linux-kernel - Re: [PATCH 0 of 4] Generic AIO by scheduling stacks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 4 Feb 2007 12:00:04 -0800 (PST)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Zach Brown <zach.brown@...cle.com>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-aio@...ck.org, Suparna Bhattacharya <suparna@...ibm.com>,
	Benjamin LaHaise <bcrl@...ck.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 0 of 4] Generic AIO by scheduling stacks

On Sat, 3 Feb 2007, Davide Libenzi wrote:

> > - Signals.  I have no idea what behaviour we want.  Help?  My first guess is
> > that we'll want signal state to be shared by fibrils by keeping it in the
> > task_struct.  If we want something like individual cancellation,  we'll augment
> > signal_pending() with some some per-fibril test which will cause it to return
> > from TASK_INTERRUPTIBLE (the only reasonable way to implement generic
> > cancellation, I'll argue) as it would have if a signal was pending.
> 
> Fibril should IMO use current thread signal policies. I think a signal 
> should hit (wake) any TASK_INTERRUPTIBLE fibril, if the current thread 
> policies mandate that. I'd keep a list_head of currently scheduled-out 
> TASK_INTERRUPTIBLE fibrils, and I'd make them runnable when a signal is 
> delivered to the thread (wake_target bit #1 set to mean wake-all-interruptable-fibrils?).
> The other thing is signal_pending(). The sigpending flag test is not going 
> to work as is (cleared at the first do_signal). Setting a bit in each 
> fibril would mean walking the whole TASK_INTERRUPTIBLE fibril list. Maybe 
> a sequential signal counter in task_struct, matched by one in the fibril. 
> A signal would increment the task_struct counter, and a fibril 
> schedule-out would save the task_struct counter to the fibril. The 
> signal_pending() for a fibril is a compare of the two. Or something 
> similar.

Another thing linked to signals that was not talked about, is cancellation 
of an in-flight request. We want to give the ability to cancel an 
in-flight request, with something like async_cancel(cookie). In my 
userspace library I simply disable SA_RESTART of SIGUSR2, and I do a 
pthread_kill() on the thread servicing the request. But this will IMO have 
other implications (linked to signal delivery) in a kernel fibril-based 
implementation, to think about it.



- Davide


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/