linux-kernel - Re: [TIP] BUG kmalloc-4096: Poison overwritten (ath5k_rx_skb

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Message-ID: <20090224135817.GB6019@hash.localnet>
Date:	Tue, 24 Feb 2009 08:58:17 -0500
From:	Bob Copeland <me@...copeland.com>
To:	Nick Kossifidis <mickflemm@...il.com>
Cc:	Jiri Slaby <jirislaby@...il.com>,
	Sitsofe Wheeler <sitsofe@...oo.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
	ath5k-devel@...ema.h4ckr.net,
	"Luis R. Rodriguez" <lrodriguez@...eros.com>
Subject: Re: [TIP] BUG kmalloc-4096: Poison overwritten (ath5k_rx_skb_alloc)

On Tue, Feb 24, 2009 at 01:08:03AM +0200, Nick Kossifidis wrote:
> He does an extra check...
> 
> 	/*
> 	 * Given the use of a self-linked tail be very sure that the hw is
> 	 * done with this descriptor; the hw may have done this descriptor
> 	 * once and picked it up again...make sure the hw has moved on.
> 	 */
> 	if ((ands->ds_rxstatus1&AR_Done) == 0 && OS_REG_READ(ah, AR_RXDP) == pa)
> 		return HAL_EINPROGRESS;

Sounds like we definitely need that.  If the hw uses up all the dma buffers
in one go, there's a good chance we can send the skb to mac80211 while
the hardware is still using it.  I guess an easy way to test would be to
set the max rx buffers to 3 or so and watch the fireworks.

-- 
Bob Copeland %% www.bobcopeland.com

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