Re: [PATCH v2] devres: Really align data field to unsigned long long

Greg KH
2018-07-08T18:41:00Z

On Sun, Jul 08, 2018 at 08:56:21PM +0300, Alexey Brodkin wrote:
> Depending on ABI "long long" type of a particular 32-bit CPU
> might be aligned by either word (32-bits) or double word (64-bits).
> Make sure "data" is really 64-bit aligned for any 32-bit CPU.
>
> At least for 32-bit ARC cores ABI requires "long long" types
> to be aligned by normal 32-bit word. This makes "data" field aligned to
> 12 bytes. Which is still OK as long as we use 32-bit data only.
>
> But once we want to use native atomic64_t type (i.e. when we use special
> instructions LLOCKD/SCONDD for accessing 64-bit data) we easily hit
> misaligned access exception.
>
> That's because even on CPUs capable of non-aligned data access LL/SC
> instructions require strict alignment.
>
> Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: stable@vger.kernel.org
> ---
>
> Changes v1 -> v2:
>
> * Reworded commit message
> * Inserted comment right in source [Thomas]
>
> drivers/base/devres.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)

Always use scripts/get_maintainer.pl to properly cc: the needed
developer/maintainer. As it is, this patch is going to get dropped on
the floor, sorry...

greg k-h