Messages in this thread |  | | | Date | Fri, 22 Apr 2011 13:46:16 +0100 | | From | Matt Fleming <> | | Subject | Re: [PATCH v2 5/7] signal: sigprocmask() should do retarget_shared_pending() |
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On Mon, 18 Apr 2011 15:45:57 +0200 Oleg Nesterov <oleg@redhat.com> wrote:
> In short, almost every changing of current->blocked is wrong, or at least > can lead to the unexpected results. > > For example. Two threads T1 and T2, T1 sleeps in sigtimedwait/pause/etc. > kill(tgid, SIG) can pick T2 for TIF_SIGPENDING. If T2 calls sigprocmask() > and blocks SIG before it notices the pending signal, nobody else can handle > this pending shared signal. > > I am not sure this is bug, but at least this looks strange imho. T1 should > not sleep forever, there is a signal which should wake it up. > > This patch moves the code which actually changes ->blocked into the new > helper, set_current_blocked() and changes this code to call > retarget_shared_pending() as exit_signals() does. We should only care about > the signals we just blocked, we use "newset & ~current->blocked" as a mask. > > We do not check !sigisemptyset(newblocked), retarget_shared_pending() is > cheap unless mask & shared_pending. > > Note: for this particular case we could simply change sigprocmask() to > return -EINTR if signal_pending(), but then we should change other callers > and, more importantly, if we need this fix then set_current_blocked() will > have more callers and some of them can't restart. See the next patch as a > random example. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
This looks much simpler to me.
Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com>
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