Re: [patch 2/5] signalfd v2 - signalfd core ...

[Davide Libenzi <davidel@xmailserver.org>]

On Fri, 9 Mar 2007, Oleg Nesterov wrote:

> > Logic is, if it's not an RT signal, queue only one, otherwise multiple.
> > The bit on the ->pending mask is clealer only when the queue slot becomes empty.
> 
> Yes, I see what the code does, but I don't undestand why. For example, SIGCHLD was
> delivered to the process _and_ handled several times, then sys_signalfd_dequeue()
> comes and finds only one siginfo. Isn't this strange?

That's the same logic the kernel folows for non-RT signals. 


> > The two trasports can rely on different masks. The signalfd_notify() does 
> > not even go in signalfd_deliver() if no signalfds are attached to the 
> > sighand.
> 
> Sorry, I don't understand. The masks are different, yes, but ->sighand is the
> same? How this can make any difference for "if no signalfds are attached" ?

The list_empty() che would not make you fall inside signalfd_deliver(), 
hence the fast path really lives up to its name ;)


> Also. A malicious user can eat all memory, signalfd_deliver()->kmem_cache_alloc()
> doesn't check any limits.

I'll make that use the std dequeu_signal, so everything is handled in there.



- Davide