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

Will Deacon will.deacon at arm.com
Tue Jan 25 08:57:26 EST 2011

Hi Russell,

Hopefully this isn't too late to be useful.

> On Mon, Jan 17, 2011 at 07:21:40PM +0000, Russell King - ARM Linux wrote:
> > 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 <rmk+kernel at arm.linux.org.uk>
> 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 <will.deacon at arm.com>

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


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