Messages in this thread | | | Date | Wed, 6 Jun 2007 15:36:30 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: signalfd API issues (was Re: [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes) |
| |
On Wed, 6 Jun 2007, Benjamin Herrenschmidt wrote:
> On Tue, 2007-06-05 at 20:37 -0700, Linus Torvalds wrote: > > > I agree that it would be a limitation, but it would be a sane one. > > > > How about we try to live with that limitation, if only to avoid the issue > > of having the private signals being stolen by anybody else. If we actually > > find a real-live use-case where that is bad in the future, we can re-visit > > the issue - it's always easier to _expand_ semantics later than it is to > > restrict them, so I think this thread is a good argument for starting it > > out in a more restricted form before people start depending on semantics > > that can be nasty.. > > Here's a patch. Let me know if I missed something. > > Fix races with signalfd and TIF_SIGPENDING > > We must never clear TIF_SIGPENDING for another task. This patch > ensures that by preventing recalc_sigpending_tsk() from clearing > that bit if the target task is not current. > > In addition we also prevent __dequeue_signal() from calling the > DRM notifier thingy when stealing signals from another task via > signalfd. > > Finally, we only dequeue shared signals when called from another > task (via signalfd), we leave private signals alone.
Makes sense...
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
- Davide
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |