linux-kernel - Re: [take23 3/5] kevent: poll/select() notifications.

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Wed, 8 Nov 2006 20:03:59 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Davide Libenzi <davidel@...ilserver.org>
Cc:	David Miller <davem@...emloft.net>,
	Ulrich Drepper <drepper@...hat.com>,
	Andrew Morton <akpm@...l.org>, netdev <netdev@...r.kernel.org>,
	Zach Brown <zach.brown@...cle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Chase Venters <chase.venters@...entec.com>,
	Johann Borck <johann.borck@...sedata.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeff Garzik <jeff@...zik.org>
Subject: Re: [take23 3/5] kevent: poll/select() notifications.

On Wed, Nov 08, 2006 at 11:45:54AM +0300, Evgeniy Polyakov (johnpol@....mipt.ru) wrote:
> > Are you sure you can safely call file->f_op->poll() from inside a callback 
> > based wakeup? The low level driver may be calling the wakeup with one of 
> > its locks held, and during the file->f_op->poll may be trying to acquire 
> > the same lock. I remember there was a discussion about this, and assuming 
> > the above not true, made epoll code more complex (and slower, since an 
> > extra O(R) loop was needed to fetch events).
> 
> Indeed, I have not paid too much attention to poll/select notifications in 
> kevent actually. As far as I recall it should be called on behalf of process 
> doing kevent_get_event(). I will check and fix if that is not correct.
> Thanks Davide.

Indeed there was a bug.
Actually poll/select patch was broken quite noticebly - patchset did not
include major changes I made for it.
I will put them all into next release.

Thanks again Davide for pointing that out.

-- 
	Evgeniy Polyakov
-
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/