linux-kernel - Re: Bugs in MMC [was: [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: <Pine.LNX.4.44L0.0803041245460.15190-100000@iolanthe.rowland.org>
Date:	Tue, 4 Mar 2008 12:50:08 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	David Brownell <david-b@...bell.net>
cc:	Pierre Ossman <drzeus-mmc@...eus.cx>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD card
 is inserted]

On Mon, 3 Mar 2008, David Brownell wrote:

> Card insert/remove events can be system wake events though.  Which
> makes that restriction impractical.
> 
> I think hosts need to be able to call mmc_detect_change() as soon as
> they see a stable signal.  The MMC core can hold off handling that
> for a while, if it needs to wait until the code walking the device
> tree gets around to resuming that host.  It's a lot more natural to
> hold off such stuff one time there than in N host drivers; especially
> since the MMC core already has such hold-off code.

That's what ended up happening.  The workqueue used by
mmc_detect_change() was made freezable, so hosts could call the routine
at any time but it wouldn't do anything until the system sleep was
over.

A more flexible approach would avoid freezing the workqueue, and allow 
it to process card removals at any time.  But card insertions would be 
ignored if the mmc_host device was suspended; at resume time the core 
probes for changes that occurred during the sleep.

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/