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

[Nicolas Pitre]

On Tue, 25 Jan 2011, Will Deacon wrote:

> 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.

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