[PATCH 02/14] ARM: bitops: switch set/clear/change bitops to use ldrex/strex

On Tue, 25 Jan 2011, Will Deacon wrote:

Hi Russell,

Hopefully this isn't too late to be useful.

quoted

On Mon, Jan 17, 2011 at 07:21:40PM +0000, Russell King - ARM Linux wrote:

quoted

Switch the set/clear/change bitops to use the word-based exclusive
operations, which are only present in a wider range of ARM architectures
than the byte-based exclusive operations.

Signed-off-by: Russell King <redacted>

As only one person replied to this patch with test information, I'm
not happy to push this into -rc, and hence that prevents it going into
-stable too.  That means omap2plus_defconfig .38 mainline kernels
(including -stable) will remain potentially dangerous when run on
SMP capable hardware.

Therefore, I see no alternative at the moment but to purposely cause
builds which cover ARMv6, and ARMv6K or ARMv7 CPUs to save people from
data corruption.

Please get your tested-by's to me for at least the first three patches
of this series ASAP.

I've tested this on the Versatile Express (ca9x4, little endian) with a USB
hard drive and ext3 (rw) filesystem. I did a bunch of parallel dds of a 2GB
file containing random data whilst the system was fairly loaded. File checksums
all passed and the kernel didn't do anything untowards.

Tested-by: Will Deacon <redacted>

I appreciate this is the same test configuration as the one Nicolas did,
but it at least replicates his findings.

Well, I did run parallel instances of the git test suite on a Dove board 
using the sata_mv driver.  Therefore this is still a significant
difference in configuration which is good.


Nicolas