Michael Chan 581daf7e00 bnx2: Fix panic in bnx2_poll_work(). ...

Add barrier() to bnx2_get_hw_{tx|rx}_cons() to fix this issue:

http://bugzilla.kernel.org/show_bug.cgi?id=12698

This issue was reported by multiple i386 users.  Without barrier(),
the compiled code looks like the following where %eax contains the
address of the tx_cons or rx_cons in the DMA status block.  The
status block contents can change between the cmpb and the movzwl
instruction.  The driver would crash if the value was not 0xff during
the cmpb instruction, but changed to 0xff during the movzwl
instruction.

6828:	80 38 ff             	cmpb   $0xff,(%eax)
682b:	0f b7 10             	movzwl (%eax),%edx

With the added barrier(), the compiled code now looks correct:

683d:	0f b7 10             	movzwl (%eax),%edx
6840:	0f b6 c2             	movzbl %dl,%eax
6843:	3d ff 00 00 00       	cmp    $0xff,%eax

Thanks to Pascal de Bruijn <pmjdebruijn@pcode.nl> for reporting the
problem and Holger Noefer <hnoefer@pironet-ndh.com> for patiently
testing test patches for us.

Also updated version to 2.0.1.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2009-05-06 16:46:47 -07:00

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