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    SubjectRe: [PATCH 40/41] ncpfs: Use set_current_blocked()
    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(&current->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(&current->blocked, mask);
    > - recalc_sigpending();
    > +
    > + siginitsetinv(&blocked, mask);
    > + __set_task_blocked(current, &blocked);
    > spin_unlock_irqrestore(&current->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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