) { |