linux-kernel - Re: [GIT PULL] PM updates for 2.6.33

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: <Pine.LNX.4.44L0.0912061700420.9883-100000@netrider.rowland.org>
Date:	Sun, 6 Dec 2009 17:04:47 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Arjan van de Ven <arjan@...radead.org>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [GIT PULL] PM updates for 2.6.33

On Sun, 6 Dec 2009, Arjan van de Ven wrote:

> having spent 30 minutes trying to grok this code, I think there may be
> a trick in using the async function call infrastructure.
> 
> if each USB hub's resume (hub_resume()) would be done as an async
> function call, that would start allowing the hub resumes to go async,
> but this is not enough.
> 
> usb_resume_both() would also then need to be an async call itself, and
> do its "resume the parent" recursion as a async function call, and then
> it needs to do a synchronization before actually resuming the device
> itself (provided it is not a hub or hub like device I suppose).
> 
> the later synchronization guarantees that no device will be resumed
> before it's parent tree structure is resumed, while allowing parallel
> parts of the tree to be resumed in parallel.
> 
> The hard part in this is the locking.... that is getting non-trivial
> once you have multiple asynchronous functions executing.

That's the whole point of Rafael's async suspend/resume framework.  He 
has done the hard work already.

Alan Stern

--
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/