| Date | Tue, 16 Aug 2011 19:56:43 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 40/41] ncpfs: Use set_current_blocked() |
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On 08/11, Matt Fleming wrote: > > As described in e6fa16ab ("signal: sigprocmask() should do > retarget_shared_pending()") the modification of current->blocked is > incorrect as we need to check whether the signal we're about to block > is pending in the shared queue.
I'd wish I could understand this code but this seems impossible ;) IOW, "This doesn't seem right at all." looks reasonable, and the PF_EXITING adds even more confusion.
As for this patch, it looks (almost) fine anyway. But,
> @@ -749,7 +749,7 @@ static int ncp_do_request(struct ncp_server *server, int size, > return -EIO; > } > { > - sigset_t old_set; > + sigset_t old_set, blocked; > unsigned long mask, flags; > > spin_lock_irqsave(¤t->sighand->siglock, flags); > @@ -769,16 +769,14 @@ static int ncp_do_request(struct ncp_server *server, int size, > if (current->sighand->action[SIGQUIT - 1].sa.sa_handler == SIG_DFL) > mask |= sigmask(SIGQUIT); > } > - siginitsetinv(¤t->blocked, mask); > - recalc_sigpending(); > + > + siginitsetinv(&blocked, mask); > + __set_task_blocked(current, &blocked); > spin_unlock_irqrestore(¤t->sighand->siglock, flags);
Why do we take ->siglock in the first place?
I think it is not needed. We can calculate mask/blocked lockless and use set_task_blocked(). This also makes sense because __set_task_blocked is not exported ;)
the sighand->action[] checks are racy anyway in the mt case, siglock can't help.
Oleg.
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