linux-kernel - Re: [Bug 10030] Suspend doesn't work when SD card is inserted

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]

Message-Id: <200802251241.26216.rjw@sisk.pl>
Date:	Mon, 25 Feb 2008 12:41:25 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Pavel Machek <pavel@....cz>, Pierre Ossman <drzeus-mmc@...eus.cx>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [Bug 10030] Suspend doesn't work when SD card is inserted

On Monday, 25 of February 2008, Alan Stern wrote:
> On Sun, 24 Feb 2008, Rafael J. Wysocki wrote:
> 
> > > Very subtly wrong ;-).
> > > 
> > > imagine suspending_task == 0xabcdef01. Now task "R" with current ==
> > > 0xabcd0000 reads suspending_task while the other cpu is writing to it,
> > > and sees 0xabcd0000 (0xef01 was not yet written) -- and mistakenly
> > > believes that  "R" == suspending_task.
> > > 
> > > I agree it is very unlikely, and it will not happen on i386. But what
> > > about just using atomic_t suspending_task, and store current->pid into
> > > it?
> > 
> > I'd rather use a lock, frankly.  For example, we can require the readers to
> > take pm_sleep_rwsem for reading in order to access that.
> 
> That certainly won't work.  Imagine what would happen when the reader 
> _was_ the suspending task.

Yeah, I've already realized it was a stupid idea. :-)

> But if you really twist my arm, I'll go along with Pavel's suggestion.

So can you do that, pretty please?

Thanks,
Rafael
--
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/