From: Oliver Neukum <oliver@neukum.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Christian Eggers" <ceggers@gmx.de>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH] usb/mcs7830: Don't use buffers from stack for USB transfers
Date: Tue, 20 Jan 2009 23:50:21 +0100 [thread overview]
Message-ID: <200901202350.23231.oliver@neukum.org> (raw)
In-Reply-To: <200901202345.47792.arnd@arndb.de>
Am Tuesday 20 January 2009 23:45:47 schrieb Arnd Bergmann:
> Have you observed problems with this, or just suspected trouble?
>
> When I wrote this code, I looked at other code doing the same
> and assumed it was ok, because usb_control_msg waits for the
> DMA to complete before returning.
>
> Is the problem only on systems that have noncoherent DMA, or
> something else?
That's not enough. Tasks can leave pointers to variables on the
stack to other tasks. You must under no circumstances do DMA
on the stack if the driver may run on system that have noncoherent
DMA.
Regards
Oliver
prev parent reply other threads:[~2009-01-20 22:50 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-20 20:29 [PATCH] usb/mcs7830: Don't use buffers from stack for USB transfers Christian Eggers
2009-01-20 20:32 ` David Miller
2009-01-20 22:45 ` Arnd Bergmann
2009-01-20 22:47 ` David Miller
2009-01-20 23:17 ` Arnd Bergmann
2009-01-20 23:23 ` David Miller
2009-01-20 23:36 ` Oliver Neukum
2009-01-20 23:37 ` Arnd Bergmann
2009-01-20 23:39 ` David Miller
2009-01-20 23:28 ` Oliver Neukum
2009-01-20 22:50 ` Oliver Neukum [this message]
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